Last growing season I took a few soil samples on a southern Herkimer County dairy farm. One of the fields being sampled that I found particularly interesting had been planted to a mix of forage soybeans and brown midrib sorghum two weeks earlier. There appeared to be more soybean seeds just sprouting, and laying on the soil surface, than there were emerged seedling plants with two, three or four true leaves. Emerged sorghum plants were few and far between.
In the preceding two weeks, local weather conditions had varied all over the board, from the low 40s to the low 90s. Moisture conditions ranged from adequate to parched. For soybeans to germinate optimally, soil temperature should exceed 60º F, and sorghum seeds prefer a constant minimum of 65º for their successful germination. While the host farmer and I were taking soil samples, about a hundred yards away a flock of pigeons was enjoying the sprouting soybeans.
I could see some soybean plants with small but distinct true leaves. Examining this foliage closer (even though the leaves were only a half-inch wide), their surfaces felt soft and a little fuzzy, ruling out soybeans. I had to tell my host that these were velvetleaf specimens.
Some background on velvetleaf (Albutilon theophrasti) is in order. Researching a textbook, “Weeds: Control Without Poisons” (Acres USA, 1996), we learn that this annual plant causes trouble for crop growers in all but the coldest parts of North America. It reproduces by seeds, usually in tilled fields, and – as its common name implies – it has a velvet touch on both sides of its leaves. When crushed, those leaves don’t smell good. Its simple leaves alternate and can be up to 12 inches wide. Its flowers, mounted on short stalks, are orange-yellow, and their resulting fruit splits upon maturing.
Quoting textbook author Charles Walters, “It proves troublesome in row crops. The remedy is cultivation, cutting or pulling. (Chemical) poisons are not particularly helpful, because their seeds retain their vitality for over 50 years. Only the well-inoculated compost pile will kill them. The appearance of velvetleaf is an early warning system, with specifics attached. It says that decay has gone in the wrong direction, with methane rather than carbon dioxide (as) the byproduct. Phosphates in the soil are complexed, and (beneficial) aerobic micro-organisms have gone off-duty.”
Walters also stressed that velvetleaf soils have a carbon problem, and that fertilizing with muriate of potash and commercial nitrogen also guarantees that this unwanted plant pest will stick around. Herbicides seldom solve the velvetleaf problem, since this weed skillfully develops resistance to them. Velvetleaf’s presence is usually proof that calcium and phosphorus levels are low or complexed – and that potassium, magnesium and, very likely, selenium are high.
Quoting Walters again, “With anaerobes in command, manganese, iron, sulfate, copper, boron and chlorine are cut loose, and achieve a high profile. Low humus, low porosity and poor decay translate into high moisture, crusted and sticky soils and aluminum release.”
He pointed out that, almost illogically, use of classic herbicides, like alachlor and 2,4-D, improve the overall vitality of the velvetleaf population. Newer herbicides don’t have a much better track record. This almost guarantees chemical failure, because killing the inferior (herbicide-susceptible) specimens simply leaves the survivors to reproduce.
To me, this is case where otherwise learned weed scientists continue to fail “Population Genetics 101.” In addition to velvetleaf’s background (just discussed), here’s some of its history. This weed originated in either China or India. Its use as a fiber crop in China dates at least as far back as 2000 BCE. It is still grown there for fiber, which is used to make ropes, coarse cloth, paper and caulking for boats.
Whether as foreign material in crop seed or as an intended fiber crop, velvetleaf arrived in North America mostly likely before 1700, becoming widespread on the East Coast by the early 1700s. Although attempts to process velvetleaf never succeeded economically, U.S. farmers continued to cultivate it for more than 100 years. In the minds of most farmers, A. theophrasti’s minuses far outweigh its pluses.
But, giving the devil his due, there are some nutritional benefits: Seeds can be consumed raw or cooked; they can be eaten raw when they are under-ripe. Ripe seed can be dried and ground into powder, then used in soups, bread, etc. The seeds contain between 15% and 30% oil, but those yields (on a per acre basis) compete poorly with oil yields from soybean, corn, sunflower and canola.
Also in southern Herkimer County is a farm where I used to cow-sit almost 30 years ago. In the time since then, the farm has changed hands twice. Milk is no longer shipped from that location, since a very large dairy operation nearby needed land for its expansion. A couple weeks ago, I drove by the farm where I cow-sat way back when, and passed by a parcel that had, one owner ago, been part of an organic rotational grazing program. The current crop grower had planted herbicide-tolerant soybeans, but it took a lot of effort for me to find the beans, because they were so swamped with velvetleaf – probably the worst infestation of this broadleaf I’d ever seen.
I know for a fact that this prolific stand of A. theophrasti had survived at least one barrage of chemical warfare. The seed had likely been delivered in liquid manure from the large dairy herd that the “soybean” parcel was supposed to support. A significant amount of now herbicide-tolerant velvetleaf seed had apparently survived the oxygen-free slurry environment, as well as the cow’s digestive juices. Looks like someone should sign up for “Population Genetics 101” summer school.