Nursing a Viper #142

During our more than 50 years of gardening, various weeds have flourished on our property. Some, like oxalis (O. pes-caprae, O. corniculta, creeping spurge (Euphorbia maculata), and sow thistle (Sonchus oleraceus) we always have with us. Others, like purslane (Potulaca oleracea) and petty spurge (E. peplus) can sprout aggressively one year and almost disappear another. This year the pest du jour is wild carrot, which I don’t recall having been a problem before.

If you define a weed simply as a plant growing in the wrong place, in recent years our weeding has increasingly been directed towards plants we have introduced ourselves. Some, like the South African bulb, Anomatheca laxa, were gifts from friends during our time as novices in Southern California gardening. Some, like feverfew (Tanacetum parthenium) and the Corsican hellebore (H. argutifolius), we acquired during a phase of enthusiasm for the English cottage garden, but they have now turned feral, seedlings of the former reverting from a named double-flowered cultivar. We bought a violet flowered columbine, probably Aquilegia vulgaris, many years ago and it was well behaved until the last two years when seedlings appeared everywhere. If it’s allowed to get established it can develop deep roots that make digging it out a chore.

Left to right:  Verbena bonariensis,  Linaria maroccana and Moraea polystachia

Verbena bonariensis has some admirable qualities, which is why we haven’t attempted to eradicate it since we bought a plant some 40 years ago. It is drought tolerant, blooms for much of the year, and the birds, especially lesser goldfinch, love it. However, our compost is loaded with the seeds. The seedlings are easily removed, so long as you recognize them early.

We were given some seedlings of Moroccan toadflax (Linaria maroccana) a half dozen years ago, and it has reseeded itself mightily since then. It comes in a variety of colours, and unlike Nemesia whose behaviour is similar, its progeny don’t revert to a bland monochrome. The photo shows the magnificent display it puts on at the height of its blooming season in late March and early April. When the blooms fade a major cleanup is needed. If you want to protect less aggressive plantings from being overwhelmed, you need to attack the myriad seedlings with a scuffle hoe when they first emerge in February. How about using a pre-emergence weed killer? I’m insulted that you think I would even consider such an abomination.

Moraea polystachia was one of my early purchases from Richard Doutt when I first became interested in rare South African bulbs, some 35 years ago. I have lost most of my collection over the years, victims of rodent attack or some inadvertently dug up or tossed out during their long dormant season. M. polystachia, unlike the more desirable members of the genus, begins growing and blooming in September, and continues to bloom until spring, producing numerous seed pods all the while. It seems especially aggressive in La Jolla, and some bulb fanciers from farther north envy my ability to propagate it. I’ve been tempted to eradicate it, but the blooms are so attractive that I can’t bring myself to exhibit the glyphosate. The photo shows why that might become necessary.

Brussels Sprouts #141

I’ve been writing this column for nearly a quarter century but have never produced an article on this estimable vegetable. We’ve made a few attempts to grow them, usually the widely available variety, ‘Jade Cross’, but have never had a satisfactory result. The problem is that the sprouts won’t head up, apparently lacking the necessary cool nights. Last year I read about the variety, ‘Marte’, in an article claiming that it would produce good sprouts in warm winter areas where the standard varieties are unsuccessful. Given the warming climate that has transformed some of our summer vegetables to perennials, I was sceptical about what ‘Marte’ could accomplish in the opposite direction, but I gave it a try this year.

Both in this country and in the UK, Brussels sprouts top the league table of ‘most hated vegetables’. They owe this reputation to the bitterness, shared to a degree by all Brassica vegetables, conferred by sulphur-containing compounds called glucosinolates. When the sprouts are cooked, chopped or chewed, these break down into the bitter isothiacinates (ITC). One of the ITCs, phenylthiocarbamide, is not found in sprouts but it is the substance used to test whether you carry the gene that allows you to detect the bitterness of ITCs. You may remember from your high school biology course that about a third of the class tasted nothing when presented with filter paper soaked with the compound. Not all tasters are Brassica haters but non-tasters are more likely to report that they enjoy sprouts.

Some thirty years ago, breeders in the Netherlands began selecting cultivars of sprouts that produced lesser amounts of glucosinolates and now there are several non-bitter varieties, including ‘Igor’, ‘Gustus’ and some purple types. Most of the sprouts sold in the supermarket are now harvested from less pungent varieties, and this may explain why some of you now enjoy them, though you hated them as children. Bitterness can also be reduced by cooking the sprouts soon after harvest and avoiding overcooking.

I couldn’t find much about the history of ‘Marte,' but it did receive an RHS award of garden merit. Some sellers describe it as free of bitterness while others describe it as having a “strong traditional taste”, seemingly dissonant claims.

I started seeds on the last day of August and set out three plants four weeks later. They flourished through the autumn and the beginnings of sprouts appeared at the axils early in December. For a while it looked as though they would not form compact heads but, to my surprise and delight, I was able to harvest a bunch of beautiful sprouts two days after Christmas. I had never eaten sprouts straight from the garden and these were better than anything I had experienced before. For the last month Helen has served them two or three times a week and it looks as though they will remain productive for another couple of weeks. This year I’ll plan on starting the seeds a week earlier and making a second planting at the end of September.

Soil Science for Gardeners #140

Recently I read a book with the above title by Robert Pavlis, a well-known speaker and writer on gardening topics who owns a six-acre botanical garden in Guelph, Ontario. The book debunks several myths that I admit having accepted over the years and has changed some of my ideas, especially relative to fertilizing. The advice one gets from magazines and web magazines is very helpful on managing seeds, seedlings and plants with respect to water, light, diseases and pests, but has little to say about soil care, apart from recommendations to add organic material and fertilizer. The author’s background is in chemistry and as a chemist he explains things that are confusingly vague in most garden writing. The book is well worth reading completely, but here to whet your appetite I’ll share a couple of his insights that were thought-provoking for me.

For many years I have used “balanced fertilizer” containing ‘equal amounts’ of nitrogen, phosphorus and potassium (K). The amounts are not truly equal because the phosphorus content is actually the amount of phosphoric acid (P2O5) and the potassium is in the form of potash (K2O) , so the true N-P-K proportions in a 10-10-10 mix are 10 - 4.36- 8.3. I generally looked for the highest absolute amounts of each, like 15-15-15, mainly because that gives you the biggest bang for your buck, Of course, plants don’t use equal amount of each nutrient, but there is some comfort in believing that you’ve supplied an adequate amount of each.

Ai first glance, the fact that the fertilizers are not truly balanced would seem a mere semantic issue. A much more important problem is that the persistence of each component in your soil is quite different. The nitrogen compounds in most commercial fertilizers are rapidly soluble in water and so are quickly available to your growing plants. However, this solubility also means that they will rapidly be leached out of the vicinity of the roots with watering or rainfall and so must be applied more frequently to be effective.

It's more difficult to know whether potassium needs to be added to an established garden and, if so, how much. Potassium is an essential nutrient, and in its available form as the soluble ion it is readily leached from the soil. However, most soil contains slowly available insoluble forms and San Diego municipal water contains more than most tap water. There is certainly much more than needed in your ‘balanced’ fertilizer.

“Phosphorus is a critical part of plant growth”, being a component of DNA and RNA as well as ATP (adenosine triphosphate), “the substance of life”. Agricultural soils that have been harvested for many years may be deficient in phosphorus and the same may be so for gardens on land recently converted from farms to housing. These may need added phosphorus for a few years but little will be needed thereafter. “Stable phosphorus” is held strongly by the soil and can build up to toxic levels with repeated application. Pavlis summarizes, “The bottom line for home gardeners is simple: Too much phosphorus is bad for the environment and may harm soil organisms. Unless your soil test indicates a shortage of phosphorus, you should assume that your soil has plenty of it and don’t add more in the form of commercial fertilizers.”

Yipes, this is pretty alarming. I’ve been adding phosphorus with each new planting, sometimes three times a year, to my vegetable beds which are now 38 years old. The new plantings are flourishing and so I don’t seem to have done any damage so far, but I plan to be very sparing with everything but nitrogen in the future.

Well, maybe I should have the soil tested, but where should I select the samples? I have 20 vegetable beds, some like the asparagus and blackberry beds with permanent plantings. Some, shaded during the winter by the neighbour’s tall hedge to the south, are used only half of the year and are planted only once per season. Some get year-round full sun and may be freshly planted and fertilized up to four times a year.  Pavlis discusses soil testing in much greater detail than I can go into here but summarizes, “A soil test can give you some quick insights into a new garden, but if you have been gardening in a place for a while or moved into a home with established gardens where things are growing well, you probably don’t need a soil test.”

So, that might leave you with the question, do I need to fertilize at all? Pavlis’ answer is that you don’t need to fertilize if you mulch with an organic material or add compost yearly, if you return plant material to the garden instead of sending it to the landfill, and if your plants are growing well. If they aren’t doing well, lack of nutrients is rarely the problem. 

This probably doesn’t apply to a bed where you’re making repeated plantings of rapidly growing vegetables and are using the whole plant at the table or putting the inedible parts on the compost pile. The same may be true of roses if you’re pruning them properly, removing much of the new growth after each blooming cycle, and perhaps three quarters of the whole plant at the winter pruning. In the vegetable beds I plan to continue my current practice of adding compost every time I plant seeds or set out new seedlings. I will occasionally add a high nitrogen fertilizer to crops like corn and cold vegetables but will supply nothing but compost to legumes and root vegetables.

Broccoli as a "Perennial" #139

As our winters have warmed, the summer vegetables have produced later in the season, while tomatoes and eggplants have survived and have supplied a useful harvest through the winter months. They eventually die but we have plants still producing that were started from seed more than a year ago. Broccoli has also proven itself a plant of unexpected longevity, but this has nothing to do with the climate. We’ve simply learned that with the right kind of pruning, even senescent plants can be kept productive.   

We discovered this phenomenon a couple of years ago when the rabbits, which normally ignore our vegetables, seemingly preferring the lawn, began aggressively attacking some of our edibles. We were fairly successful in protecting our seedlings by surrounding them with insect barrier netting, as I described in a previous article (Dec 2020), but I left in the ground some old broccoli plants that I normally would have pulled, hoping they would divert the bunnies from our more desirable plantings. They certainly did snack regularly on the broccoli, though it’s hard to say whether this ‘appeasement policy’ was any more successful than Chamberlain’s. What we did see was that the new growths sprouting from the base and from the roots of the old plants were kept nicely trimmed, while the larger stems at the centre were unmolested.

Ordinarily we pull up the plants when they begin to put up a multitude of side shoots with florets too small to be worth harvesting. This year we found the old plant occasionally forming florets up to a couple of inches in diameter and a greater number that were smaller but still of a size worth cutting. The four plants that we left in place produced enough for an occasional meal. During the warmest days of what was an unusually cool summer the individual buds were a bit thin and dry but fresh cut they were of acceptable quality. As the weather cooled in late September, the buds became plumper, and we found ourselves enjoying broccoli two or three times a week with some to give away. As I write in the last week of November the new plants, started from seed in late August, are still a week or so short of being ready for harvest. I probably won’t consider digging up the old plants at least until the new year, especially because this year’s second planting was hit by rabbits when I forgot to replace the hot caps after fertilizing them.

As I explained in a previous article, you need to prune the old plants aggressively if you want them to continue producing florets of a size worth harvesting. All spindly new growth from the roots or the trunks of the old plants must be ripped out. When you do cut a floret, the growth bearing it should be cut back to a stem at least an inch in diameter. After you’ve done this for a while you’ll get a feel for which new shoots are likely to mature to a good head and which should be sacrificed before they split into many tiny florets.

Revisiting the Pole bean ‘Fortex’ #138

I’ve been writing this column for nearly a quarter century, and I’ve long exhausted new topics for discussion. Therefore, it is with no apology that I frequently return to old favourites that have performed wonderfully for me over the years. Snap, or French, beans are a prime example. Those sold at the supermarket are mediocre on a good day and so, to enjoy them at their best, you must grow your own. They are easy to grow, very productive and friends are always glad to take them when you have a surplus. We’ve grown many varieties of snap bean over the years but have settled on ‘Fortex’, which is unmatched for flavour. The pods are longer than those of most French beans and can be harvested at 8 to 11 inches with no development of stringiness or toughness. When cooked to the right point they have a pleasant and characteristic mouth feel that I’ve found in no other variety of bean.

The one serious fault of this variety is that it’s very subject to damping off and you may lose from a quarter to as many as two thirds of the sprouted seedlings, mostly when the plants are a few inches tall but further losses will occur, even when they reach harvesting size. This means that you want to start a lot of seeds per planting, like 40 to 50. This gets expensive if you’re buying seed from the catalogues. It’s not a problem for us because they are open-pollinated and we’ve been replanting saved seed for some 20 years, with no apparent deterioration in the quality or quantity.

 I’ve experimented with many methods of starting the seed, including direct sowing and germinating them between wet paper towels. The method I’ve settled on I also use for peas. I put 12 to 16 seeds, hilum side down, in potting soil in a 3-inch container and keep them well watered and in a warm place if the nights are still chilly. When they’ve developed two true leaves, not cotyledons, I set then out in a ring around a bean tower, as shown in the photo. Though the seedlings are crowded in the container, they are easily separated at this stage. Some writers recommend giving them a light starter of high nitrogen fertilizer to cover the period before they are capable of fixing their own nitrogen, but I have never found this necessary.

You’ll read on some websites that a single planting will produce through the whole season. That certainly isn’t true in our garden, in part because we have such a long season, starting the first seeds in early March and harvesting as late as early October. Our years of repeat planting without proper crop rotation probably also contribute to the short survival of individual plantings. We make three or even four plantings, the last in the third week of July. As the plants get senile, production drops and the pods become somewhat deformed. At that point I stop harvesting them and allow them to mature enough to supply next year’s seed. I’ll need around 200 seeds for our use and a hundred more for friends and family who have discovered the virtues of this wonderful variety.

Eggplant as a Perennial # 137

For the last decade we have treated tomatoes as a year-round crop, though there is usually a period of low productivity in the late spring and early summer. More recently we have found that some eggplants will survive through the winter and will produce a few fruit, even during the coldest months.

Early in this series of articles, I wrote discouragingly about eggplants because my plants, whether bought from the nursery or grown from seed, produced little and died early, mostly likely from verticillium wilt. In the last decade I had somewhat better success in years when warm weather arrived in July rather than August. Some websites claim to identify disease-resistant varieties, but their recommendations are so inconsistent that I didn’t consider them useful. We had the greatest success with ‘Black Bell.' A plant we started from seed four years ago wintered over and promised a crop the next summer until a gopher attack ended its life.

Two years ago, I bought seed for ‘Night Shadow’ from Twilley. It was described as the “best replacement for Black Bell and Black Bell II.” I started seed in mid-March 2023 and it grew well, producing an abundant summer and fall crop. Surprisingly, it continued to produce decent amounts of fruit through the winter and spring. This year, with the warm weather of August, production has exploded, and I am regularly pruning back the two large plants when they overgrow the paths. In the Asian or African tropics where they originated, eggplants are perennial, and our ‘Night Shadow’ plants look like they could continue to flourish and bear for another year at least. The ‘trunks’ are getting pretty thick and gnarled, so I’ll probably want to replace the plants next year. Some websites in Florida report that the plants can be kept healthy and productive for at least four years.

This year I started seed of ‘Rhapsody’, a variety strongly recommended by Twilley. It is parthenocarpic, meaning that it doesn’t require pollination to develop fruit and will remain seedless, retaining for longer its tenderness and sweetness, so long as it’s not grown too close to another variety. The young plants were heavily attacked by flea beetles, and it was late August before they were tall enough that the new leaves could escape their attention. Flea beetles were not a problem for the ’Night Shadow’ plants that wintered over, though the new growth close to the ground showed the expected damage. The fruit we have had from ‘Rhapsody’ is good but not conspicuously better than what we get from ‘Night Shadow’, probably because we harvest the fruit when it is about half the size of the eggplants you buy in the supermarket.

The photo shows one of our 18-month from seed plants of ‘Night Shadow’. It’s not a thing of beauty and it doesn’t look very healthy, but it churns out excellent fruit almost faster than we can use it or give it away. There’s not much fruit visible in the photo but when you lift the branches sprawling along the ground you’ll be shocked at how much more turns up.

Flower Photography in the Cellphone Era #136

3 - Depth of Field    

The wide angle (x0.5) lens of the iPhone lets you get very close to the subject with a minimum focus distance of about 2 cm. This means that you can take detailed photos of a very small flower. However, even with the very small lens you’ll run into depth of field problems when important parts of the subject are at different distances from the lens. You can mitigate the problem by using a tripod, a delayed-action shutter and a long exposure time with the aid of a third party app like Halide. However, if you want to achieve the greatest detail, you need to use focus stacking, which overcomes the optical limitations of your camera by combining multiple images focussed at different distances from the lens. I’ll tell you about my efforts to use focus stacking on the iPhone which have been somewhat successful.

There are focus stacking apps for the iPhone and I’ve experimented with two of them. The first, called AuraHDR, lets you select a bunch of points on the image, after which it takes a shot focussed on each of them. You then export the photos to your Mac where you can use a focus stacking application like Affinity Photo to create an image combining them. Unfortunately, the app lets you use only the main lens and so it’s not useful for a closeup. It seems to be intended more for improving depth of field in landscape photography, as is demonstrated in their tutorial video. An app called CameraPixels seems at first sight just what I need. It has a “focus bracket” mode that lets you choose a range of distances from the lens and a number of shots to take over that range. You can select the wide angle lens and the nearest parts of the subject appear in focus when you click the shutter. However, when you export the resulting images to Affinity Photo and run the focus stacking software, the final image shows the nearest portions are out of focus. The camera must have defaulted to the main lens. I haven’t been able to change this but it should be easy enough for the developer to fix the problem.

So I am left with having to do the whole process myself, which isn’t difficult once you understand it. You’ll need a tripod and make sure that the clamps are firmly tightened. You want to be sure that the camera doesn’t move even slightly when you tap the shutter button and the screen when you manually select the focus points. Be sure to select a delayed shutter action. Take as many shots as you need to cover all of the parts of the image that you want in focus. I don’t ordinarily take more than half a dozen to cover the distances from the lens that I want to include. The inherent depth of field is enough that you shouldn’t need a greater number.

Once you have enough shots, export the image files to your Mac. You can then use an application that does focus stacking, like Affinity Photo or Photoshop, to generate the final image. The software needs  to do more than identify the best focussed portions of each image and to exclude the parts that are not well focussed. It also needs to correct for the different projection and magnification with varying distances from the lens. The first process is ‘alignment’, followed by smart combination of the images. If alignment of contributions from several images is imperfect then the image on the far right will show ‘ghosting’ as illustrated in this blowup of the stamens of a Geissorhiza.

Here is an example of what you can achieve. I photographed a single flower of the Pink Breath of Heaven, Coleonema pulchellum, which is only 8 mm in diametre. The first is a single shot and the second is the result of stacking five images focussed on different parts of the subject. The lower left petal is not well focussed in either photo because it is too close to the camera lens. You can easily see that the second is better focussed over most of the plant. What you won’t see without blowing up the photo is that there is some subtle ghosting, most noticeable in the leaflets at the lower right corner.

I expect that Apple will add focus stacking to the iPhone camera’s bag of tricks within the next generation or two, and when they do I’m sure they’ll do it right.

Flower Photography in the Cellphone Era Part 2 - Shooting a closeup photo

South African bulbs from the Dawson garden include (left to right) Moraea (aka Homeria) elegans, and Geissorhiza monanthos, both of which bloom for only a few days each spring. The third is a ZygopetalumIn, similar to Z. Redvale ‘Pretty Ann," and bought at Trader Joe's.

In my earlier articles on closeup flower photography, I listed some “cardinal rules” that apply equally to conventional film and to digital cameras. Here they are again.

        1) Work by available light in overcast conditions.
        2) Use aperture priority with the smallest aperture (largest f-stop).
        3) Use a tripod.
        4) Use a neutral background to avoid distracting objects behind the subject.

The advanced software of the cellphone camera allows you to ignore rules 2 and 3 most of the time. For the serious photographer who wants full control of the camera, there are third party apps like Halide that do allow you to adjust variables like shutter speed and aperture, but the modern cellphone is so ‘smart’ that I find no need to use them. As for the tripod, I have a clamp that will let me mount my iPhone. With the delayed shutter action it will let you keep the camera very still and I would expect that would improve results in a very closeup situation. In practice, I’ve found that the image stabilizing software is so effective that I can’t see a difference between hand-held and on tripod shots of the same flower, even when they’re blown up on my 27-inch monitor.

The image stabilization offered by conventional digital cameras uses motion detectors in the lens or in the camera that move either the sensor or components of the lens to compensate for the motion. If the detector is in the camera the lens doesn’t need stabilization. Most cellphone cameras have a gyroscopic motion detector with software that moves the lens to compensate for camera motion. Some of the newer iPhones have “sensor-shift” image stabilization. The advantage of the latter is that it still works if you use one of the third party supplemental lenses available for your cellphone. However, I don’t think you’d want to use one of these for closeup flower photography. Suppliers of cellphone macro lenses extol their shallow depth of field with their “outstanding bokeh effect”. That’s exactly the opposite of what the flower photographer wants, as I’ve explained in the first article of this series.

Image stabilization corrects for motion of the camera but not of the subject. If you are photographing a flower out of doors in windy conditions you will need plenty of light and a fast shutter speed, and this is where the third party apps will be useful. You may also want to use “burst mode” in which a rapid series of shots is taken while you maintain pressure on the exposure button. You can select the one that shows the least effect of motion. Most of the time I move the plants in containers into the greenhouse where I have nice diffuse illumination. You can also snip the interesting part of the plant and position it indoors with a small vice of the type used to tie flies.

Even the best camera sensor can’t match the ability of the human eye to discern detail when there is a very large difference in the illumination of various parts of an image. Under very bright conditions the highlights will be washed out and the shadows uniform black. In the film era, darkroom processes like burning and dodging could mitigate the problem to a degree and analogous tools can be used with software editors to enhance underexposed and to reduce the brightness of burnt out parts of the image. Cellphone cameras use HDR (high dynamic range) software to correct for ‘contrasty’ conditions by combining several shots of the same scene, reducing exposure of the highlights and increasing it in the shadows. This gives you a better photo, but it’s nowhere as good as what you will get with ideal lighting conditions. Therefore I reiterate, do your outdoor flower photography in overcast conditions. Yes, if you’re on safari under a blazing sky in the Namib desert, you’ll have to accept conditions as they are. You may still be able to snip a piece from the plant and move it to a shaded area, or position yourself or a friend so your shadow covers the subject.

As for the fourth item on my list, it’s still desirable to hide distracting items from the background of the photo. I have a piece of black matte poster board that I can prop up behind the subject. After over twenty years of service it has become a bit battered and I find myself having to edit out the scrapes. One of these days I’ll cough up a bit of change for a new one.

Flower Photography in the Cellphone Era #135

Three photos, all taken with an iPhone 14 Pro Max, of plants happily growing at the Dawson home--(left to right), a Miltassia orchid, an intergeneric hybrid of Brassia and Miltonia; and two South African bulbs, a Geissorhiza inaequalis; and Moraea macronyx.

I bought my first digital camera in 2000. It revolutionized my experience with flower photography and I wrote an enthusiastic series of articles on the subject for The Spindrifter in 2002-3. As cameras and the supporting software steadily improved, I produced an updated series of articles in 2007, and wrote a further update on the subject of focus stacking in 2019. Five years later I have given up using my expensive photographic equipment for closeup flower photography. My iPhone produces photos just as good and sometimes better than those I obtained with much greater labour with my latest camera equipment. It’s now fairly easy even for a beginner to get an excellent photo of his favourite garden bloom, but there are still some tricks that may help to improve the results. I’ll share a few of these with you.

I’ve been an Apple fanboy ever since I bought my original Apple II computer in 1980. I was a bit slow buying an iPhone, my first being the fourth generation, and initially I wasn’t much impressed with the camera. Advances in photography were bumping against the laws of physics by the end of the last century, and the improvements of the last two decades are almost all due to better chips and software.This is why computer giants like Google and Apple have stolen the lunch of companies like Canon and Nikon, and it’s why the latest iteration of the iPhone, with its tiny lens and sensor, is able to match the performance of a bulky and expensive digital SLR camera.The small lens gives the cellphone camera one formidable advantage for closeup flower photography because of its inherently greater depth of field, bringing more parts of the subject into acceptable focus, even without the software tricks used to overcome the deficiencies of the optics imposed by the camera’s small size.

My experience with cellphone photography is entirely with the iPhone and I know there are enthusiasts who consider the offerings from companies like Samsung and Google as good or better. I’m sure that you can get excellent results from any recent vintage high-end phone. As they say, “The best camera is the one you have with you," and having a phone in your pocket means that you will take advantage of many ‘photo-ops’ that you would otherwise miss in situations where you don’t want to be lugging around a real camera. This applies as much when you are visiting a garden as at family gatherings. It applies especially in closeup photography where a tripod would be essential with traditional equipment.

So, in what situations is a cellphone inferior to conventional photographic equipment? Well, it obviously can’t match the telephoto capabilities of a 300mm or greater lens, so it’s not the camera for a birdwatcher. It can’t achieve the depth of field that is possible with focus stacking when you’re doing real macrophotography with small flowers. The aggressive processing done by the phone’s software may distort the colours of your flower, though I have rarely found this to be a problem with the latest versions of the iPhone. You can always record a RAW image, an option available in recent versions of the popular cellphone cameras.

Cellphone cameras include ‘apps’ to edit your photos, including third party software capable of doing quite advanced work. I can’t imagine why any serious photographer would want to do editing on the tiny screen of his phone. I immediately transfer my shots to the computer so that I can do the work on a full-sized monitor. There’s almost no photo that can't benefit from a bit of cropping and straightening, and I usually add some adjustment of highlights and shadows and some blemish removal, mostly in the background.

In the next couple of articles I’ll go into more detail, explaining why cellphones are so rapidly making conventional cameras obsolete, and offering tips on how to improve the closeup flower photos taken with your phone.

It’s Time to Order Seeds #133

For the serious hobbyist it’s more satisfactory to grow vegetables from seeds, rather than buying plants from the nursery. You will get a much greater choice of varieties and you will be able to set them out when they are in optimal condition for transplanting. Buying a six-pack of cauliflower seedlings is likely to give you a bunch of root bound plants that will all mature at the same time. You’ll need to give most of them away, discard a few plants or face a glut of cauliflower which is in the best condition to harvest for only a few days and will go off within two or three days of cutting. Most vegetables keep better than cauliflower but they’re all at their best within 24 hours of harvesting. With seeds you can make multiple plantings tailored to your probable rate of use.

I always wait until the new year has dawned to do my ordering of seeds for the next season’s planting. Perhaps it’s just paranoia on my part, but I am never sure that I’m not getting last year’s seed when I order after the summer, especially when those autumn discount sales appear in my inbox.

Over the years, I’ve scattered through these articles' recommendations for specific varieties when writing about individual vegetables, but I thought that it would be useful to bring this information to one place for the interested reader. There are scores, and sometimes hundreds, of varieties available when you go through the catalogues and I have no doubt that many are as good as, or better than, those that I mention here. After all, we have a small hobbyist’s garden, not an experimental farm. However, I can say that those I recommend have done well for us during multiple seasons during more than half a century of edible gardening a few hundred yards from the Pacific.

Beet ‘Kestrel’. More widely available varieties like ‘Red Ace’ are fine but ‘Kestrel’ has proven especially reliable.

Broccoli ‘Packman’. This is an early maturing variety with a nice main head and side shoots that will keep you supplied for many months. We have plants over a year old that we keep mainly in the hope of appeasing the rabbits, but they still supply us with enough shoots to be useful.

Carrot. We’ve grown many of the standard orange carrots and none stands out enough to be recommended. Carrots grow well but in our climate don’t develop the good flavour one expects from the home garden. I can recommend Kyoto Red but it won’t do well unless it is planted in September or October.

Cauliflower ‘Snow Crown’. Early maturing and reliable. Set out two plants every three to four weeks, depending on how much you like this vegetable.

Cabbage ‘Red Dynasty’. Excellent quality and keeps well with storage. The heads are tight enough to resist invasion by slugs and caterpillars, unlike most early green cabbages.

Kohlrabi ‘Conan’. Very reliable and can grow to tennis ball size without getting woody.

Radish ‘Cherriette’. Quick maturing and keeps longer in the ground without getting pithy, compared with some like ‘French Breakfast’.

Rutabaga ‘Laurentian’. Better tasting than the more widely available ‘American Purple Top’.

Pole bean ‘Fortex’. Tops for flavour, though not as vigorous as ‘Blue Lake’, also a good choice.

Bush bean. There’s no clear winner but ‘Contender’ is reliable. ‘Nickel’ is a good French filet, but like all filets, it gets tough quickly if not harvested when first ready.

Fava bean ‘Robin Hood’. Low growing and very productive.

English pea ‘PLS 560’. Tasty and disease resistant. Give it support though web authors say it’s not necessary.

Snap pea ‘Cascadia’. Low growing but also needs support.

Cucumber ‘Sweet Success’. Far surpasses others we have grown for reliability and fruit quality.

Okra ‘Jambalaya’. Reliable and tasty in our hands. It does turn tough if allowed to get longer than about 4 inches and so needs regular cutting.

Tomato ‘Celebrity’. Not as disease resistant as several varieties I’ve discussed recently, but tops for fruit quality and winter cold tolerance.

Winter squash ‘Bonbon F1’. Doesn’t store as well as butternut squash but unmatched for fruit quality. Burgess buttercup is similar and open-pollinated so the seeds can be saved.

You’ll note plenty of omissions from this list. Some, like parsnips, celery and Brussels sprouts, don’t do well or develop good table quality in our climate. Some, like salsify, celery root and witloof, aren’t, in my opinion, worth the considerable effort it takes to grow them.  And then, there is summer squash. Yes, it tastes OK if you dose it with enough salsa, but not good enough to warrant giving it the amount of garden space it requires.

Arthur Dawson

Corn Blotch Leaf Miner #132

Though we have grown sweet corn for decades, it remains surprising to me how successful a crop it is in our overcast La Jolla summers. This year was especially challenging with an unusually cool and rainy spring and early summer. Seeds planted in the first week of March failed to germinate and our first crop was about four weeks late. We were still able to get six harvests, the last in the third week of November. Years of repeated planting in our small kitchen garden has kept us in delicious corn through about six months of the year but also has made us susceptible to an insect attacker that the UC Integrated Pest Management website describes as “not considered a pest." I realize that this is a problem that will be of concern to few readers of this column, unless they share the passion for garden-fresh home-grown corn that I inherited from my Ohio-born American mother. However, it brings up some interesting questions of pest management when there are few effective insecticides still available to the California home gardener.

Leaf miners produce a characteristic pattern of yellow or white trails on the leaves of many plant species. By burrowing into the leaf parenchyma, the larva enjoys a ready supply of food and is less exposed to predators than if it were feeding on the leaf surface. Larvae of many insect species, including beetles and flies, employ this strategy, but most are butterflies or moths. The one most familiar to California gardeners is the citrus leaf miner, a recent introduction from Mexico.

The corn blotch leaf miner is the larva of a small fly, Agromyza parvicornis. It occurs through most of the United States and southern Canada but does not seem to have spread to the rest of the world. It was described as a new arrival to Idaho in 2002 and so it is likely that it’s moving northward as the climate warms. A search on the internet yields publications from many states showing photos of the typical leaf damage but advising against attempts to eradicate it and saying that it is not a significant source of economic loss. I was surprised at this dismissal because it has become a serious pest in our garden, but I realize that we have provided the creature with ideal conditions.

The adult fly lays its eggs on both upper and lower surfaces of the leaves. The newly hatched larvae burrow into the leaves where they progressively elongate and widen their mines until a heavily infested leaf can dry up and shrivel. The photo shows an example of a moderately severe attack. The damage is mostly confined to the lower leaves, perhaps because their thinner cuticle is more readily penetrated. The larvae may pupate within their tunnels and the adult flies emerge from the leaves or, later in the year, the pupae drop to the ground where they can overwinter in the soil. The duration of the larval and pupal stages is affected by temperature and the whole life cycle can last from four to six weeks, meaning that there are probably five generations a year in our climate.

The above explains what we have observed in our garden. We make six or seven plantings of corn each year and the first two show only mild damage. As the season advances, the damage to the leaves increases. As daylight hours diminish, growth slows, resulting in smaller leaves and damage to a greater fraction of the photosynthesizing portion of the plants. Only the last two plantings are so severely attacked that their growth is stunted, and they have fewer and smaller ears.

We generally make the last planting of seeds around August 15 and expect to cut the ears in mid-November. This year I delayed the last planting to August 22 but harvested them at about the same time.

I try to move the plantings away from where corn has recently grown, but that’s difficult in a small garden where we make a dozen or more plantings in a 2-year period. Later in the year the insect can go through two life cycles in the time it takes one planting to mature, so the hatch of pupae will find host plants immediately on hand. I’ve tried spraying with spinosad, thinking that it might kill the eggs before they hatch and burrow into the leaf. I wasn’t impressed with the result and so gave up, not wanting to encourage resistance. I think my best defence in the future will be to spread successive plantings as far apart as possible. It may also help to deep-cultivate the bed before setting out corn seedlings in the hope of burying pupae on the soil surface so deep that they can’t dig themselves out after they hatch.

More about Fusarium-resistant tomatoes #129

In last December's article, I wrote that after an unusually cloudy and cool summer, our standby tomato variety, Celebrity, failed completely and left us relying on the supermarket for fruit from late August to early November. Celebrity is resistant to races 1 and 2 of Fusarium wilt but susceptible to race 3. Hoping to have better success with a tomato variety resistant to all three races of Fusarium, I bought 4 varieties from Holmes Seed, which sells some 10 triple-resistant varieties in small quantities at an attractive price. Would there be at least one that would survive the wilt and share Celebrity’s desirable qualities of flavourful fruit and winter cold tolerance? I started seeds of Camaro, Charger, Amelia, and Mountain Merit on August 17. The first planting was mainly a test of their winter tolerance, and all four varieties did brilliantly. The harvest began in late December and they continued to produce large blemish-free fruit through most of May.

Fusarium is not much of a problem through the winter months and Celebrity plants, which I started around the same time, were similarly productive. All of the plants were heavily attacked by mildew through the winter and, with the return of warmer weather, the mildewed portions of the plants wilted. By May the Celebrity plants had died, as had a couple of the resistant plants. However, the surviving plants of two varieties, Charger, and Mountain Merit, regrew from the still living stems and now, a year after starting from seed, they are producing an abundant harvest.

In the meantime, I had started new seed in January for both Celebrity and the resistant varieties. Having been unimpressed with the taste of the four experimental varieties, I planted seed of another triple-resistant variety called Tasti-Lee. Every source selling seeds for this variety extolled it with claims like, “You’ve seen this breakthrough variety under its brand name in supermarkets everywhere. Now home gardeners can enjoy its fabulous flavor.” Our chilly and overcast spring and early summer delayed the harvest from most of our summer vegetable by four to six weeks. With aggressive hand-pollination I was able to load the new plants with small green fruit, but it was early July before any of them ripened. We were again dependent on the supermarket for a month or so, but for the last eight weeks have been inundated with fruit.

The problem with hand pollinating is that it loads up a plant with maturing fruit and inhibits the appearance of new flowers. In the future I’ll try to pollinate more judiciously, making sure that I have some plants in a condition to form new fruit.

Expecting to lose the January-planted Celebrity after a month or so of harvesting, in late June I started new seeds of Celebrity and of the triple-resistant Mountain Merit. These plants are beginning to set fruit and I hope that they will bear soon enough to avoid the period of autumn dearth that we experienced last year.

So, what is the verdict on the disease-resistant varieties? All have shown excellent winter tolerance and productivity. All have demonstrated superior longevity to Celebrity during the summer months. What about the all-important taste test? So far as Helen and I are concerned, none of them comes close to matching the flavour of Celebrity, but I hasten to add that the blunted olfaction of octogenarians and nonagenarians means that our opinion isn’t worth much. We’ve tried to get a reliable assessment from younger friends and family, but it has proven more difficult than expected. Some, perhaps having experienced only supermarket offerings, proclaimed that all were delicious. Where we did get specific comparisons, our tasters agreed that none was as good as Celebrity. Amongst the disease-resistant varieties there was no winner but a couple of judges gave low marks to Tasti-Lee.

So, I’ll need to continue with regular plantings of Celebrity in order keep us supplied with high-quality fruit for twelve months a year. I’ll need to be careful with the hand-pollination to avoid a feast-or-famine cycle of overproduction like we experienced the last two seasons. Finally, I’ll keep searching for a hybrid that combines triple resistance to Fusarium with quality fruit and the ability to bear through winter in zone 24.
  

Still More About Okra #130

Back in the 1970s we made a couple of attempts to grow okra but gave up after we were rewarded with a few stunted plants that yielded undersized and barely edible fruit. We didn’t try again until a decade ago when we were very successful, as I discussed in a 2014 article. We have grown okra regularly since then, and this vegetable, which we rarely ate in the past, has become a favourite late summer item in our diet. Some of our success may be attributable to our growing experience in edible gardening, but I think it’s mostly due to climate change.

We‘ve tried several varieties of okra over the years, beginning with the traditional ‘Clemson Spineless.’  We’ve settled on ‘Jambalaya,’ which has performed consistently, producing abundant though small fruit. They do quickly become fibrous if the pods are allowed to get longer than about 4.5 inches, so the plants need to be inspected regularly once the harvest gets going.

Some authorities recommend soaking the seed overnight before planting. I’ve found that the seeds germinate readily when started in peat or in 2-inch pots with good potting soil. This year I tried another technique that also works very well with cucumbers. You place the seeds between layers of wet paper towel after wringing out the excess water. Then they are placed in a plastic sandwich bag and set in a warm place. I found that putting them on a rack over the cable modem works beautifully. They need to be watched closely, and the seeds removed and planted in pots when the roots reach about a quarter inch in length which takes only 24 to 36 hours. The great advantage to this method is that sprouts all appear around the same time and you will have a uniform bunch of seedlings when it’s time to set them out. Each year I have started the seed a bit later, and this year I waited until May 20 which I think is about right.

Some years the lower leaves of the young plants are severely damaged by flea beetle. This year there has been no such damage though nearby eggplants are strongly attacked. Most flea beetle species are fussy about their hosts, and it probably helped that I covered the seedlings with hot caps when I set them out.      

No matter how early you plant the seed, okra won’t begin to flower and set fruit until the weather warms up in August. This year the flowers began to appear at the usual time, but most of them dried up without setting fruit. I believe the problem was the scarcity of insect pollinators this year. Okra has a large and attractive flower resembling that of hibiscus. The photo on the left shows a flower a few hours after it opened showing no visible pollen grains on the purple-brown stamens. The one on the right has been visited by a pollinator. I check the blossoms regularly and use a Q-tip to transfer some pollen to where it is needed. Through August and September few of the flowers showed evidence of insect visitors when examined in the afternoon, so I continued my practice of hand-pollinating daily. I’m not certain what would have happened if I had not done so, but we have had an excellent harvest through these months, and I expect it to continue for several weeks until the nights begin to turn cold in late October.

Mealybugs #131

There are some 2,000 species of mealybug, around 170 of them occurring in California. They are true bugs (Hemiptera), in the family, Pseudococcidae, and in the same superfamily as the scale insects. They settle on the leaves and roots of many plant species, weakening them by sucking their sap, and excreting honeydew that attracts ants and supports the growth of black mold. Most confine their attack to a single host but some feed on a variety of plants, some of them ornamental or commercially valuable. Their economic impact is felt mostly by grape growers, thanks to the vine mealybug, which probably originated in Europe and spread widely through the viticulture regions of the world. It appeared in California only 20 years ago. The citrus mealybug is a problem mainly in greenhouses where it is protected from the insects and fungi that limit its spread outdoors.

On superficial examination, the white, sticky clusters formed by mealybug colonies may be difficult to distinguish from other pests like cottony cushion scale or woolly aphids. Mature females at the edge of the colony are easiest to identify. The photo shows what is probably a female long-tailed mealybug, Pseudococcus longispinus, on a Phalaenopsis leaf. As they age, the females exude a waxy protective layer but they do not form a scale.

For the home gardener, mealybugs are troublesome mainly on house plants where they enjoy continuous warmth and the absence of predators, especially if the plants are crowded. Only the tiny males have wings, while the female crawlers are confined to a single plant, so long as it is not touching its neighbour. We have a continuous battle with them on our collection of Phalaenopsis orchids, which has expanded greatly since they have become so cheap at the supermarkets. Most people abandon their Phalaenopsis after the blooms wither but, true to my Hippocratic oath, I feel obliged to keep them going so long as they appear viable. Mealybug colonies appear mostly on the underside of leaves or in the axils between the leaf base and the stem, and can easily escape detection if you don't make a point of inspecting all of your plants every week or so. Given a few weeks undisturbed, they can kill a plant outright or give it a setback that will last for many months. Phalaenopsis languish when the nighttime temperatures drop into the 40's and below so I bring them indoors during the coldest months. It is during that time that mealybug is troublesome. The more vulnerable crawlers and younger members of the colony can be killed by spraying with 70% isopropyl alcohol, but they will soon return. With careful inspection and treatment every week the damage can be kept to a minimum. Once they are moved to a greenhouse in the spring, the pests become less of a problem after a couple of treatments.

Back in 2014, I wrote an enthusiastic article about the new Digitalis hybrid, Digitalis 'Illumination Flame', predicting that it would soon become a favourite perennial in Southern California. Not long after that, I detected a massive attack of mealybug in the roots and on the underside of leaves at the base of the plant. The expensive and beautiful plant quickly succumbed, and we haven't attempted to grow it again. I note that a number of websites, including Annie's Annuals, that vigorously promoted it a few years ago, no longer list it, and I wonder if they encountered the same problem.

Buying Seeds Online: An Update #128

    Two years ago, I had to find new sources of seeds for my preferred vegetables after Stokes stopped selling small packets suitable for the home gardener in the USA. After two seasons of good and bad experience, I’ll share my findings with you.
  After half a century of intensive year-round gardening, our soil is swarming with pathogens. The local fauna, both vertebrate and invertebrate, have discovered a reliable all-you-can-eat station. The abandonment of environment-unfriendly pesticides has left us with only resistant varieties and physical barriers as defences in the endless battle against pests and diseases.
  Though we have settled on a couple of dozen varieties that do well in our garden, none of them can be found in the local garden centres either as packaged seeds or potted seedlings. Few of the online sources can supply more than three or four from our wish list, and, to avoid getting killed on shipping costs, I try to narrow down my ordering to as few as possible. As I explained before, each winter I prepare a spreadsheet matching supplier with variety which helps me to order efficiently. This year I was able to reduce the number to four, and the winner was Twilley’s, a company I had not used before, which supplied nine of the varieties on my list.
  Twilley sells some 1400 varieties which they describe in a well-illustrated catalogue, available both by mail and online. Packet sizes are generous and prices are reasonable. Delivery was prompt and the packets were sturdy, made of metal foil rather than paper. One thing that I found very strange in 2023 is that they don’t provide Amazon-style online ordering. They will accept a telephone order, or you can mail them an order form, but you can’t use PayPal or Apple Pay.
  Another source that I discovered only a couple of years ago is Holmes Seed. They also have a good selection of my favourites, and I’d have ordered more from them if I did not have seed left from last year. One thing I like especially is their packaging. The foil envelope needs to be cut open, but a Ziploc-type seal remains to protect the unused seeds from moisture. This would be especially good if I wanted to store them for more than one season. The packet could be kept in the freezer after adding a silica gel pack.
  Stokes recommended that we switch to Territorial Seed when they ceased selling to home gardeners in the USA. Though Territorial has a big selection, they didn’t happen to supply the varieties we had ordered for years from Stokes. One good thing is that they sell seeds in quantities large enough for the enthusiast whose garden is larger than a postage stamp. Many of the seedsmen will charge several bucks for enough for one small planting and the next size up provides an industrial quantity. For example, Territorial sells peas in 3-ounce packages, enough for multiple plantings over two seasons.
  Harris Seeds sells many interesting varieties, most of them in quantities suitable for the home gardener. Unfortunately, all of those on my wish list were available only in large packages containing far more than we could use. However, it’s certainly worth a trip to their website to see what is available.
  Some of the companies I’ve recommended are family-owned and relatively small, but they are not the places to look for something unusual. Last year I was able to order asparagus pea seeds from Pinetree Garden Seeds. I hadn’t grown them since Thomson & Morgan stopped selling in this country a decade ago. There are many small seedsmen where you can find something special but you can expect it to be expensive, sometimes 10 bucks or more for shipping and handling added to the price of one small packet. Imagine my surprise, then, when I ordered a single packet of cucumber seed from Jay Tracy’s, “The Cucumber Shop,” that I read about in a recent New York Times article. I expected there would be a rush on his small operation, but the highlighted variety, Carosello Leccese Striped, was still available. For $4.42 I received a generous packet of seeds which came by first-class postage with a handwritten address. As if that weren’t enough, it included a free package of heirloom tomato seeds.

Elephant Garlic #127

  More than 50 years ago we were given a couple of elephant garlic bulbs. We planted them in an out-of-way corner of the garden, and they have come up every spring since then, dying out in the original location but surviving in two other untended areas.
  Allium ampeloprasum, or wild leek, is native to southern Europe and western Asia. Its cultivated varieties include var porrum (garden leek), var ampeloprasum (giant garlic), and var sectivum (pearl onion).  A. ampeloprasum var babingtonii grows both wild and cultivated in the British Isles and is used mainly as an ornamental, but it has been a source of food from early historic times. An English source of bulbs intended for the table claims that their stock is descended from plants introduced to Cornwall by Phoenician traders. The debate about the “botanical status” of elephant garlic is discussed in an article by Colin Simpson in NVS News, a newsletter of the English National Vegetable Society. It dismisses a claim made in the 1970s by “one United States seed house” that they had bred it by crossing an onion with a leek. The distinguished English botanist, Martyn Rix, regards it as a hexaploid form of wild garlic, which may partly explain the large bulb. James R. Bagget of the University of Oregon, another well-known hybridizer, classifies it as a separate species, A. scordoprasum. There does seem to be agreement that the elephant garlic now grown for the table in North America is descended from bulbs collected by Jim Nichols, founder of Nichols Garden Nursery in Philomath, Oregon. Simpson, who sells some of his bulbs to restaurants, obtained his stock from Nichols.
  As explained on the Nichols website, the first bulbs were collected in 1941 from farmland in the Willamette Valley, originally settled by immigrants from Bohemia. Over the next dozen years, the bulbs were propagated, and the best bulbs were selected to improve the stock. In 1953 they began to sell what had been known as giant garlic under the name, “Elephant Garlic.” The website gives detailed instructions on how the bulbs should be grown, recommending a well-drained soil and a cover crop, like buckwheat, to be grown before the bulbs are planted. They stress the importance of preventing competition from weeds. That may explain why our garlic grows best in a path between raised beds covered by walk-on bark.
  A mature bulb, which can measure up to six inches in diameter can, like garlic, be separated into several flat-sided cloves. On its surface will be some bulblets, less than an inch across and too small for the table. If you plant these, in a year they will produce “rounds” measuring less than three inches, which can be harvested or left for another year to become multiple cloves.
  Elephant garlic is much milder than true garlic and does not substitute for the latter in the kitchen. Some internet sources extol elephant garlic soup, but in our experience it’s pretty insipid without a lot of help from other ingredients. Most of the recommendations are for roasted cloves, and that’s the manner of cooking that we’ve found most satisfactory. The many posted recipes advise wrapping the cloves with tinfoil and roasting for up to an hour. Then you cut the thick skin of the clove and squeeze the soft interior onto toast or use it as a garnish on vegetables or meat.

Are ‘Green’ Potatoes Dangerous? #126

  My wife, Helen, recently asked me if there would be any risk in using some potatoes that showed greening of the skins, and I responded, “None whatever.” My answer was based on the research I did for an article in this column 18 years ago in which I wrote, “Potatoes produce solanine, an alkaloid with similar toxic effects to atropine. There is only a small amount in the tubers, but potentially dangerous quantities are present in the tops and in the skin of the tubers if they have experienced ‘greening’ either because part of the surface was above the ground before harvest or because they have been exposed to light during storage or display. The amount of solanine present in green parts of the plant can be lethal when injected into animals but is usually harmless when eaten. Solanine is rapidly broken down in the stomach and is poorly absorbed from the gut. This probably explains the rarity of reports of potato poisoning in humans and farm animals although a few cases have occurred. Green potato tops are eaten by members of the English Bangladeshi community, apparently without ill effects.” Hmm, maybe it would be a good idea to have another look into the question.
  My first thought was that if potato greens are a dietary item for the Bangladeshi diaspora, I should be able to find some recipes for their preparation on the internet. I soon learnt that all references to potato greens were to sweet potatoes, which are commonly eaten in Asia, Africa, and the American South. Reports on their palatability ranged from ‘delicious’ to ‘mild and somewhat bitter.’ The reason that ‘Irish’ potatoes are not eaten, apart from their reputed toxicity, is that they are extremely bitter, and this may also explain why there are so few reports of poisoning. I then realized that my reference to the appetite of the Bengalis for potato greens came from a single source, an otherwise excellent study examining the toxicity of green potato tops and their principal ‘glycoalkaloids’ (GAs}, alpha-solanine and alpha-chaconine (Phillips BJ et al. A study of the toxic hazard that might be associated with the consumption of green potato tops. Food Chem Toxicol. 1996 May;34(5):439-48.) Evidently, the authors didn’t realize that the Bengali delicacy was the sweet potato. They administered homogenized potato tops by gavage (tube feeding) to rats, mice, and hamsters and observed no ill effect. Injection of ana-solanine/ a-chaconine mixture was lethal to hamsters within 24 hours while the same amount given by gavage for three days was harmless. So, in hamsters, at least, a potentially fatal dose of GAs is poorly absorbed from the gastrointestinal tract.
  What are we to make, then, of reports of human poisoning by green potatoes? In the first place, considering how ubiquitous potatoes are in our diet, such reports are extraordinarily rare. Some of them can be dismissed as questionable, such as this recent one from Saudi Arabia. An eleven-year-old boy presented to the emergency room with colicky abdominal pain and vomiting of greenish material. His mother reported that she had been too busy to respond immediately to his complaint of hunger and he ate some raw potatoes in her absence. During an eight-day stay in the hospital his heart rate dropped to “less than 60 beats per minute,” as shown in an ECG that was mounted upside down (Al Masaoud et al. A challenging case of suspected solanine toxicity in an eleven-year-old Saudi boy. J Family Med Prim Care. 2022 Jul;11(7):4039-41.) In other cases of suspected solanine poisoning, if the heart rate was mentioned, it was described as rapid.
  The best documented report of human poisoning occurred at a London day school where 78 junior students developed diarrhoea and vomiting after eating potatoes. Seventeen required hospital admission for up to 11 days. Other symptoms included fever and abdominal pain and, in some of the most severely affected, stupor and circulatory collapse. Senior students and staff who had the same meal experienced no illness. Solanine poisoning was confirmed by showing reduced plasma pseudocholinesterase levels in ten boys and by showing large amounts of GAs in waste material from the meal. All of those who became ill had consumed potatoes from a small bag left over from the school summer term, some three months earlier (McMillan M, Thompson JC. An outbreak of suspected solanine poisoning in schoolboys. Q J Med. 1979 Apr; 48(190):227-43.)
  What about fatal human poisoning? There was one convincing report of a family of nine in Indiana that consumed greened potatoes that had been exposed to sunlight over three days. All became sick except a child of 18 months who was fed little but milk, and the father who did not eat the tubers. Two of the family died. (Hansen AA. Two fatal cases of potato poisoning. (Science. 1925;61(1578):340-1.) The only other report of death from solanine poisoning occurred in a five-year old child who consumed berries of the black nightshade (Alexander RF et al. A fatal case of solanine poisoning, Br Med J, 1948 Sep 11:2(4575):518.)
  So, my statement that there is no risk in eating greened potatoes must be withdrawn. However, I think it is safe to say that you can use them if you cut away the greened parts. The GA content of the tubers is affected by storage conditions but also by the variety of potato, and those grown commercially have been selected for low production. A potato cultivar called Lenape was released in 1967, showing great commercial promise because of its resistance to insects and diseases, and also a low sugar content that made it desirable for producing chips. Unfortunately, the tubers contained some three times the GA content of other varieties and it was removed from the market three years later.
 

Noble False Widow Spider #125

I noticed a spider sitting on one of my orchid plants. I wouldn’t have bothered photographing it, but it was well posed for a shot and my new iPhone is wonderful for macrophotography. I posted the photo on Facebook where my biologist daughter identified it as Steatoda nobilis, the noble false widow spider. I’ve written in the past in this column about widow spiders, but false widows were new to me. A bit of research on the internet turned up a fascinating tale of biological globalism.

S. nobilis is native to Madeira and the Canary Islands but has been introduced widely, initially to coastal areas of the British Isles and the Mediterranean littoral, travelling on imported fruit and plants. There are questionable reports of it arriving in England as early as 1879, and it was permanently resident in Britain by 1907. Specimens were collected in the harbour of Hamburg in the 1950s, but there was no record of established populations in Germany until 2013. Surprisingly, it was recognized nowhere in the New World until a 2011 report by Dr. Richard Vetter who identified a specimen collected in Ventura County. By 2020 it had been found in all the coastal counties as far north as Marin. In 2014 there were the first reports of its occurrence in Chile and Ecuador.

Most of the specimens collected round the world have been in or near human habitations in urban environments. It is described as “synanthropic,” but perhaps that is in part because the individuals who have collected and reported them live in cities. It seems to enjoy structures such as fences, light fittings, and window frames that provide a rigid architecture suitable for building a web. It has colonized much of England and Ireland, with outliers as far north as the Orkneys. Collections elsewhere in the world have been mainly within 10 kilometres of the coast. Though this may be explained partly because of its early introduction to the British Isles, press headlines such as “Britain’s only venomous spiders are invading our homes” and “UK shudders as venomous spider creeps across Britain” have also contributed. There is a close correlation between newspaper coverage and the number of S. nobilis recordings.

Some observers have attributed its recent spread to global warming but, if that were the explanation, one would not have expected Britain to be colonized earlier than the countries of southern Europe. Others have suggested that a mutation, perhaps originating somewhere in the British Isles, has augmented its ability to spread into new environments.

So, is the false widow really venomous? The venom of S. nobilis contains ‘latrotoxins,’ neurotoxins similar to those produced by widow spiders of the genus, Latrodectus. Only a handful of case reports on S. nobilis bites are to be found in the medical literature, few of them with serious consequences. A study from Ireland suggested that some of the severe local reactions were due to the introduction of bacteria at the site, rather than to the venom itself. It is likely that mild envenomations are very much underreported, but considering how common the spider is in Britain, and the anxiety provoked by the press, their scarcity is reassuring. I suspect that the situation is similar to that of the brown widow, Latrodectus geometricus, in San Diego. I can find webs in the handles of our trash barrels any time I care to look, and when I do see a spider it’s usually a brown widow, but I’ve never experienced what I thought might be a spider bite.

The venom of black widow spiders is some 15 times more potent than that of a rattlesnake, and it is capable of producing serious symptoms, even death, in humans. This would seem a gross example of ‘overkill’ for a predator whose normal prey is insects and other small arthropods. However, there are convincing reports of S. nobilis capturing and feeding on animals as large as a bat and a lizard. These may be more than chance occurrences because analysis of components of the venom have shown that alpha-latrotoxin, found in both Steatoda and Latrodectus, is “vertebrate-specific,” meaning that its neurotoxic effects are absent in invertebrates.

I’m surprised that our local media haven’t jumped on this story which offers the possibility of clickbait headlines similar to those that captivated the British reading public.

Afila Peas #124

Peas have been a major food crop for both humans and livestock since Neolithic times. Most of the world’s crop is in the form of ‘field peas,’ grown to be consumed as the dried seed. The plants originally grew as weak-stemmed vines, which needed support to prevent them from ‘lodging’ or blowing over in windy conditions. Lodging made the pods more difficult to harvest and more susceptible to damage by pests if they were in contact with the ground, but providing support added a significant expense to the grower.

Plants with the recessive afila or ‘af’ gene were shorter than normal and produced fewer leaves but an abundance of tendrils. The afila plants were much less susceptible to lodging because of their reduced height and because the plants could support each other by interlocking their many tendrils. With their smaller size and leaf surface, the afila plants were also less productive, but over the last few decades the breeders have developed varieties with greater yield and improved disease resistance.

English or garden peas, developed to be eaten green, were a more recent introduction first described in Western Europe in the 17th century. They account for only a small fraction of the total production of Pisum sativum, but in the last few years several afila varieties of garden peas have been introduced. I have grown two varieties of afila peas, not because I was looking for them particularly, but because all the varieties resistant to races 1 and 2 of Fusarium oxysporum f.sp. pisi (Fop) that I could find were afila.

Because “resistance to Fop is conferred by single race-specific genes,” we shall probably see resistant varieties of taller vining garden peas before long. The breeders will be kept busy because races 5 and 6 are geographically widespread and are already economically important in the Pacific Northwest. It should be possible with gene editing technology to whip up an afila plant resistant to as many races of Fop as you wish in short order. Public resistance to GMO products would make that difficult but, once the genes have been identified, it shouldn’t take too long to construct a bespoke plant by traditional methods of propagation.

I now have two years of experience with afila garden peas, mainly with PLS 560 from Territorial Seeds, but also with one planting of PLS 566 from Harris Seeds. Pure Line Seeds is a family-owned wholesaler breeding some of their own varieties (presumably those called PLS) and distributing others from selected growers in the Columbia River Basin.

Of the five plantings I have made, only one has been really successful, but I have learnt a few things that will, I believe, ensure better results in the future. I usually made a planting of around 50 seeds for vining varieties like ‘Legacy’ and ‘Bolero.’ If they escaped disease, they would produce enough of a harvest to supply half a dozen or more meals for the two of us plus a big mess of pea soup. The afila plants are small, most of them no more than 18 inches. The healthy plants set pods at about the same rate per inch of height as the vining varieties, which means that you’ll need to plant close to twice as many seeds to get the same yield.

The two varieties I have tried seem less tolerant of warm weather than the vining types I have grown in the past. Plantings started at the end of August and in mid-September are less happy than one begun in mid-October. Finally, the plants need to be kept off the ground. Those that fail to connect their tendrils to a neighbour show small and deformed pods, so some help may be needed to guide them in the right direction. The October planting was about 80 seeds which are now flowering and promise an abundant harvest. Part of the success of the later planting may be explained by the fact that Fop doesn’t flourish when the temperature is below 70°. The resistant strains are described as “highly resistant,” but the resistance may not be absolute in our intensely planted and pathogen-rich raised beds. The survivors of the earlier plantings are showing signs of recovery, now setting additional flowers and pods.

For years I started pea seeds between two layers of damp paper towels, setting them out when the root reached about a half-inch in length. I’ve turned to another method that is even more successful. I start 16 seeds in potting soil in a 3-inch plastic container, setting the plants out when they are a couple of inches in height. At that stage the roots separate easily, though the tendrils of the afila varieties may need a bit of disentangling.

So, how do these varieties rate for taste? I’d give PLS 560 a B+ and have held judgment of PLS 566 because the only planting that I’ve matured was grown under adverse conditions. The Cornell Cooperative Extension made reports on pea variety trials in 2020 and 2021. In 2020 they rated PLS 560 at 4.5/5.0 for taste but in 2021 gave it only 3.8. PLS 566 rated 4.0 and 3.5 in the same trials. The top-rated variety in 2020, scoring 5.0, was PLS 534, but in 2021 it scored only 3.8. Evidently tastiness is susceptible to cultural conditions and perhaps also to differences in the tasting panels.

The photo above shows the self-supporting afila, PLS 560, on the left and the snap pea, Cascadia with its support.

Disease Resistant Tomatoes #123

This year our cloudy, cool summer provided ideal conditions for mildew and other fungus diseases of the nightshade vegetables. For example, the Black Bell eggplant provided us with fruit though the winter during the past two years. This year, however, plants started from seed in February died in July before producing any harvest. Tomatoes were nearly a complete failure in August through October, and we were buying supermarket fruit, something we haven’t done in years.

In the past, articles on the internet on how to prevent Fusarium and Verticillium wilt on tomatoes emphasized cultural practices like providing good drainage, avoiding overwatering and crowding of plants, and a 4-year crop rotation of nightshade plants. An additional recommendation, that I’ve seen only recently, is to use calcium nitrate instead of ammonium-based fertilizers as a source of nitrogen. Of late, however, we are seeing more experts admitting that these methods are not very effective, and the only solution to fungus diseases is to grow resistant varieties. Seedsmen, mainly those selling to commercial growers, are providing much more specific information about which diseases a variety can tolerate.

Though home gardeners lack the facilities to diagnose the diseases affecting their plants, they can make a pretty good guess from the symptoms shown by the plants and by the varieties that fail to prosper. In our case, I believe the main threat to our plants is Fusarium oxysporum sp. lycopersici, races 2 and 3. It is troublesome during the summer, and plants that survive through September may recover in the late autumn. The most characteristic symptom is yellowing, then browning and blackening of the lower leaves and branches of the plant. Growth slows and the disease advances upward until the plant dies or, more likely, is euthanized by the unhappy grower.

We had to give up growing heirloom tomatoes many years ago. For a while we succeeded with varieties such as Big Boy, Better Boy and Early Girl. For the last couple of decades, we have grown Celebrity almost exclusively, recognizing that we would need two or three plantings to carry us through the summer months, though seeds started in August would supply fruit through winter and the following spring.

Last year I read about Celebrity Plus, advertised to provide the good qualities of Celebrity with “an enhanced resistance package.” This year I made three plantings of both Celebrity and Celebrity Plus, starting them at the same time and growing them in the same beds. The seeds started in February, which should have supplied our summer main crop, gave up in July after providing three to six tomatoes, plus a few stunted fruit on the upper branches. The April planting looked sick and supplied almost no fruit, only beginning to perk up in late September. I could see no difference in the disease susceptibility of the two varieties. The one important difference was that Celebrity Plus produced few flowers and set little fruit, even with hand pollinating. The “enhanced resistance” of Celebrity Plus is to tomato spotted wilt virus, seemingly not a problem in our garden. Both varieties are resistant to races 1 and 2 of Fusarium, which led me to conclude that I need to find a variety resistant to race 3.

I haven’t seen anything written about it, but a symptom of Fusarium on plants that seem otherwise to be recovering is lack of flowering and a failure of the flowers to set fruit, even with hand pollinating. As the fall season advanced, Celebrity Plus showed an increasing abundance of flowers and in late November is beginning to hold its fruit.

Cornell University has a website giving details about disease resistance in over 600 tomato varieties. They identify about 25 that are resistant to all three races of Fusarium wilt. Only a fraction of these are supplied by the major online seed sources, and the smallest quantity sold of some of them may set you back 20 dollars or more. Holmes Seeds is a good source if you want to experiment with a new variety because they have a uniform price of $2.75 for starter packets of most of their seeds. In the case of tomatoes, that small sum will get you only five or ten seeds of some of their hybrids, but that’s enough to give them a test. They had ten varieties of slicers resistant to all three strains, and I ordered Amelia, Camaro, Charger and Mountain Merit, choosing them by the eeny-meeny-miny-mo method. I planted two seeds of each on August 17 and, three months later, I can give a preliminary report. Seven seeds came up and all the plants are flourishing. All are setting fruit, aided by hand pollinating, at least as well as Celebrity, and much better than Celebrity Plus. As I write on the last day of November, each plant has at least 20 fruits and some are beginning to colour up.      

This experiment, planting the seeds when the plants will mature in the cold months, is mainly a test of their ability to bear through the winter. I’ll start a second round of seeds in February to test disease resistance and further evaluate fruit quality. It may turn out to be one of those “choose any two” situations. I’ll recruit the family for a taste-off of both winter and summer fruit and hope to announce the winner(s) in the fall.