AgriCulture bloggers Peter Davies and Mark Scherzer are the owners of Turkana Farms in Germantown, NY. This week, Mark writes: It is still late Spring, though the recent stretches of extreme heat and the explosion of vegetation read more like mid summer. In the late afternoon sunlight, the pasture is topped with a foamy white mantle as a prolific plant with tiny white flowers enters a period of vigorous bloom. While from a distance, it's quite pretty, my walks across the pasture convince me that this plant is not a benign presence. Its long vine-y stems, sparsely populated with occasional clusters of leaves, create dense mats that seem to shade out and kill all the grasses and other plants beneath it. What's worse, while the cows and sheep both seem to crave variety in their grazing, neither seems to like this plant at all. Where it is dense, the intertwined grass is uneaten. The apparent beauty of the pasture may not be appealing at all to our resident ruminants. We can't address the problem without first understanding it. We thought, based on appearances, that this might be bird's foot trefoil, because part of the leaf and stem configuration could be taken for a bird's foot. Except on further investigation, bird's foot trefoil is apparently much coveted by cattle, and it blooms yellow. Casting about in on-line descriptions and depictions of weeds, I’ve decided it must be either chickweed or webstraw (aka goosegrass). Visually, it seems closer to webstraw (galium aparine, photo above), but it lacks the stickiness mentioned in descriptions of that plant. If anyone reading this knows otherwise, I'd love to hear about it. Some descriptions of both chickweed and goosegrass claim that their leaves are edible, and some claim that chickweed is to the taste of various animals. To me this invader, whatever it is, seems to lack redeeming features. I’ve decided it requires eradication if we are to continue to provide our ruminants with high-quality forage and our customers with the resultant high-quality meat.
Thus comes the question of how to eradicate. Lots of agricultural extension websites recommend Roundup as a relatively benign herbicide without long lasting residue, but even that level of herbicide is more than we want our animals to ingest. Other authorities claim that manual removal is preferable, but warn that failure to remove the entire root can accelerate the weed's spread. The prospect of weeding more than 20 acres of pasture by hand is simply not feasible, however. So, for now, I am following a routine, taking a few moments to pull a hefty armful of weeds at each feeding of the sheep. I pull out about a five-by-five foot area in the badly affected zones, and feed it to the chickens. The chickens don't show nearly the same enthusiasm for this as for some of the other weeds, whose names I have yet to learn, that they clearly consider treats. Turkey poults, luckily, are quite enthusiastic, and Peter suspects the goslings will be too. But I like the idea of finding a positive use for a damaging pest, and I intend to pursue at least this incremental strategy methodically.
I am far less ruthless about rooting out other weeds in other contexts. In the vegetable garden, I almost always give dill a free pass. It is amazingly prolific, and self-seeds with abandon. I now understand why they call it dill weed. But it is easy to dry for year round use. At this point in the season I also am quite indulgent of purslane and lamb's quarters. In a couple of weeks, the purslane will provide us with a vitamin-C rich, succulent side dish, mixed with yoghurt, garlic and salt in the Turkish style. Right now is the perfect time to be picking lamb's quarters. Chopped and lightly sauteed or wilted as greens, they are rich in oxalic acid. I make big batches and freeze most of it for winter. It freezes far better than spinach. That works out fine because we are enjoying eating our way through the abundance of fresh spinach that's coming in right now. Peter is often irritated by my protective stance toward purslane and lamb's quarters, especially when he sees them overwhelming the planted vegetables. But I can sense an even more difficult discussion looming about how to deal with the crowd-out effects of a much larger member of the plant kingdom. The year we moved into the farm, one of our new neighbors gave us several black walnut seedlings he had started. These trees are valued for the quality of their wood and nuts, as well as their stately presence in the landscape. We understood vaguely that black walnuts had some mechanism to poison the soil against competing growth, but knew very little about how that worked. Peter assumed it was the nut shells, operating the way sunflower seed hulls do.
Now we're learning. Two of the black walnuts we planted were interspersed with a row of currant bushes back near our woodpile. They all coexisted peacefully, even flourished, for the last nine years. Suddenly, about three weeks ago, Peter asked me if I had noticed that several of the currant bushes had died. In my usual absorbed fog, I had not noticed. Having pruned them all a few weeks before bud break, I had seen nothing unusual. But sure enough, six or eight bushes had failed to leaf out. And it was surely no coincidence that they were the bushes in close proximity to those two black walnut trees, which are now about 15-20 feet high. Doing some belated research, I now learned that juglone, the substance emitted by the tree, is particularly lethal for several varieties of berry bush, as well as for potatoes, tomatoes, cabbage, peppers and eggplant. The substance is emitted from the tree's roots. It is also found in the leaves, which if left on the ground will leach juglone onto the surface soil. The poisoning effect can extend up to 50 feet from the tree's drip line. Now we have a real problem. As these two black walnuts grow, I expect that their drip lines will likely extend to within 30 feet or less of our vegetable garden. I trust that the appearance of the poison effect this year demonstrates that the trees are maturing and may start blessing us with crops of walnuts, but now we must make a decision. Are they in effect predator weeds that need to be eradicated for the sake of the vegetable garden or are they major assets we'll have to work around? Let the debate begin. —Mark ScherzerFor the complete archive of past AgriCulture blogs, click here.
