Soil – Page 11 – Lee Reich

GOOD FUNGI AND BAD INSECTS

August 21, 2014/8 Comments/in Gardening, Pests, Soil, Vegetables/by Lee Reich

Fungi I Like and Bean & Japanese Beetles (Don’t Like)

Where once scorned or appreciated only after being sautéed in butter, fungi have finally come into their own. If you’re among those who isn’t awed by fungi except when they’re sautéed, swallow this: each gram of soil (the weight of a paper clip) might house over a million fungi, or anywhere from 10 to 100 pounds of them in the top 6 inches of a 1000 square feet of soil. And most of what they do — for plants and soil, forget about your taste buds for now — is beneficial.

I recently heard of a project using fungi as a building material. On exhibit at the Metropolitan Museum of Art’s PS1 in New York City is Hy-Fi, a cylindrical tower built our of bricks made from fungi that have been fed cornstalks, the fungi’s fine, thread-like hyphae growing to create dense bricks. An organically grown building! Among the benefits touted were that a building made of fungi could be recycled.

I’m not so sure that a building that can be recycled is a good thing, but one statement by the architect did raise my hackles: that the building could be made of waste materials, such as cornstalks. The same argument could be or has been used for ethanol production, which could be made from the same waste material.

Corn stalks might be waste material in the sense that we don’t eat them, perhaps not even always feed them to animals. But corn stalks, wheat straw, and other so-called “waste materials,” as the architect perhaps inadvertently pointed out, are a gourmet delight for fungi. Also good food for bacteria (3 million to 500 million per gram of soil), actinomycetes (1 million to 20 million per gram of soil), as well as protozoa, nematodes, and other soil creatures. And don’t forget about earthworms (2 to 22 pounds per 1000 square feet of ground). There’s a lot of hungry creatures down there.

So these materials are not waste; they are food for soil life. They are what put the “organic” in organic gardening and farming. (They are “organic” in the sense that they were once living, and that they contain carbon compounds, mostly combined with hydrogen and oxygen.) They confer a range of physical, nutritional, and biological benefits to soil, plants, and, hence the animals, including humans, that feed on them. Depriving the soil of these organic materials is what led, in part, to the dust bowls of the 1930s.

Corn stalks as well as other organic materials too often considered as waste should be returned to the soil, either directly or after being first run through a compost pile. One measure of soil quality is the amount of organic material it contains.

Waiting Out Japanese Beetles

Japanese beetles have not come into their own; they have never been and continue to NOT be appreciated. The swarmed in a few weeks ago to make lace of the foliage of a whole host of plants. Grapes are among their favorites, evident by merely looking out on the landscape and picking out the hole-y grape leaves. (The leaf veins typically remain intact.) Although roses are also a reputed favorite, the beetles left mine unscathed.

Kiwi foliage made lacy by Japanese beetles

Japanese beetles made lacework of just this hardy kiwi’s foliage

Most interesting is the beetle’s effect on my hardy kiwifruits, specifically the super-hardy sorts (Actinidia kolomikta). I have four plants, 3 females — Krupnoplodnaya, Aromatanya, and Sentayabraskaya — and one male. Of all those plants, only the Sentayabraskaya plant was attractive to the Japanese beetles, dramatically so. Looking up, I can see sky through almost every leaf.

Japanese beetles are hard to keep in check. For a few plants, hand picking into a can of soapy water (the soap so they don’t just fly out after a quick bath) is effective. The biological insecticide milky spore disease, applied to lawns to kill the grub stage in the soil, is sometimes effective, especially in more southerly locations. Of course, beetles emerging from the soil in summer can fly, so milky spore is useless unless done on a neighborhood scale. Neem is a relatively benign repellant and insecticide that’s somewhat effective sometimes; it would require too much spraying, especially for something with such an iffy effect.

So I just wait the beetles out. Plants can tolerate a certain amount of damage and the beetles typically wave goodbye to go burrow into the soil and lay eggs sometime in August. The wait was especially short this year, with most of the beetles departing by the third week in July. Thank you guys, and gals.

And Where Did Mexican Bean Beetles Go?

A Mexican bean beetle threesome

Other pests also come and go. Mexican bean beetles, mentioned last week, still are keeping to themselves, wherever that might be but not in my garden. Tomato hornworms, which are large caterpillars with voracious
appetites, stripping leaves from tomato plants in the matter of hours, turned up in a friend’s garden. Fortunately, piggybacking those beetles were what looked like grains of rice. They’re actually cocoons of a braconid wasp, which will kill the hornworm. Leaving parasitized beetles alone lets the parasite live to attack more hornworms.

Rice-like granules attached to tomato hornworm are parasites

Parasite attacks tomato hornworm; winner: parasite.

Also worth ignoring are the pimples that have been appearing on leaves of many pin oaks. Those pimples — hemispheres about 1/2” across — are galls. Plant galls are abnormal growth made in response to an irritant such as a bacteria, a fungus, or, most commonly, an insect. A few galls here and there rarely do a plant harm.

Those oak leaf galls are pocking almost all the leaves on my pin oak. Still, I’ll ignore them or admire them; they sort of liven up the look of the tree. It’s too late, anyway, to do anything about them.

Eerie White to Golden Flowers, with Some Fungi Helping Out

August 11, 2014/3 Comments/in Design, Gardening, Soil/by Lee Reich

White Indian pipes, mycorrhizae, and a golden flower

I do occasionally tear myself away from the farmden. So into the woods I went last Friday and as I was hiking along and glancing down at the trail, I came upon one of my favorite flowers. It’s a favorite not for its beauty but for what it hints at of goings-on beneath the soil surface.

The flower was indian pipes, Monotropa uniflora, an eerily white plant that looks like a upright tobacco pipe whose stem has been poked into the ground. Yes, it’s white. All white. You might rightly wonder how the plant synthesizes carbohydrates for energy and for structure. Photosynthesis, which makes carbohydrates, requires chlorophyll, which is green. Indian pipes don’t need chlorophyll because they get their carbohydrates from neighboring trees.

Join me while I go below ground. Stopping for a look at the roots of indian pipes, we see that they are infected with the fine threads of fungal hyphae. Now, if we follow the fine threads of the fungal hyphae out of the roots and through the soil, we eventually come to the roots of a nearby tree whose roots also are infected by one and the same fungus. A continuous connection exists from the tree to the fungus to the indian pipes.

The tree does have green leaves and, as with other plants, some of the products of its photosynthetic labors are channeled down to its its roots. Some of those products travel out the roots and into the fungal hyphae, and some of that is drawn out of the hyphae into the indian pipes for the latter’s sustenance and growth. Sounds like a one-sided relationship, a pretty good deal for the indian pipes. It is. The plant is a parasite, taking but offering nothing in return.

The relationship between the fungus and the tree, however, is symbiotic and called mycorrhizae (my-co-RYE-zay, which means fungus-root). Yes, the fungus sucks up some of the tree’s photosynthates, but in return it sucks up nutrients from the soil, then channels them back to the tree’s roots. The network of fungal hyphae in the soil is much more extensive than that of the roots, so, with fungal hyphae as “extenders,” the effective volume of soil “grazed” by roots is increased. Mycorrhizae are especially important for uptake of nutrients such as phosphorus, which roots (or their fungal extenders) must go out and find because it moves but little in the soil.

Myco . . . say what?

Wouldn’t mycorrhizae spur growth of garden plants? Yes. But look out your window; most of the plants you see are naturally mycorrhizal already. Still, deliberate inoculation might benefit young transplants. You can purchase inoculum, but the problem is that purchased inoculum often is not of fungal species best adapted to a particular location.

A better approach would be to keep your indigenous fungi happy. Limit tillage, which discombobulates the hyphae, grow a variety of plants, especially those that form mycorrhizal associations, and avoid pesticides. Also limit phosphorus fertilizers because they suppress mycorrhizae.

Another approach would be to grow your own mycorrhizal inoculant of local fungal species. Basically, you mix up a big batch of potting soil that has some indigenous soil in it and is not too high in nutrients. In this potting soil you grow a suitable host plant. (Not spinach, beets, or any plant in the cabbage family, none of which ever form mycorrhizae.) After the host plant dies at the end of the season, what’s left in the pot is indigenous fungal inoculum that can be added to a potting soil for growing seedlings. For more details, see http://rodaleinstitute.org/a-complete-how-to-on-farm-am-fungus-inoculum-production/. I use garden soil and compost in my potting mixes and assume there’s sufficient inoculum already present.

Grow Some Gold

As I rounded the bend at the back of my garden after my woodland hike, I came face to face with a flower I had planted temporarily back there, giant knapweed (Centaurea macrocephala), also known as Armenian basket flower, globe centaurea, and yellow hardhat. Plants with too many common names are usually suspect to me, and none of this plant’s names have a particularly nice ring to them — yet this plant is a showstopper.

From the whorl of rather coarse leaves at the base of the plant rises a sturdy flower stalk. At almost 4 feet high, a big fat bud forms atop the stalk, a bud that looks like a globe artichoke that has been gilded. Nice enough even then, but a couple of weeks later — which is now — a bottlebrush of lemon yellow petals spills forth from the top of the bud.

Globe centaurea, the name most euphonious to my ears, tolerates heat and cold (USDA Hardiness Zones 3 to 8), and is relatively carefree. No need to prop the flower stalk up with a stake. The blossoms put on their show for about a month, not counting the gilded opening act, and hold up well as cut flowers, or can be dried.

Globe centaurea deserves more attention over much of the country, except perhaps in the Pacific Northwest, where it’s considered invasive. I grew it years ago, and it disappeared. Nice to have it back.

Peas Please Me

July 18, 2014/1 Comment/in Soil, Vegetables/by Lee Reich

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.