Pests – Lee Reich

FOR THAT UNWELCOME MEDITERRANEAN LOOK

July 11, 2023/4 Comments/in Pests/by Lee Reich

One Name for Many Diseases

The powdery white coating I notice on leaves of my peony and lilac plants gives them a very Mediterranean look. Not attractive, though, at least to me, because that’s a sign of a disease, appropriately called powdery mildew. If I look around the garden, the disease is probably showing itself, or soon to do so, on a wide variety of plants, including phlox, zinnia, squash, gooseberry, and many more. (This blog post is excerpted from the chapter about plant stresses in my book The Ever Curious Gardener: Using a Little Natural Science for a Much Better Garden.) Even though powdery mildew is pretty reliable in showing up each season on certain plants — this is important! — the disease doesn’t necessarily spread from one kind of susceptible plant to the next. Many different fungi are responsible for the disease we collectively call powdery mildew, and each of these fungi have specific plant hosts. Thus, the fungus that causes powdery mildew on lilac (the fungus is Microsphaera alni) cannot cause powdery mildew on rose (caused by the fungus Sphaerotheca pannosa). Read more

PESKY CREATURES

May 17, 2023/4 Comments/in Pests/by Lee Reich

Vegetables are Easy, But . . .

I consider vegetables generally easy to grow, especially if you grow lots of different kinds. If one kind does poorly one year, there are lots of other vegetables in the garden doing well, and there are other years.

Still, vegetable — and flower — transplants are especially apt to suffer attacks from three pests this time of year, each leaving a telltale clue to its presence or handiwork. Stems might be chopped off at the soil line. Leaves might be chewed. Or leaves might be shot full of tiny holes. The culprits? Respectively: cutworms, slugs, and flea beetles.

All three culprits have cosmopolitan tastes, attacking practically any transplant you set out. Fortunately, these pests can be controlled to some degree without toxic (to you, and nontarget creatures) sprays, usually without resort to any sprays.

A Few, But Deadly, Bites

Cutworms take only a few bites out of new transplants, which would not be reprehensible if those few bites were not at ground level. Seedlings topple and, because they are just seedlings, never recover. The damage should not be confused with damping-off disease, which is a fungus that also attacks at the soil line, but only afflicts newly emerged seedlings. To make sure, scratch with your finger in the soil near the toppled plant and look for the bugger. Then squish it.

Cutworms are easily repulsed with some sort of barrier, such as a cardboard collar around each plant. Toilet paper tubes cut a couple of inches long are convenient for this purpose. Surround each transplant and press the collar a half-inch or so into the soil.

Before a cutworm takes a bite of a plant, it wraps its body around the plant’s stem to make sure the stem is tender enough to bite into. Once stems of vegetable and flower transplants toughen, cutworms leave them alone.

I used to fool cutworms by sticking one toothpick in the ground right up against each of my transplants. It worked. The insects think they are embracing small, woody-stemmed trees and leave the young plants alone.

Another method to foil cutworms (which I have not tried) is to trap them in foot-deep holes, made with a broom handle or an inch-thick dowel. As daylight approaches, the cutworms climb into these holes for shelter. What the cutworms do not realize is that they are incapable of ever climbing back out.

The life of the cutworm is not easy: this pest is also food for birds and ground beetles, and is parasitized by certain small wasps.

I have to admit that I haven’t used any of these cutworm control methods for years and years. I never see cutworms or their damage anymore. I’d like to think that it’s evidence of my having a green thumb, but much more likely are the robins and morning doves that I see patrolling my garden early every morning.

Slimy Slitherers

Moving on to slugs . . . these creatures love wet weather. Slugs slither around at night and by morning their presence is made known by the shiny trails and ragged leaves they have left. Here in the Northeast, they are up to a couple of inches long. In other parts of the country, they get as large as a half a foot or more long.

Slugs don’t like anything sharp or caustic rubbing against their slimy bodies, so if you sprinkle a circle of sharp sand, diatomaceous earth, or woodashes around your plants, a slug will think twice before crossing this barrier. Unfortunately, these barriers must be renewed after rains, which is when slugs are most active.

You could take a flashlight into the garden at night and sneak up on slugs while they are at work. They are slippery to handpick, so take along a saltshaker. Sprinkling salt on them will kill them. It’s gruesome to watch, but very effective.

Beer is a somewhat effective poison bait for slugs. Put some beer — Budweiser is one of the best — in a shallow pan or cqn and sink it into the ground so the lip is about one inch above ground level. Almost immediately slugs will start inching to their demise.

A bait containing iron phosphate is very effective agains slugs, and considered nontoxic to just about everything else, including humans.

No need to open a fresh bottle each night, for slugs are happy even with stale beer. Some gardeners report good results with only yeast plus water. You might need lots of traps because slugs won’t “hear” the siren song of beer beyond a few feet.

A Different Kind of “Flea”

Flea beetles, which perforate leaves with small holes, are the most difficult of the three pests to control without pesticides. You may not notice the beetles because they’re only a couple of millimeters long and hop away when approached. Fleabeetles on eggplant

Lawrence D. Hills, in his 1974 book Grow Your Own Fruit and Vegetables, describes a contraption he put together himself. It looks like a high-riding skateboard, with a long handle at the top of the middle and a horizontal metal wire down across the front of the board. He tacked flypaper on the underside of the board. (Tangletrap© spread on the underside would work as well, or better.) As you push this contraption over a row of plants, the wire disturbs each leaf — and the flea beetles. Flea beetles hop away when disturbed; for these flea beetles, it’s their final hop as they get stuck on the flypaper.

Predatory nematodes, which you can purchase, might also limit flea beetle damage by attacking eggs in the soil. I added predatory nematodes that have the potential to perennialize to my soil, available from the Shields Lab at Cornell University. These have been shown to be effective against some pests that spend part of their lives in the ground. Patience is needed as their numbers multiply.

Flea beetles are especially fond of cabbage and its kin, as well as spinach, beets, and potatoes. They’re mostly a problem on my eggplants; actually, just about everybody’s eggplants. I and many other gardeners and farmers thwart them, by covering plants with a barrier of a “floating row cover.” These lightweight materials, made from spunbonded or woven synthetic materials, are permeable to water, air, and sun, but impermeable to insects. The barrier must be in place before seedlings emerge or right after setting out transplants.

Sometimes it’s appropriate just to ignore pest damage, for awhile, at least. Small transplants often outgrow flea beetle or slug damage, provided the plants are growing rapidly enough and the pests are not too many or too hungry.

MORE OF MY FAVORITE TH . . . GRAPE VARIETIES

September 21, 2022/1 Comment/in Pests/by Lee Reich

The Birds and the B . . . Vespids

Hot and dry. What great summer weather it’s been here for grapes. Most years around this date, I’d go out every morning and pick bunches for fresh eating, continuing to do so for weeks to come. Basket of grapes

Alas, where there are grapes, you’ll find the birds and the be. . . vespids (the family of wasps and hornets, not bees). No raccoons or foxes, here on my grapes, at least. Here you’ll also find paper bags stapled around about a hundred bunches.

The bags are meant to protect the enclosed bunches from birds and insects. This year was a first: Thirsty birds pecked holes in the bags through which they could reach, then peck at the grapes hanging within. By my estimate, about three-quarters of the bagged bunches suffered damage or were finished off in toto.

In addition to the damage inflicted by the birds, the resulting holey bags provide easy entrance to wasps and hornets, who further tear up the bag and finish off the fruit repast started by birds.

COMPOST TEA REVEALED

August 24, 2022/3 Comments/in Pests, Soil/by Lee Reich

First Step, Identification

A few years ago I went to a nearby permaculture convergence. (Actually a “permaculture conference; those people have the best terms for what they do). I’ve grown plants in what I learned was a permie way for many decades, so I’ve been accused of being a permaculturalist. I was even invited to do a presentation and host a farmden tour for the convergence.

While there, I had the opportunity to attend a lecture by someone who has been billed as the diva of dirt, or, at least, of compost tea, specifically aerated compost tea (ACT), Dr. Elaine Ingham. You’ve never heard of ACT!? It became the hot, new thing years ago, perhaps still is, as an alleged cure for poor soil and plant pests. I’d been skeptical and thought that hearing and speaking to Dr. Ingham in person could entice me into the fold. Making compost tea

Dr. Ingham showed myriad images of fungi, nematodes, and other creatures that you might find in compost piles and teas. We saw many “bad guys” that lurk in poorly aerated composts and teas. The “bad guys” are bad, she asserted, because they release toxins into the soil and puff away valuable nitrogen, sulfur, and phosphorus in various forms as gases.

Dr. Ingham suggested monitoring our compost piles and tea happenings by purchasing a microscope and, with the help of her workshops, identifying resident microorganisms. Hmmm; interesting, but is it really necessary for a green thumb?

While the panoply of microorganisms discussed was impressive, I contend that even a well-aerated compost pile or tea is bound to have some poorly aerated pockets. It’s not a “bad guys” vs. “good guys” situation, but a question of generally favoring an excess of “good guys.” Also, once compost is spread on the ground, the large surface area presented is going to tip the balance even more in favor of aerobic conditions.

To identify what organisms are in a compost pile, you have to get them out of the pile and onto a microscope slide. Easy. Just soak some compost in water and strain it. Or use a compost teabag. But wait! Is that really the spectrum of microorganisms that call that compost home? Not necessarily. What are staring up at you from that microscope slide are creatures that can be leached most readily into water. What you see also might depend on how long you steeped the teabag and who can squeeze out into the water through whatever size holes are offered by the strainer or the teabag.

Will Compost Microbes be Happy Far from their Compost Home? More fundamentally, I question basic assumptions underlying the use of compost tea. Even if you have beneficial organisms in hand (figuratively) and sprinkle them on the ground, they’re bound to expire unless the environment is suitable. Microorganisms in the tea might have enjoyed life within the dark, moist innards of a compost pile; the soil environment ain’t nothin’ like home for them.

Spraying ACT or any compost tea on plant leaves should likewise have little or no effect on plant diseases; again, conditions on a leaf surface aren’t conducive to their survival. In the evolutionary scheme of things, why would a microorganism that thrives in the dark, moist, nutrient-rich innards of a compost pile survive on the sunny, dry, nutrient-poor surface of a plant leaf, let alone provide any benefits? Spraying plants

Over the last few decades, people have spritzed plants and sprinkled soils with compost tea, looking for effects such as improved soil structure or drainage or increased plant resistance to pests. Independent well-designed, vetted studies do not generally support claims made for compost tea.

True, there are some studies that show some benefits. I contend that if you spray just about anything on a plant leaf and have enough plants in the study along with sufficiently detailed measurements, some statistically significant effect might be noted. But every statistically significant effect isn’t also biologically significant. And looking over a number of studies, some few show a benefit from compost tea, many demonstrate no effect, and for a number of them, the effect of compost tea is detrimental.

Soluble nutrients do leach out of a compost teabag into water. The resulting compost tea, then, becomes a liquid feed for plants, effective either poured on the ground or even sprayed on leaves. So there can be some benefit from compost tea, a nutrient effect, not a microbial one.

Bulk is Good

Except in special situations, soil environments naturally host microorganisms that thrive best in them. A similar situation exists with earthworms. Years ago, perhaps still, advertisements in the back pages of gardening magazines would offer earthworms for sale. The reasoning went that good soils are teeming with earthworms, so purchasing and importing these creatures to you garden will make your soil better. Not true. The earthworms will die out if conditions and food are not to their liking. The same goes for microorganisms.

(An example of an exception to what I wrote in the previous paragraph is a study that was done in Puerto Rico back in 1950. THE USDA was trying, with little success to introduce a more useful, but non-native pine, to the island territory. Mycorrhizae are fungal symbionts that infect practically all plants; the fungus gets some foods manufactured by the plant in return for moving more nutrients and water to the plant for improved growth. The appropriate fungal symbiont was lacking in Puerto Rican soils. After inoculating plants with an appropriate fungus, the inoculated, introduced pines grew six times more than their introduced brethren that had not been inoculated.) Compost being shovelled

Except in rare situations, as in the example above, earthworms, microorganisms, and other creatures generally inhabit environments most congenial to their flourishing. Perhaps not enough of them, and what they really need is food to give their populations a boost, and food means some form of organic material. That is, bulky organic materials, such as compost, manure, leaves, and straw.

Good gardening comes form using a pitchfork, not an elixir. Does anybody still make and use compost tea?

A BACTERIA TO THE RESCUE

July 28, 2022/6 Comments/in Pests/by Lee Reich

A Cabbageworm is a Cabbageworm is a . . . Not!

A few weeks ago, one or more of the few species of “cabbageworms” began munching the leaves of my cabbage and Brussels sprouts plants. They ignored kale leaves, thankfully, because it’s my favorite of the three.

Cabbageworm damage

A laissez fair approach would have left the cabbages and Brussels sprouts mere skeletons, so I had to take some sort of action.

For the record, “cabbageworms” are actually not worms, but a few species of caterpillars all classified — and this is important — in the order Lepidoptera. Here’s the lineup: A cabbage looper arches its back when moving, and is light green with a pale white stripe along each of its sides and two thin white stripes down its back.

Cabbage looper

A diamondback moth larvae is 5/16 inch long, yellowish-green, and spindle shaped with a forked tail.

Diamondback moth larva

A cabbageworm (yes, one kind of cabbageworm is named “cabbageworm”) is one-and-a-quarter inches long, velvety green, and has a narrow, light yellow stripe down the middle of its back.

Cabbageworm & cross-striped cabbageworm

A cross-striped cabbageworm is 3/4 inch long and bluish-gray in color with many black stripes running cross-wise on its back, below which a black and yellow stripe runs along the length of its body.

Natural Control

I put an end to whichever “worms” were the culprits, and was able to do so without resorting to any chemical spray, by spraying the plants with Bt. Bt is the commonly used abbreviation for Bacillus thuringiensis, a bacterium that causes disease in certain insects. After ingesting Bt, a cabbageworm becomes sick, stops eating, and dies. Since the Bt I sprayed is toxic only to lepidopterous insects, it doesn’t pose any danger to other creatures, such as birds, cats, dogs, humans, and even other insects.

The insecticidal properties of Bt have been known since early in the twentieth century, when the bacterium was discovered as a silkworm pest by Japanese researchers. (Silkworms are also Lepidoptera.) The originally discovered strain of this bacteria is toxic only to caterpillars, which are larvae of butterflies and moths, and was first used purposefully to control the European corn borer in Europe in the 1930s. Interest in Bt waned in the late 1940s, when nerve gases used during World War II led to the development of new types of chemical pesticides. In the 1960s, agricultural scientists finally began to take a second look at Bt.

Many strains of Bt have been isolated. The ones for cabbageworms and other Lepidoptera are Bt aizawai and Bt kurstaki. Thuricide label The strain Bt var. israelensis is toxic to larvae of black flies and mosquitoes. Another strain, Bt var. san diego, is toxic to Colorado potato beetle larvae.

All these strains of Bt are available commercially. The bacteria are packaged in a dormant condition either as a dry powder, a liquid suspension, or, in the case of Bt var. israelensis, a slow release ring that is floated on water to kill mosquito larvae. Bt goes under a number of brand names which don’t give a hint of the pesticide’s ingredients, so read the label to make sure of what you are buying. The product I use goes under the trade name Thuricide.

Bt is a living organism, so I store it in such a way as to prolong its viability. (Here on the farmden, Bt resides in the back of the refrigerator, which is generally a strong no-no for pesticides. (But Bt is nontoxic, and there are no children in the house.) Kept cool and dry, the bacteria will remain viable in its container for two or three years. Bt works quickly enough so I can check for discolored, blackened, or shriveled larvae the next day to see if the spray is still viable.

But . . .

Is there some trade-off that must be made when using this apparently benign pesticide? Yes, insect pests can develop resistance to Bt, just as they do to chemical pesticides. Resistance is most likely from continuous, repetitive use of any single pesticide, or different ones with the same mode of action.

This problem, with Bt, has been exacerbated since almost 500 million acres of crops, mostly field corn and cotton, have been genetically engineered with insecticidal Bt genes. It’s equivalent to the field being constantly sprayed with Bt. Some resistance has been found.

In my garden, I apply Bt at the recommended rate, only to afflicted plants, and only when a pest problem gets sufficiently out of hand to warrant treatment.

There’s another good reason for careful use of at least the original strain of Bt. Since this strain is toxic to caterpillars, indiscriminate use could substantially decrease the caterpillar population and, hence, the numbers of moths and butterflies. My distaste for the celeryworm, which has a voracious appetite for carrot, celery, and parsley leaves, is tempered by the beauty of its adult form.

Celeryworm

Surely the elegance and grace of the adult form, the black swallowtail butterfly fluttering about the garden, adds as much beauty as a marigold or rose.

Black swallowtail

HEAT? DROUGHT? NO PROBLEM.

July 20, 2022/6 Comments/in Gardening, Pests/by Lee Reich

Physiological Workaround

Portulaca is a genus that gives us a vegetable, a weed, and a flower. All flourish undaunted by heat or drought, a comforting thought as I drag the hose or lug a watering can around to keep beebalm, an Edelweiss grapevine, and some marigolds and zinnias — all planted within the last couple of weeks — alive.

Portulaca employ a special trick for dealing with hot, dry weather, which presents most plants with a conundrum. On the one hand, should a plant open the pores of its leaves to let water escape to cool the plant, as well as take in carbon dioxide which, along with sunlight, is needed for photosynthesis. On the other hand, the soil might not be sufficiently moist or the pores might end up jettisoning water faster than roots can drink it in, in which case closing the pores would be the ticket.

Portulaca gets around this conundrum by working the night shift, opening its pores only in darkness, when little water is lost, and latching onto carbon dioxide at night by incorporating it into malic acid, which is stored until the next day. Come daylight, the pores close up, conserving water, and malic acid comes apart to release carbon dioxide within the plant. I describe this specialized type of metabolism in my book The Ever Curious Gardener: Using a Little Natural Science for a Much Better Garden.

From the Pampas to my Garden

Let’s start with the flower Portulaca, P. grandiflora, which goes either by a common name that is the same as the generic name, or by the name “moss rose.” In truth, the plant is neither a moss nor a rose. But the tufts of lanceolate leaves do bear some resemblance to moss, a very large moss. And portulaca’s flowers, which are an inch across, with single or double rows of petals in colors from white to yellow to rose, scarlet, and deep red, are definitely rose-like. The plant grows to a half-foot-wide mound, with stems that are just barely able to pull themselves up off the ground under the weight of their fleshy leaves. Moss rose

Moss rose is native to sunny, dry foothills that rise up along the western boundary of the South American pampas. As might be inferred from its native habitat, this plant not only tolerates, but absolutely requires, full sun and well-drained soil. Such requirements, and low stature, make the plant ideal for dry rock gardens and for edging.

Moss rose is easy to grow from seeds sown at their final home, or started in flats for transplanting. Some gardeners mix the extremely fine seed with dry sand before sowing, to ensure uniform distribution.

Once blossoming begins, it continues nonstop until plants are snuffed out by frost. Moss rose is an annual, but sometimes will seed itself the next season. However, double varieties (plants with double rows of petals) grown this year will self-seed single varieties (plants with a row of petals) “volunteers” next year.

Plant It or Not, It Will Be There

The vegetable and the weedy Portulaca can be dealt with together; they are one and the same plant, P. oleracea. Somewhere in your garden now, you surely have this plant, whose succulent, reddish stems and succulent, spoon-shaped leaves hug the ground and creep outward in an ever-enlarging circle.

The common name is purslane, though it has many aliases, including pussley, Indian cress, and the descriptive Malawi moniker of “the buttocks of the wife of a chief.”

Tenacity to life and fecundity accord purslane weed status. Pull out a plant and toss it on the ground, and it will retain turgidity long enough to re-root. Chop the stems with a hoe, and each piece will take root. Even without roots, the inconspicuous flowers stay alive long enough to make and spread seeds.

My one consolation with having this weed in my garden is that it’s easy to remove, robs little nutrients or water from surrounding plants, and, being low-growing, casts little or no shade. Perhaps it even protects the soil surface from sun beating down on it or pounding raindrops from washing away soil. On the other hand, left unattended, it could take over a garden this time of year.

You Could Eat It

What about purslane, the vegetable? Take a bite. The young stems and leaves are tender and juicy, with a slight, yet refreshing, tartness. Purslane is delicious (to some people, admittedly not to me) raw or cooked, and is much appreciated as a vegetable in many places around the world besides its native India.

I have actually tasted the result of the plant’s specialized metabolism in summer by nibbling a leaf of purslane at night and then another one in the afternoon. Malic acid makes the night-harvested purslane more tart than the one harvested in daylight.

There are cultivated varieties of purslane for planting(!) in the vegetable garden. These varieties have yellowish leaves and a more upright growth habit than the wild forms. Wild or cultivated, the plants can be grown from seed or, of course, by rooting cuttings from established plants.

As far as actually planting purslane in my garden, I agree with the view of another garden writer who said “it is a reckless gardener who would plant purslane.” That does not mean that I do not grow purslane, though, for plenty keeps appearing despite my weeding.

Every once in a while, I again try eating it. I have enjoyed it in salads in restaurants to such accompaniments (or taste and texture disguisers) as feta cheese, olive oil, vinegar, and other strong flavors.

If you do opt to plant purslane, you must replant it yearly. Like the moss rose, purslane is an annual plant. Once established in the spring, both purslane and moss rose need no further care. Now, if only moss rose were a bit more weedy . . .

And Never the Twains Shall Meet

December 8, 2021/15 Comments/in Flowers, Fruit, Pests/by Lee Reich

Detente, Plant Style

“Oh, East is East, and West is West, and never the twain shall meet,” wrote Kipling a hundred years ago. Not so with respect to gardening. The Far East, spared the great sheets of ice that descended upon North America during the Ice Ages, has been a treasure trove of plants. Though distance, water, and culture kept the gardening worlds of the East and the West separate for millennia, the gap began to narrow just over two-hundred years ago.

The first plants to trickle out of China were those plants most accessible to foreigners — cultivated plants growing at and around seaport towns. It was not until the

Potted kumquat

middle of the nineteenth century that plant explorers pressed inland to open wide the treasure chest of wild and cultivated plants, many of which have found their way into my garden. These plant explorers are honored in plants that bear their names. Fortunella, or kumquats (the genus was changed recently, with kumquats now in Citrus), named for Robert Fortune. I grew kumquats, wintering them indoors at a sunny window, for many years. Citrus meyerei, the Meyer lemon, named for Frank Meyer; my two Meyer lemon plants, also at sunny windows, are just beginning to send out new shoots, soon, with flowers.

(There is a darker side to “East meets West.” Up until the middle of the 19th century, Japan was isolationist, which was not to the liking of U.S. commercial interests. President Millard Fillmore enlisted “Admiral” Matthew Perry to force his boats into Japan’s Edo Bay to intimidate the Japanese into opening their ports to American trade, as well as other concessions. This gunboat diplomacy was successful.)

Meyer lemon in bloom

Trans-Pacific Cousins

From the Far East came plants for which we had no counterparts, plants such as the gingko tree. There also came plants more, or at least equally, valuable as related plants found here. We have our redcedar (Juniperus virginiana); from China comes Chinese juniper (J. chinensis). Our redcedars turn drab brown in winter, but the Chinese species remain lush green throughout the year.

Common witchhazel (Hamemalis virginiana) and vernal witchhazel (H. vernalis) are understory shrubs of American forests; Asian forests likewise have two witchhazel

Arnold’s Promise witchhazel, today

species: Chinese (H. mollis) and the Japanese (H. japonica). The Asian species blossom at different times than the American species, so are useful for extending the period of witchhazel bloom. My Arnold’s Promise variety of witchhazel, a hybrid of the Chinese and the Japanese species, is in bloom right now although blooms often wait until midwinter to open

Where East really does meet West in gardening is in hybrids of Eastern and Western species. The hybrid tea rose, common in American gardens from New England to the Southwest, is one example. “Tea” in the name traces back to a tea-scented rose (Rosa gigantea) from China. For centuries, the Chinese hybridized this summer-flowering climber having huge, yellow flowers with a dwarf form of another species, R. chinensis. In the nineteenth century these hybrids were further hybridized with European roses to make hybrid tea roses.

Pest Control

American plant breeders sometimes have had to look across the Pacific to find plants with resistance to a disease originally brought to America from the East. Chestnut blight turned up at New York’s Bronx Zoo in 1906, and within fifty years, the tops of American chestnuts (Castanea dentata) were dead or dying in seven million acres of Appalachian forests. The roots, which are not affected by the blight, keep sprouting new shoots, which then die after a few years, but keep the blight fungus “fed.”

Blight on chestnut bark

Japanese chestnut (C. crenata) and Chinese chestnut (C. mollisima) evolved with the blight and show some resistance to it, so have been hybridized with the American species to produce blight-resistant trees, such as the variety Sleeping Giant. These trees lack the grandeur of the American chestnut, but they do make larger nuts. My chestnuts, the varieties Colossal, Marigoule, and Precoce Marigoule, are hybrids of European chestnut (C. sativa) and Japanese chestnut. They’re all blight resistant, but resistance is a matter of degree. My Colossal is finally succumbing to blight.

Dutch elm disease entered America via Europe, but entered Europe from Asia, probably about the time of World War I. Once again, Asian elm species — Chinese elm (Ulmus parviflora) and Siberian elm (U. pumila) — are resistant to the disease. Hybridization has produced such disease-resistant varieties as Patriot and Accolade.

Plants of Asia even have been useful in providing resistance to diseases not originating in Asia. Fireblight disease of pears was first noted in New York’s Hudson Valley at the end of the eighteenth century. Some Asian pear species are resistant to fireblight. Over a hundred years ago, hybrids between Asian and European pears that showed some resistance to blight were produced, at first by accident. These original hybrids did not taste very good, but did make pear-growing possible in blight-prone southeastern U.S.

The story isn’t yet over. Expeditions still return from such areas as remote villages and forest of China and the Himalayas to yield “new” plant treasures.

A BRIGHT FUTURE

May 27, 2021/15 Comments/in Fruit, Pests/by Lee Reich

As Good As It Gets

You might think that writing about good weather would tempt the fates. I’ll thumb my nose at the fates and go ahead and write that this spring is the best spring, gardenwise, ever in all the decades since I’ve been gardening. The flowers have been more vibrant with color and, it seems, also in greater profusion. The air has been particularly fragrant, especially now with the intoxicating aroma of black locust blooms following closely on the heels of autumn olive’s sweet scent.
Apple tree in bloom
My fruit trees are most thankful for this spring’s beneficence. In all the years of growing fruit here on the farmden, never has the landscape been so brightened by snowballs of white blooms of plum and pear trees, pinkish blossoms of apples, and peaches’ pure pink blossoms.
Apple blossoms
Peach blossoms
The now-fallen petals are no cause for wistfulness, because those clusters of flowers have now morphed into clusters of fruits

Why this Year?

What makes for such a glorious spring? The weather, of course, both this spring’s in addition to last winter’s and even last spring’s. Let’s first go back to last spring’s weather effects.

During spring 2020 the weather warmed going into April, coaxing flower buds on fruit trees to swell. Then, towards the end of that month and into May, a number of nights saw temperatures that nipped life from many flowers, then open, especially the 22° temperature on April 23rd and then subfreezing temperatures on May 9th, 13th, and 14th. (All this information handily recorded and passed onto my computer via Sensorpush sensors I have at two locations outdoors and one location in the greenhouse.)
Peach fruitlets
Prelude to the present season began with a relatively mild winter, for which peach flower buds, which suffer damage at around minus 15°, were especially appreciative. And this spring has seen more or less gradually warming temperatures with — and this is most important — no late, damaging frosts. Buds for a current spring’s blossoms develop the summer of the previous year. Seeds in developing fruits produce a hormone that suppresses flower bud formation, so a heavy crop one year means a lighter crop the following year, and vice versa, all other things being equal. Last year’s late frosts knocked out much of the potential fruit crop so this year the trees did what they do, compensating for last year’s loss with more blooms.
Asian pear espalier
Fruit trees can afford to lose a certain number of flowers to cold each year. For instance, each flower bud of an apple tree unfolds to five flowers, and only 5 percent of those flowers need to set fruit for a full crop of apples. Furthermore, a temperature below 32° doesn’t always cause damage; just how much damage ensues depends on the the growth stage of flower buds and how cold it gets. Using apples, again, as an example, when their buds have expanded just enough to hint at the five flowers within (the “tight cluster” stage), 27° will kill 10 percent of them, 21° will kill 90 percent of them. More details for apples and other fruits can be found here.

Another variable is that temperatures can vary a little at various points within a tree, which can be important at these critical temperatures.

Not Yet Home Free

This auspicious spring is not a call for me to just sit back and wait for the delicious bounty to hang on the branches awaiting my picking. My work is cut out for me.

One job, to begin soon, will be thinning the fruit, that is, removing lots of them. In addition to upping the chances for a good return bloom and harvest next year (remember the seeds and the hormones), fruit thinning lets the trees channel more of their energy resources into fewer fruits. The result: Fruits that remain are larger and more flavorful. Fruit thinning also lessens the chance of limbs breaking under the the load of too many fruits, and lessens pest problems. Two apples touching each other provide good cover for the larvae of codling moths to burrow into the fruits to become the classic “worm in the apple.”

Apple fruitlets Commercially, tree fruits are thinned with chemical sprays but I’ll be thinning by hand. The plan is to reduce the number of fruits to one per bud, leaving the largest and most pest-free, and allowing remaining fruits to sit no closer than about a half a foot apart along branches. Larger kinds of fruits are the ones that need thinning, which is nice because it would be very tedious to thin small fruits, such as cherries. Winter pruning removes some branches with fruit buds, so also contributes to reducing the load, as does trees’ natural shedding of some excess fruits.
Pear fruitlets
Another job, which began a few weeks ago, is keeping an eye out for and protecting fruits from insects and diseases — particularly problematic on a less than perfect site such as here on the farmden. All of the common tree fruits, except for pear, are very prone to these problems throughout much of eastern North America.

On a backyard scale, the problems are few but serious, in some cases serious enough to eliminate almost the whole crop or render it inedible. The major culprits are plum curculio, codling moth, apple maggot, oriental fruit moth, brown rot, apple scab, fire blight, and cedar apple rust. Not to mention deer and squirrels.

My tack is to take a multi-pronged approach, with some spraying (mostly organic), nurturing the soil (lots of mulch and compost) and the plants (pruning and fruit thinning), fostering beneficial insects with plantings that encourage their presence and with careful choice and limited amount of sprays, trapping pests (hanging fake apples, Red Delicious, with sticky Tanglefoot in trees), and possibly bagging individual fruits. See Grow Fruit Naturally for more about these approaches.

Even if there is “many a slip ‘twixt the cup and the lip,” every fruit grower has to be an optimist.

Plant Sale Reminder

This is the last week of my annual plant sale. For more information, go to https://leereich.com/2021/05/last-week-of-2021-plant-sale.html

And, A Free Webinar, “Weedless Gardening”

For more information, go to www.leereich.com/workshops.

PEST PLANS

March 10, 2021/4 Comments/in Pests, Vegetables/by Lee Reich

My Sweet, Corn

Spring is here this week, weatherwise, at least. Not to bring back bad memories, but with real spring just around the corner, now is a good time to revisit two or three of last year’s worst pest problems, and plan some sort of counteraction. Not that those memories are really that bad; the interaction of pests, plants, the environment, and my hopefully green thumb is always interesting.

Golden Bantam sweet corn, non-hybrid The most serious pest problem last year, most serious because it affected one of my favorite vegetables, was a disease that devastated my later plantings of corn. Looking at the symptoms — yellow streaks on leaves that turned to tan, dead areas — my diagnosis was the bacterial disease, Stewart’s wilt. Some plant pathologists pointed out that Stewart’s wilt is very rare around here, and that the problem was probably the fungal disease, northern corn leaf blight.

Disease development on leaves

I’m not 100% convinced it’s the blight but, more important is what to do in either case. I like my sweet corn. (Popcorn and polenta corn were unaffected.) Stewart’s wilt can be avoided by growing resistant varieties. But not only do I like my sweet corn; I like specifically Golden Bantam sweet corn.

A hundred years ago, Golden Bantam corn was bred into a number of hybrid varieties, some of which are resistant to Stewart’s wilt. Golden Cross Bantam, for example. As I said, though, I like my Golden Bantam. I’ve grown Golden Cross Bantam and its flavor fell short of Golden Bantam.

Northern Corn Leaf Blight

As a nonhybrid variety, Golden Bantam turns up in a number of strains. My seed came from a few sources, and it’s possible that some strains are more resistant than others. My two earlier ripening beds had no disease. Last year I didn’t keep records of which beds got seed from which sources. This year I’ll record it.

Northern corn leaf blight can also be controlled with resistant varieties. As I wrote, though, Golden Bantam is the variety for me, so other varieties are not an option, for now at least.

Plus, there are other options for dealing with northern corn leaf blight. Thorough cleanup at season’s end removes spores that would overwinter. Done. Not planting corn in the same bed for one to two years to starve out the disease. Done. Good air circulation and humidity control by keeping weeds in check. Not so done each year. Colder, damper air descends readily into the Wallkilll River Valley here and, while weeds are under control, I do a lot of interplanting, which has the same effect, humidity-wise, as weeds.

Who knows? Another season, different conditions. The problem, whichever it is, never showed up before; perhaps it won’t ever again.

An Unwelcome Newcomer

The other significant pest problems last year were with my onions and leeks. As usual, I started onions from seed indoors in February and planted them out in early May. Another batch got direct seeded right out in the garden in April. Both plantings — I’m ashamed to admit — yielded stunted bulbs, many no bigger than a nickel. Leeks likewise were stunted, or deformed.

Also embarrassing is that I didn’t take the trouble to examine the plants closely for clues. This would have been relatively easy since the probable culprits were leek moth or thrips, both now common, around here, at least. Plus, I’ve previously had a problem with leek moth.

Leek moth, a European native, is a relative newcomer on this side of the Atlantic, first showing up in northern New York state in 2009. Temperatures above 50°F in late winter awaken papae or adults overwintering in debris, and Ms. Leek Moth soon starts laying eggs, lots of them. In less than a month, new adults start feeding on leaves. Subsequent generations follow suit, feeding on leaves, weakening the plant, and also the parts — stalks and bulbs — that we want to eat.
Leek moth damage
Early signs of impending damage are the eggs, tiny and transluscent and laid on the undersides of the leaves. Or, later, the caterpillars, slender, yellow and also small, less than one-half inch long. The important thing is to take action at the first signs of damage — holes in leaves and caterpillars. To see the caterpillars, leaves of garlic and leeks need to be unfolded; hollow leaves of onions need to be opened for an inside look.

Leek moth damage, later

Preemptive action would be to use a lightweight floating row cover beginning early in the season to keep Ms. Leek Moth from laying eggs on plants.

Once damage or caterpillars is found, spraying, my least favorite garden activity, is needed. Organic sprays include Pyganic, which is effective for a couple of days, or, more lasting, Entrust, a natural substance made by a soil bacterium. In either case sprays need to be applied strictly according to label directions, both for effectiveness and for legality

Thrip, Thrip, Thrip – No, Not a Frog

Thrips, the other possible, or additional, culprits are very small, but their damage is telling: silver lines and/or small white patches on leaves and tip dieback. To see the culprits themselves, you’ve got to look closely between the leaf folds, zeroing in on the youngest leaves, for light yellow nymphs and darker adults. Hot, dry weather suits them best, which were the conditions here last summer.

Thrip damage

Because thrips overwinter in debris, thorough cleanup helps. Straw mulch has potential, although one study showed that while it reduced the number of thrips, it didn’t affect yield. It did increase the number of jumbo onions, though. Go figure.

Certain kinds of onions are more resistant to thrips than others. In general, red onions (which I anyway don’t grow) are very susceptible, yellow ones (which I do grow) less so, and Sweet Spanish onions (which I have grown in the past) are relatively resistant. I’ll no longer grow the variety Candy, which is listed as susceptible.

Certain plants, on which thrips do little damage, can draw thrips away from the onions. Carrots, tomatoes, cabbage and its kin, carnations, and chrysanthemums, as examples.

And, of course, there are organic sprays, a last resort for me. Beauvaria, a naturally-occuring insect killer, for one. Also the relatively benign insecticidal soap paired with Neem. And again, Entrust.

As I said, I’m not bemoaning these insect and disease pests. It’s reassuring for me to stop and think how few or no pest problems vegetables typically affect my kale, tomatoes, peppers, okra, and most other vegetables grow. They all grow well with little more than yearly additions of compost to the beds, and timely planting and watering.

Prune Fearlessly

A reminder that I’ll be holding a FEARLESS PRUNING webinar on March 29, 2021 from 7-8:30pm EST. This webinar will take the mystery out of pruning, so that you can prune your lilac and rose bushes, apple trees, blueberry shrubs — all trees and shrubs, in fact — to look their best and be in vibrant health. Fearlessly. For more information and to register, go to www.leereich.com/workshops.

TELLING SNOW

February 10, 2021/20 Comments/in Gardening, Pests, Pruning/by Lee Reich

I Grow Taller

“Make hay while the sun shines” is fine advice in its season. For winter, how about? “Prune while the snow is high and firm.”

My apple and pear trees are semi-dwarf, presently ranging from seven to eleven feet tall. Even though I have a pole pruner and various long-reach pruning tools, I still carry my three-legged orchard ladder out to the trees with me to work on their upper branches. Sometimes you have to get your eyes and arms and hands right up near where you’re actually cutting.
Pruning on snow
A few years ago, as I was looking out the window and admiring the foot or of snow on the ground, I realized that all that snow could give me a literal leg up on pruning. If I stayed on top of the snow, that is. While the snow was still soft, I was able to do this by strapping on a pair of snowshoes, which I bought, used, just for this purpose. (For travel through snow, I prefer to glide, on skis.) When the snow melted a little and then froze, the icy crust that formed was able to support my weight sans snowshoes.

In any case, when there’s a good depth on the ground, such as today, I gather my tools – minus the stepladder – and walk tall out to the trees.

Top Down Pruning

Plants, like other creatures, have hormones, and a hormone (called auxin) in every plant generally coaxes uppermost portions to grow most vigorously. Which is why old apple trees become topheavy, with most shoot growth high up. The upshot of this habit is that most fruit is borne high in the branches, out of reach, and lower branches are shaded to become unproductive and prone to disease.

Ideally, then, the best place to start pruning is with the most vigorous branches, highest in the tree. That’s also the last place you want to start if you’re standing at ground level. Perched atop a good depth of snow next to my smaller trees, starting near the top was much easier.

If I get high enough (in the tree), I can imagine that I’m hovering above the branches, looking at them from the perspective of ol’ Sol, which is a good perspective for a grower of fruit trees. This allows a more objective perspective on which branches are going to be blocking light or otherwise cramping others for space.
Pruning in snow
Letting more light and air in among the branches and, at the same time removing potential fruits with pruned branches, channels more of each tree’s energy into perfecting those fruits that remain. Remaining fruits are then healthier, larger, and more flavorful, especially for naturally larger fruits such as apples, pears, and peaches

Snow Tales

The snow is a blank canvas that records some winter activities. My dogs’ footprints are obvious and telling. They are provincial in their travels, having beaten paths from their doghouses, where they sleep, to the driveway, where they greet humanity, and to the deck, where they lie in the sun.

Daisy and Sammy at work

Less frequent are their forays out into the hay field to do their business and to see if anything interesting is creeping around out there.

The small, padded footprints of my cat hasn’t beaten out paths. The cat more randomly explores out-of-the-way nooks and crannies. She also likes to steer clear of the dogs, who consider her just another small animal worth chasing.

Gracie at work

The distinctive footprints that I’m keeping the closest eye out for are those of rabbits and deer. Now, about when I typically delude myself that all danger has past, periods of warmer weather start coaxing rabbits to wander about and eye my trees and shrubs as food. Now is also when cottontail rabbits start reproducing, the first of up to five litters for this year, with a half dozen or so bunnies per litter! Very cute, but deadly to my plants.

This winter, a couple of deep snows either brought deer here or displayed their abundance with tracks in the snow. For the rabbits, who feed on young trees and low branches, I sometimes make up a spray of white latex paint, water, eggs, cinnamon, and hot pepper. That needs to be re-applied about now. Traps I set out for them are thoroughly and safely (for the rabbits) buried in snow. Perhaps I’ll dig them out and re-set them.

The uncluttered expanse of snow makes it easy to see where I put my pruning tools as I prune the apples and pears. The snow also makes it easy to see where I drop the prunings.

Deer tracks in the snow

And why do I care where I drop my prunings? Because I can then quickly look at them to see if any bark has been gnawed off those freshly cut branches. And what would gnaw bark off those freshly cut branches. Rabbits!

No sign of rabbits – yet, at least – on those prunings as well as on tracks in the snow. Thank you Gracie (my cat).

The dogs’ are supposed to be keeping deer at bay, but do so only if they are out and about when deer are around. This year I’ve been relying on Bobbex repellent, which I spray monthly on branches that would be within reach of the deer. So far, the sprays have been 100% effective even on trees with deer tracks right beside them in the snow.

Get Ready for Spring

I will be hosting a WEEDLESS GARDENING webinar on Monday, February 22nd for $35. It will run from 7-8:30 pm EST and there will be plenty of opportunity to ask questions. For details, go to www.leereich.com/workshops. Or trust me, and go right to registration (required) at https://us02web.zoom.us/webinar/register/WN_WqSCBtOGTqqjGgbOHOuxfg