WEEDS, PESTS, DISEASES, AND GARDEN ECOSYSTEMS

“Good and bad I define these terms, quite clear, no doubt, somehow. Ah, but I was so much older then, I’m younger than that now.”

This snippet from Bob Dylan’s My Back Pages brings to mind a story:

In our ancestors’ early days of food-gathering and food-growing, the words “good” and “bad” did not apply, except perhaps as a measure of edibility. What we eventually came to call weeds, pests, and diseases were simply parts of the natural balance, or indicators of an imbalance being corrected. Not until human beings started to assume that they were, and should be, in charge of ecosystems did they begin laying down the judgments implied by the terms weed, pest, and disease. That is, until they had forgotten about the hand that fed them, they didn’t start biting it, rhetorically and otherwise.

Fast-forwarding thousands of years, we arrive at modern agriculture, which has developed a panoply of chemicals to eliminate “bad” members of the ecosystem. In the eyes of the contemporary industrial farmer, what we now call weeds, pests, and diseases are without merit—in fact, they are enemies in the battle to crank out as much commercial product as possible. In recent decades, the ecological feedback loops described in the Beetless’ MOTHER NATURE'S WON [0] have become ever-more painfully apparent, and yet the industrial agricultural establishment has given scant indication of listening, even as it becomes less and less successful in its war on nature. Because of the forces of evolution and natural selection, weeds, pests, and diseases have multiplied even faster than the chemicals employed to combat them.

Enter a new generation of gardeners and farmers, who are starting to re-discover the long-ago “young” wisdom of our distant food-gathering and gardening ancestors. These new food-growers see “weeds,” “pests,” and “diseases” as our friends, or at least as useful allies.

Plants usually labeled “weeds” can in fact serve many functions, as the Beetless remind us in PLEASE WEED ME [0]. First, weeds are often more nutritious than the crops we are growing deliberately, and can serve an important role in human nutrition. A fascinating chart on page 96 of Robert Kourik’s Designing and Maintaining Your Edible Landscape—Naturally compares nutrient content of several cultivated greens with “wild edibles” usually classified as weeds. Nettles tops the chart for protein content (at 7 gms/100 gms), followed by lambsquarters and then kale (a frequent volunteer vegetable here) (both above 4 gms/100 gms) and then amaranth (at 3 ½), which edges out spinach. Dandelion comes in at 2, followed by purslane, chicory, and dock. Iceberg lettuce is at the bottom of the chart, with less than 1 gm/100 gms. Iceberg lettuce also resides at the bottom of the chart for Vitamin C (in which kale is off the high end, with amaranth, lambsquarters, and dandelion close behind), Vitamin A (where dandelion, lambsquarters, dock, and kale top the list), iron (where amaranth and purslane are highest, with nettles unknown), and potassium (where spinach edges out chicory, amaranth, and kale, with nettles, lambsquarters, and purslane unknown). Only in amount of calcium does iceberg lettuce reach the top four of these ten greens, but lambsquarters, amaranth, and kale still surpass it.

Lambsquarters and amaranth, abundant summertime weeds in our gardens, can be eaten either raw or cooked as spinach substitutes. Dandelions, chickweed, and chicory, which thrive in cooler weather, make excellent salads, either on their own or combined with other greens. Any of these plants can also be incorporated into pesto, soups, baked goods, etc. The nutrition to be found in wild edibles like these and others which grow here finds brief but significant expression in the Beetless’ I SAW HERBS STANDING THERE [0], a portrait of a thriving backyard ecosystem in which flowers, bees, birds, trees, vegetables, and herbs all happily coexist.

Weeds also serve as helpful indicators of soil conditions. For example, lambsquarters indicate fertile, cultivated garden soil; sorrel and dock indicate acidity; quackgrass and bindweed indicate hardpan; Canada thistle, sow thistle, and English daisy indicate clay.

Weeds serve as dynamic accumulators, concentrating and bringing nutrients up to the surface, often from the lower reaches of the soil. When these weeds become mulch, humus, and/or compost, these nutrients are made available to other plants. Thistles, for example, are excellent iron accumulators; clovers fix and concentrate nitrogen and phosphorus; mustards specialize in sulfur and phosphorus; chickweed concentrates potassium, phosophorus, and manganese; and lambsquarters concentrates these three plus nitrogen and calcium. (These figures come from a chart on page 269 of Kourik’s Designing and Maintaining book.) At the same time, these weeds improve soil structure; roots provide organic matter to the soil when they die, and taproots, especially, improve drainage as they decay.

Weeds attract beneficial insects which help keep “pest” species in check. (See the Beetless’ BUG ME DO [0].) Members of the Apiaceae (carrot family, which includes Queen Anne’s lace, fennel, and other umbelliferous plants) and Asteraceae (daisy family, which includes dandelion, all seventeen of its near-look-alike “DYC”s [a.k.a. “D---ed Yellow Composites], and a huge number of other species bearing composite flowers) are especially favored by predatory insects. Members of the Brassicaceae (mustard family) also produce flowers that frequently swarm with insect friends (like the Hymenoptera who are the buzz in AND YOUR BEES DON’T STING, from the Beetless’ APPENDIX [0].) In fact, almost any plant that bears flowers will help keep species of beneficial insects and pollinators up. Weeds allowed to go to seed will also attract birds, many of whom do their share of insect-control as well.

Weeds can act as cover crops, protecting soil from erosion and turning sunlight, air, water, and minerals into organic matter through photosynthesis in places where no other plant is doing so.

The many benefits of weeds suggest one obvious question: Why would anyone want to “weed” them?

The simple answer: Too much of a good thing can be too much of a good thing.

Weeds can interfere with the growth of other plants, outcompeting them for sunlight, water, nutrients, and physical space both above and below ground. Some weeds, like fennel, can emit chemicals which impede neighboring plant growth. Weeds can harbor slugs or other pest species. Some weeds put out so much seed that, if not removed before seed ripening, they may increase their population manifold in the following season. Weeds can cut down on air circulation in the garden, encouraging the spread of disease. Weeds can obscure the crop plants, making vegetables difficult for a gardening novice to identify and harvest. Weeds can cause abrasions to gardeners attempting to work around them, and, if growing in paths, can result in sopping-wet shoes on rainy days. In short, there are compelling reasons to remove them on occasion.

Most weeds we remove only situationally, weighing their benefits and drawbacks. Only when the latter outweigh the former do we choose to give them the ax, kama, hoe, glove, bare hand, scissors, or scythe.

But certain perennial weeds are virtually always on our “hit list.” These include, most significantly, two rhizomatous species, quackgrass (Elymus repens) and bindweed (Convolvulis arvensis), which form such thick networks of underground stems in the soil that they weaken and eventually crowd out most other plants. When severed, these rhizomes can generate a new plant from each piece. They know no bounds, no modesty. They are invasiveness distilled and magnified.

Yet even they have their place in nature, and their own redeeming qualities. Their main redeeming quality in our gardens is that they stimulate us to fork through the soil very thoroughly in order to remove them, thus increasing our contact with the earth and ultimately improving soil drainage and tilth as we add organic matter in the process. Thoroughgoing attempts to remove quackgrass and/or bindweed are essential each time we prepare beds; otherwise, before we know it, Houston, we have a problem. Populations of these two weeds have decreased wherever we have concentrated on removing them. Often a result of tiller-compacted hardpan (which harbors networks of runners just below the polished soil level created by whirling tiller tines), they yield to persistent hands-on control measures and soil improvement efforts.

We don’t add quackgrass or bindweed rhizomes to our regular compost piles, because any one surviving piece can infiltrate the entire pile and result in a population explosion once that compost is spread. We dump these rhizomes in a separate pile outside of the garden, or feed them to the chickens, who eventually turn them into eggs.

Several other perennial weeds fit into this category, although none are as prevalent here as the two already mentioned. These weeds are all either rhizomatous/creeping/spreading, have taproots that, when broken into pieces, generate multiple plants, and/or feature painful spines that draw blood. They include buttercups, sorrel, dock, comfrey, blackberry, Canada thistle, and several other pain-inducing thistles—all of whose rhizomes and/or roots we remove from the garden whenever possible and keep out of the regular compost piles. (Some of the most problematic thistles may indeed be vigorously self-sowing annuals or biennials; things like that hardly seem to matter when one is bleeding and not in the mood to grab a botanical key to find out.)

Pests and diseases are often demonized as much as weeds are, but in most cases, we see them, too, as allies in our quest for a balanced garden ecosystem. Pests and diseases have been variously described as “quality control engineers” (by Uday Bhawalkar) and “nature’s censors” (by Sir Albert Howard). In most cases, an insect infestation or a disease indicates an imbalance in the garden ecosystem, a weak plant, and/or unhealthy growing conditions for the plant.

We have very few pest infestations in the Lost Valley garden, but when we do have aphids, for example, they invariably attack a plant that we would not want to eat anyway because it is under stress and lacking in proper nutrient balance (which their presence helpfully indicates to us). Aphids typically congregate on over-the-hill, overheated, out-of-season cool-loving brassicas, and on plants that are unhealthily rich in nitrates (a problem we don’t usually have, but which has been observed on overfertilized plants in Eugene). When insect infestations or diseases appear on other plants, we know that those plants, too, are stressed and unfit for human consumption.

We attempt to guard against the spread of disease by following healthy cultural practices, which include assuring ventilation of greenhouses (as noted in the discussion of Greenhouses and Season Extension Methods [0]), minimizing lingering moisture on the leaves of disease-prone plants (as described in the Irrigation [0] section), and providing adequate air circulation around them (as noted in the weeding tips above). We also remove diseased plants from the garden. We do not always go out of our way to remove insect-infested plants, because they may be providing necessary food for beneficial insects and are sometimes acting as “trap crops” that prevent other crops from being infested. If they look really terrible, though, or if gray aphids get smeared all over someone’s nice t-shirt, then they’re up the same dry creekbed that concluded the Irrigation [0] section.

There is one class of pest that does NOT indicate imbalance in the garden ecosystem, except for the imbalance caused by the pest itself. These are creatures that eat healthy, choice produce, rather than filtering out that which wouldn’t be fit for humans. We have three major ones:

1. Slugs (and their close cousins, snails). Slugs love moisture, and they also love tasty young greens. In fact, they’ll eat just about any vegetable matter, especially if it’s appealing to us humans. (They’ll also eat other dead slugs—these have proven less appealing to most people who’ve tried them.) Our main methods of slug-control consist of habitat reduction (clearing or trimming down areas near newly-planted and slug-prone crops), hand-collection (especially in the evenings, at night, and in early morning—slugs make good chicken food), and trapping (slugs congregate under boards laid in paths; they are also attracted to containers filled with beer, or even better, a molasses-yeast-water mixture). Field Guide to the Slug, a fascinating look into the world of these slimy, moisture-loving creatures, is guaranteed to instill appreciation for these amazing gastropods, and also gives further suggestions for control. The Beetless’ ode to our number one garden pest, HERE COME THE SLUGS [0], mentions a technique for which the group’s popularizer no longer has the heart: chopping them in two. (AND I SLUG HUNT, from the Beetless’ APPENDIX [0], remains ambiguous on this matter.) Strangely enough, since he stopped chopping them in two, they seem to have become much less of a problem. Snails are less numerous than slugs here, although in parts of Eugene that used to be sea floor, they can be just as numerous as slugs, or more so (snails make their shells from calcium). Snail populations have been climbing slowly, perhaps because of all the oyster-shell flour we’ve applied to the garden.

2. Gophers (and moles, voles, etc.). Tunneling underground rodents like moles, voles, and gophers (see GOPHER BITES [0], and, from the Beetless’ APPENDIX [0], DEAR RODENTS) are a mixed blessing. They help with drainage, but they can also disrupt plant roots, and (in the case of gophers and voles) eat those roots or even whole plants. Before being eaten, those plants were perfectly healthy, so gophers and voles, like slugs, are nature’s “quality control engineers in reverse,” choosing to eliminate some of our best plants. Plants most susceptible to becoming their dinner include parsley, carrots, other Apiaceae family members, other root crops, and tubers like potatoes and yacon. Trapping is possible, but we haven’t tried it. We plant susceptible crops in several different places in the garden, hoping these rodents won’t find them all; we encourage snakes; and we pray.

3. Deer. Given open access to the gardens, deer would eat them to stubble. Our deer fence is what keeps us in food. It’s that simple.

We also have three major pests that have caused disruptions with our seedbeds, seedflats, and seedpots: cats, birds, and small rodents. Cats like to scratch up bare ground in which seeds have just been planted, a proclivity bemoaned in the Beetless’ ACROSS THE SEED BEDS FIRST [0]. Birds seem to love lettuce seed especially, as well as tomato seed and others, and will pick them out of seedflats if allowed access. Mice and other small rodents will choose squash and cucumber seed first, then go for beans, corn, and peas—whether they’re in an inadequately sealed seed bin, or have just been planted in pots (or sometimes even in the ground). Birds sometimes take a liking to newly-sprouting peas or favas as well. In all of these cases, exclusion is the only practical response: keeping cats away from seedflats and seedbeds, keeping birds out of seeding areas if possible (or, at the very least, covering individual seedflats with upside-down trays or other barriers that do not allow acces), and starting vulnerable seeds in containers that are adequately rodent-protected. Because of cat, bird, and small-rodent predation, we have had to resow our lettuce, tomato, squash, cucumber, and pea crops multiple times on occasion. These inconveniences have led us to devise ever-more-elaborate (and, luckily, effective) methods of preventing them access to our seeds and seeding areas.

Ultimately, because of the diverse garden ecosystems we cultivate and encourage, and because of the easily-appreciated benefits of most of the plants and creatures that volunteer themselves in our gardens, any headaches that weeds, pests, and diseases might cause us are decidedly low-key. In terms of protecting our food supply, most of us have far more to worry about from fellow human beings, as the Beetless remind us in YOU’VE GOT TO HIDE YOUR GRUB AWAY (listed in the Beetless’ APPENDIX [0]; lyrics lost).

 
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