Vegetables – Page 19

In some gardening circles, a gardener’s worth is measured by how well he or she grows peas: how soon the first pea gets to the table, the crop’s abundance, and, of course, the flavor. Sad to say, I haven’t been able to grow peas well for about 10 years.

Peas require a humus-y, moisture retentive soil and early planting, all of which I provide. But about 10 years ago, just as the crop was coming on strong, vines began to turn yellow, leaves would flag, and plants would die. The probable cause was fusarium wilt disease (caused by Fusarium oxysporum). This soil-borne fungus invades plant roots and then clogs up the vascular system.

(You may have heard of fusarium wilt of tomatoes and other vegetables. Fear not spread of fusarium among these vegetables, because different vegetables have their own fusarium subspecies. Cucumbers have F. oxysporum f.sp. cucumerinum, canteloupes have F. oxysporum f.sp. cubense, and peas have F. oxysporum f.sp. pisi. How cozy.)

Fusarium wilt probably never made it past my garden gate. It was probably already in my soil at some low level. Over the years, I’m guessing that it built up to a critical mass and was inadvertently spread — by me — on trowels, boots, and tellising. Which leads to one way to keep the disease in check: Clean trowels before planting peas; clean hoes before hoeing peas; and clean or torch the chicken wire trellises and metal support posts that keep the vines off the ground.

Some pea varieties are resistant to fusarium disease. But there are a few races of the disease. A variety resistant to one race may be susceptible to another race. Planting a resistant variety one year did not ratchet up my “good gardener rating.” The plants succumbed to the disease as in other years, and understandably so since I did not know which fusarium race I was up against, and variety descriptions for wilt resistant peas don’t always specify to which wilt race the variety is resistant.

Fusarium conquered(?)

This year I’m back in the game again with peas — and an excellent harvest it is: abundant, early, and flavorful! (These are shelling peas, which take longer to mature than snap peas or snow peas, but also taste better even if they do need shelling.)

One thing that I did this spring — the thing that I’m touting as responsible for my good crop — was to plant the pea seeds in my south vegetable garden, where I haven’t grown peas for the past 6 years. My wan efforts over the years have been plantings in my north vegetable garden, and they have been consistent failures.

F. oxysporum f.sp. pisi survives from year to year in the soil as spores, very hardy spores. So hardy that the recommendation is frequently made not plant peas again, ever again, in tainted soil. Other recommendations are to wait 5 or 10 years before replanting. In either case, of course, it’s necessary to be very careful about spreading the disease again on tools, boots, or trellises.

And again, the ideal would be to plant disease resistant varieties.

Good rotations

People sometimes ask me if I rotate my crops each year. Crop rotation does not involve twirling plants; it’s moving certain plants — be they in a botanical family or part eaten — to different parts of the garden each year.

Sammy, the pup, guarding garden beds

In the case of plant families, it’s a way to reduce pest problems because family members may host the same pest (clubroot disease of broccoli, cabbage, turnips, and radishes, for example). A pest that overwinters in the ground will eventually starve if a suitable host is not on hand on which to feed. A pest that flies or that shoots spores far and wide can travel some distance to find a host, but that, fortunately, is beyond the capacity of many pests.

In the case of rotating by part eaten, such as leaf, fruit, or root, the idea is to balance nutrient uptake. Leafy vegetables are hungry for nitrogen, root vegetables for potassium, and fruiting vegetables for phosphorus.

It’s generally safe to rotate vegetables on a three year cycle. That is, not to return a vegetable in the same family or with the same part eaten to the same place sooner than within 3 years. Planting in beds makes this easy because once the garden is planned out, you just move the crop to the next bed, or two beds away for further distance, each year.

Do I rotate my crops? You betcha’. With peas, I’ll try the 3 year rotation in the south vegetable garden. And I’ll wait at least another 5 years before planting them again in the north vegetable garden, then giving the south garden a “rest” from them. It’s good to again be unzipping green pods and scooping out the sweet peas within.

Cold has yet to throw a wrench into salads fresh from the garden — even though December 16th saw a night-time low of 12°F. Yes, the lettuce would be mush if unprotected but under the sheltering clear plastic and wooden sides of my 5 foot square cold frame, the plants are barely scathed. Just a few leaves wilted at their edges. Spinach that I sowed between the lettuce plants, for harvest after the lettuce is finished is still looking spry.

Plastic tunnels supported by wire hoops are offering almost as much cold protection over 3 garden beds. Beneath them, mustard greens, endive, and arugula don’t exactly thrive, but do survive.

A few fresh greens are even surviving out in the garden without any sort of protection whatsoever. That would include some arugula that was never covered as well as kale, what’s left of it, and mâche, the most cold-hardy of all salad greens.

Once temperatures plummet or the ground is blanketed with snow, fresh salads will come from the greenhouse, which, with night temperatures never allowed to drop below 37°F., is packed with lush greenery as if it were May.

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Update: Lettuce in the cold frame is flagging after a night-time low of 8° a few days after that 12° low. Unprotected out in the garden, only mâche and kale survive.

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The holiday tree, only a half a foot tall and ornamented with 3 silver balls, is cute as a button. It’s a Norfolk Island pine (Araucaria heterophylla), a free gift I received a couple of weeks ago from a mail-order nursery. This tree will green up the darkest days of the year for year after year because it’s a tropical species that does well in the eternal warmth and somewhat dry air, in winter at least, of any home.

Over the years, the tree will lose its impishness and develop a straight, upright trunk off of which will grow relatively widely spaced, whorled tiers of horizontal branches, all clothed in green needles. With age, the plant becomes quite majestic. Too majestic, in fact, for any home. I have seen the spreading branches of this tree towering 40 feet or more over the tiled roofs of homes in tropical climates.

So what’s a gardener to do with such a plant, after years of nurturing it and watching it grow? One option, of course, is to bite the bullet and walk it over to the compost pile. Or it could be gifted to a friend with a higher ceiling, but that just shifts responsibility and puts off the inevitable. How about giving it to grandma for her front lawn in Florida?

A natural inclination for any real gardener in this situation would be to try to keep the plant going, not as its original self but in the form of a cutting. The rooted cutting, then, is genetically the same as the original plant, only a smaller version. Norfolk Island pine does root from cuttings especially, as with many conifers, if the cuttings are taken from young growth.

This plan has one problem: fixed plagiotropism. This botanical mouthful signifies the tendency for a horizontal shoot of certain plants to always retain its horizontal growth habit. Put more simply, if a cutting is rooted from one of Norfolk Island pine’s horizontal stems, that stem will always grow sideways to creep along a windowsill or wherever else the plant is growing.

The solution to this problem is to take a cutting from the leading, upright stem. It the mother plant isn’t destined for composting, though, cutting out that leading stem does ruin its form. Also, because young cuttings root best, you might end up with only one cutting, perhaps two, from that short length of young, leading stem. Not much insurance for a plant that doesn’t root all that easily.

The leading, upright stem, of a plant can have the opposite inclination: fixed orthotropism, a permanent, upright growth habit. With other plants, their plagiotropism or orthotropism may be temporary.

Not so for Norfolk Island pine’s plagiotropism. I’ll figure out how to cross that plagiotropic bridge, or not, when I come to it.

(For further discussion of topophysis, which encompasses plagiotropism an orthotropism, and related topics on plant growth, see Plant Form: An Illustrated Guide to Flowering Plant Morphology by Adrian Bell and Alan Bryan.)

Peas Please Me

Fusarium conquered(?)

Good rotations

SALAD TUNNELS & COLDFRAMES, AND INDOOR “PINE”