“Worms” Good and Bad
Nematodes Galore
The name ”nematode” doesn’t conjure up a creature that you’d normally want to make friends with. It’s other name, roundworm, seems even more repulsive and is, in fact, also a name applied more specifically to a nematode that infects humans and dogs.
Like it or not, nematodes are all around us, with over 25,000 species described so far that inhabit diverse ecosystems from thousands of feet deep in the Earth to mountain tops, and from deserts to rain forests. Many are visible only under a microscope; some are two inches long. A square yard of soil can be home to more than a million nematodes, and we humans can be host to about 35 species.
Do we want our plants to cozy up with them?
A number of nematodes infect plants, resulting in stunted growth and, often, swellings on roots or stems.
Soybean cyst nematode
Their common names — root knot nematode, stubby root nematode, cyst nematode, lesion nematode — describe some of the symptoms. These plant pathogenic nematodes can do further ill by transmitting bacterial or viral diseases to plants.
I’m not particularly worried about nematodes in my garden. For one thing, they’re more prevalent in warmer climates. Also, good gardening practices, such as enriching the ground with compost, leafy mulches, and other organic materials, and crop rotation go a long way to thwarting such problems.
If I did have a nematode problem, or suspected one, I could reach into a quiver of “organic” solutions. Marigolds can suppress nematodes. Not just a plant here and there, though, but a solid planting of giant, African marigolds. Mustard has a similar effect, whether grown, like the marigolds, as a cover crop, or applied as a seed meal, which also happens to be a slow-release nitrogen fertilizer.
Chitosan, made from the shells of crustaceans and the active ingredient found in commercial products such as Serenade, reputedly bolsters plant defenses against nematodes and other pathogens. (My casual experimenting with Serenade against apple diseases found no benefit.)
Welcome “Worms”
In the same way that just about no one with an eye patch is a pirate, very few “nematodes” are bad guys. In the garden, so-called “predatory” nematodes are better than neutral; they are the “good guys,” preying on a wide range of garden pests.
Some of the most common beneficial nematodes are Steinernema carpocapsae, S. feltiae, and Heterorhabditisheliothidis bacteriophora. These three nematodes vary in their habits although they all attack a wide variety of garden pests. Steinernema carpocapsae is an “ambusher forager” that lies in wait near the soil surface for unwary pests to wander past. Heterorhabditisheliothidis bacteriophora is a “cruise forager” that moves around through various depths of soil, ready to pounce upon unsuspecting sedentary pests. The habitat and hunting behavior of S. feltiae nematodes is intermediate to the other two.
Waxworm releasing beneficial nematodes
Beneficial nematodes can be purchased. To be effective, they must be shipped at the right growth stage and applied without their drying out. Even then, annual applications are frequently needed.
Some strains of the beneficial nematodes can survive and multiply in the soil year after year. I imagine that my garden soil has plenty of “good” nematodes; perhaps more would be better. Some day I may extract some of the “good guy” nematodes from my soil, multiply them, and then re-apply them to my ground.
For now, I intend to get hold of a starter supply of native, perennial nematodes and multiply my holdings, a process which I think will have the added benefit of being fun and interesting. The three kinds of nematodes extracted from soils in central New York, are available for purchase from http://blogs.cornell.edu/ccefieldcropnews/2018/02/28/discount-available-on-biocontrol-nematodes-to-protect-alfalfa-corn-crops/.
With nematodes in hand, a nematode host is needed if I’m going to multiply them. Waxworms, sold for fishing bait, are a convenient host. The waxworms get incubated with the nematodes which, after a couple of weeks, are rinsed free of the waxworms with water.
The aqueous suspension of nematodes is then ready for application. To prevent their drying out, they’re best applied in early morning or evening along with plenty of water. If all goes as planned, they should establish and multiply to kill such pests as wireworms that bore into carrot and radish roots, plum curculio that attack apple, plum and peach fruits, and any cutworms that attack just about everything.
Come Visit My Farmden
Last minute notice: Come visit my farmden, in real life, on June 24th. As part of the Garden Conservancy Open Days program, I’ll be hosting visitors between 1 pm and 4:30 pm on that day. For more information about my farmden and other local sites, go to the https://www.gardenconservancy.org/open-days/open-days-schedule/ulster-county-ny-open-day-2.
Invaders
Dare I Speak the Name?
As I was bicycling down the rail trail that runs past my back yard, I was almost bowled over by a most delectable aroma wafting from a most despised plants. 
The plants were autumn olives (Elaeagnus umbellata), shrubs whose fine qualities I’m reluctant to mention for fear of eliciting scorn from you knowledgable readers.
Yet, you’ve got to admit that the plant does have its assets, in addition to the sweet perfume of its flowers. Okay, here goes: The plant is decorative, with silvery leaves that are almost white on their undersides. And the masses of small fruits dress up the stems as they turn silver-flecked red (yellow, in some varieties) in late summer. 
Those fruits are very puckery until a little after they turn red, but then become quite delicious, and healthful.
(I included autumn olive in my book Uncommon Fruits for Every Garden, and also planted them — but that was before the plant became illegal here.)
Another asset of autumn olive is that it actually improves the soil, converting air-borne nitrogen, which plants can’t use, into soil-borne nitrogen for use by autumn olives and nearby plants.
This native of Asia, introduced into the U.S. almost 200 years ago, was promoted in the last century as a plant for wildlife and soil improvement. Decades ago I worked for the USDA in what was then known as the Soil Conservation Service (now the Natural Resource Conservation Service), an agency that not only promoted the plant but also developed varieties for extensive planting.
Autumn olive likes it here and has invaded fields throughout the northeast, the Pacific northwest, and even Hawaii. It’s an invasive plant. Don’t grow it! (But feel free to enjoy its aroma, its beauty, and its fruits.)
One of My Favorite “Invasives”
As autumn olive blossoms fade, the temporary vacuum in sweet-perfumed air will be filled by another plant, black locust (Robinia pseudoacacia). That aroma comes from the white blossoms that dangle in chains like wisteria blooms from this tree’s branches.
Like autumn olive, black locust has other assets in addition to those offered by its blossoms. It’s a leguminous plant, like peas and beans, so, with the help of bacteria residing in its roots, also puts air-borne nitrogen into a form utilizable by plants.
Black locust’s other assets refer to it when dead: The dense wood is very resistant to rot — much, much more so than cedar — and is very high in BTUs for burning. I converted all my garden’s fenceposts and arbors, which I had previously made from cedar and lasted only about 10 years, to locust.
I’m lucky enough to have a mini-forest of them growing along one edge of my property. I cut them when they are five or six inches in diameter, and in 10 or so years I have a new one to replace the cut one. It adds up.
Quick growth and the ability to resprout from stumps and grow in poor soil by “making” its own nitrogen makes black locust, like autumn olive, a plant not loved by everyone. Despite being native here in the U.S., black locust has been classified as a “native invasive.” The reason is that it was originally native to only two regions in the U.S., from which it has now spread far and wide.
Change Will Come
The classification of “native invasive” highlights the capricious legality and classification of invasive plants. Where is the boundary within which a plant becomes an accepted native? In the mountain that rises up just behind my valley setting, lowbush and highbush blueberry are thriving natives. But these plants would never turn up here on my land, except that I planted them. (And both thrive.)
Clove currant is another plant I grow, one that, in addition to bearing spicy fruits, is resistant to just about every threat Nature could throw at it: deer, insects diseases, cold, drought. And it’s a native plant, but native throughout the midwest, not here. Should I call it a “native?”
Black locust is such a useful tree that its spread was aided and abetted by humans. But it also would have spread, albeit more slowly, without our intervention. Even autumn olive, given enough time, might have hitch-hiked here in some way from Asia.
The Earth’s landscape is not static. Changes represent interactions of climate, vectors, chance, and time. Nostalgia may have us wishing for the view out the window to remain the same as it was when we were children, but that’s not Mother Nature’s way.
Playing Around With Stems
Top Doggery
Within any plant a push and pull goes on between fruiting an stem growth. Both require energy, which the plant has to apportion between the two. The more vigorously growing a stem, the less fruitful it is.
All this talk of hormones and inherent stem vigor is more than academic; it can translate into delicious fruits.
Tied branches in British orchard
But pear trees, especially in the youth, tend to put too much of their energies, too much for me, at least, into stem growth. The result is that they can take long time to settle down and begin bearing fruit.
Hence, the strings. I can change my pear trees’ habits by merely tying down branches, reducing the effect of that auxin so that growth is more uniform along a length of the stem. And, as important, slowing growth nudges the energy balance in the direction of fruiting.
More Fruit or More Growth?
Branch bending is not only for coaxing a tree into fruiting. On young branches, it creates a wide angle between a branch and the developing trunk. Wide angles here have been shown to result in good anchorage, sturdy side branches that can carry a weight of fruit.
Suppressing the vigor of side branches also ensures that they won’t compete with the developing trunk, which needs to be top dog.
And using string to play around with plant hormones isn’t needed on every fruit tree. At the other extreme from pear in its growth and fruiting habits is peach. Peach is naturally very fecund, and becomes naturally so at a very young age.
Beauty, Fruit, and Fun
All this concern with auxin, vigor, and fruiting comes most prominently into play with espalier, which is the training of a tree to an orderly, often two dimensional form. The tracery of the branches themselves adds to the decorative value of the plant.
Fruiting espaliers, besides being decorative, produce very high quality fruit. Pruning and branch bending maintain a careful balance between yield and stem growth, and the form of the plant allows leaves and fruits to bathe in sunlight and air.
