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From the Alfalfa & Forage News blog (April 29, 2022)
What is vetch? There are several species that are commonly grown as crops, cover crops or weeds (see list at the bottom). Vetch is a winter-hardy legume that's favored by early fall rains, which we had lots of last October (5.5-in in 24-hr in Sacramento). Vetch is also a nitrogen-fixing plant that works well as a cover crop in farming systems. It's also a good forage for bees and other pollinators and has extra floral nectaries (glands on stems that produce nectar) that attract beneficial insects like parasitoid wasps that prey on pests.
Is it a good livestock feed? Yes and no. As an annual leguminous vigorous herbaceous plant, vetch has high protein and relatively low fiber and reasonably high yields. It's vigorous growth and N fixing qualities is why it is so valuable as a cover crop, but it can also be grazed or fed as hay. Its quality is lower than that of alfalfa or clovers (protein levels from 15-20% depending upon stage of growth). It is commonly grown in mixes with small grains or grasses as a mix in different parts of the US. Vetch hay is difficult to handle due to the vine-like characteristics, and caution should be used due to anti-nutritional compounds and livestock palatability.
Anti-nutritional compounds. However, vetch hay can cause serious (and potentially fatal) animal health problems, so is not recommended as a primary forage for horses and cows. Most of the anti-nutritional compounds are concentrated in the seeds, so immature harvests are recommended. Vetch seeds are poisonous; they contain cyanogenic glycosides and a diglucoside that can cause a neurologic disease. Although hairy vetch (V. villosa) and purple vetch (V. benghalensis) seeds are the most toxic (being very closely related), other vetches have toxic seeds too, including common vetch (V. sativa). In addition, a toxin in vetch foliage is associated with a dermatitis or skin sensitivity disease, though this is extremely rare and not well understood. Most cases of vetch-induced dermatitis involve black cattle, such as Angus or Holstein, and horses can also be affected, so there may be specific susceptibility explained by a genetic predisposition. Lack of good information makes is difficult to assess vetch hay suitability for small ruminants like sheep, though there is anecdotal information that suggests it might be okay for goats.
How about rangelands? Vetch growing on grazing rangelands is actually a good, high-protein feed for livestock. In open range, cattle typically won't graze vetch until it dries down and seeds have shattered. On a hot day you can hear dry pods snap, crackle, and pop, like a bowl of Rice Krispies. Vetch is not favored by livestock when green due to low palatability (bitterness).
How about pastureland? Fenced pastures loaded with vetch going to seed could spell trouble for horses and cows, especially if there is little else to eat. Toxicity risk can be alleviated by ensuring other forage options are available and by stocking animals at very low densities and giving them the option to selectively consume non-toxic plants and avoid toxic plants. Again, once the plant has dried down and seeds have shattered (detached and fallen), it should be okay as grazing feed.
How big a problem is vetch toxicity? The California Animal Health and Food Safety Laboratory at UC Davis has had a few cases of vetch toxicity to cattle and horses over the years, but not many. It's still unclear if this means few cattle are exposed to vetch or few cattle actually develop disease. It's still kind of a mystery as to why vetch is sometimes a problem and other times not. It might be a matter of the degree of its presence in animal diets – low percentage is okay, high percentage more problematic. "Dose makes the poison" as a toxicologist would say.
How about croplands? Oats and vetch used to be a popular mix for feed, but not anymore and hay growers try to keep it out of their forage crops. If cereal grains are in a crop rotation, vetch seed is about the same size as wheat and barley kernels, making it hard and expensive to separate during seed cleaning. Vetch is also hard-seeded, meaning seed can lie in the ground dormant for years and germinate when not wanted, though the viability for most seed is about 5 years, allowing opportunities for management. For control, one can mow prior to pod and seed set or use broadleaf or pre-emergent herbicides if needed.
Vetch identification. To differentiate different species of vetch one needs to look at the flowers. Common vetch (V. sativa) has flowers with a short stalk (peduncle), meaning the flowers are attached close to the stem from where it originates (picture). Hairy vetch (V. villosa), purple vetch (V. benghalensis), and American vetch (V. americana) all have flowers with long stalks. Hairy and purple vetch flowers are aligned on one side of the flower axis (picture) whereas American vetch flowers are more upright (picture). Purple vetch will generally have flowers about the same size as the leaflets (picture), while the flowers on hairy vetch are generally larger or longer than the leaflet (picture).
What types of vetch are found around California on agricultural and rangelands? According to Dr. Alison Colwell, Curator, UC Davis Herbarium, the following are the rankings of vetch (Vicia) species abundance by county. This information comes from the Consortium of California Herbaria (https://cch2.org). The data are from all years that collections were made, which is basically the past 100 years. The take-home point of this analysis is that there are several similar vetch species that are all spottily dominant around California.
Yolo County (all ag)
- V. villosa (hairy; lana/woollypod subsp. varia)
- V. sativa (common)
- V. benghalensis (purple)
Mariposa County (mostly ranch/public land, central)
- V. americana (American vetch; native plant)
- V. sativa
- V. benghalensis
Butte County (part ag, part ranch, north)
- V. villosa
- V. sativa
- V. americana
Tulare County (ag, arid, south)
- V. americana
- (3-way tie) V. benghalensis, V. sativa and V. villosa
Stanislaus County (ag, central)
- V. villosa
- V. sativa
- V. americana
Original source: Alfalfa & Forage Newsblog (April 29, 2022)
- Author: Guy B Kyser
This has been a big year for purslane at the UC Davis farm. Common purslane (Portulaca oleracea) is a succulent summer annual weed with fleshy leaves and rubbery-looking stems. Native to Eurasia, or maybe Africa, purslane arrived in the Americas with the first Europeans to settle here. It is a common weed in row crops worldwide.
Purslane is a tasty vegetable, either raw or cooked, and sometimes appears in farmer's markets and grocery stores. It is reported to be high in omega-3 fatty acids.
It's also a royal pain in the neck as a crop weed. Each plant produces thousands of tiny, long-lived seeds. The brittle stems make it difficult to pull or hoe, and stem fragments left on the soil will readily re-root. I once participated in a cultivation study in beans infested with purslane; rows which were mechanically cultivated ended up with more purslane than non-cultivated rows.
- Author: Guy B Kyser
- Author: Mohsen Mesgaran
Dr. Mohsen Mesgaran, who joined the Weed Science Group this year as our weed ecophysiologist, found this plant growing on the research farm at UC Davis.
We have no idea how this plant got here. It is native to Africa, where the leaves are used as a vegetable; it is now widespread and invasive in many tropical to subtropical parts of the world. The USDA lists it as introduced in much of the United States southeast, from Texas to Virginia. Ellen Dean of the UC Davis Herbarium confirmed that the plant has not been reported in California before.
Mohsen and I pulled all the plants we found (a couple dozen or so), showed them to research farm personnel, and put the plants in the Plant Materials Bad Stuff dumpster for sterilization.
All photos are by Dr. Mesgaran.
- Author: Gale Perez
This just in from the UC Rice blog (http://ucanr.org/blogs/riceblog/). The author is Luis Espino, UC Cooperative Extension Rice Farm Advisor in Colusa-Glenn-Yolo Counties.
Japanese Millet
August 26, 2013
Japanese millet is not a weed of rice in our area. However, a PCA recently noticed it in an organic rice field. Japanese millet is in the same genus as our common watergrasses, and looks similar, but is much more robust. It seems to grow well under flooded and dry conditions.
The presence of this plant in the organic rice field was puzzling. Then the PCA learned that the field had been in pasture the year before. Most likely, the Japanese millet was part of the mix of grasses seeded as pasture and produced seed that survived the winter and germinated in the flooded rice field.
Unusual find, hopefully we won't see it ever again!
- Posted by: Gale Perez
- Author: Richard Smith
Cilantro was produced on 5,543 acres in Monterey and Ventura Counties in 2011. The production of cilantro has shifted to high density 80-inch wide beds and a large proportion is now mechanically harvested. Hand weeding high density beds is very expensive and reduces the economic viability of this crop. As a result, there is a need for excellent weed control. Two broadleaf herbicides were registered on cilantro: Prefar and Caparol. Prefar was registered for a number of years and provides good control of a number of key weeds in cilantro such as purslane, lambsquarter and pigweed. Caparol was registered in 2012 and provides good weed control of a wider spectrum of weeds including the nightshades, shepherd’s purse, sow thistle, groundsel and others (see tables below).
Here is the situation with Prefar: EPA moved cilantro (also Mexican & Chinese parsley) out of the "Leafy vegetables" crop group 4 and placed it in the "Herbs and Spices" crop group 19. The issue is that crop group 19 Herbs and Spices has no tolerance for Prefar. Without a tolerance, Gowan Corp. can no longer support the 24c for cilantro. It places growers in a tricky situation, because they may have Prefar with the old label in reserve, but any detectable levels of Prefar residues are detected on cilantro, it could result in seizure of the crop. This is a regulatory snafu that may take some time to untangle; work is being done to resolve this situation but it is unclear how long it will take to resolve.
Caparol is also registered for use on cilantro, but there is a plant back restriction of 12 months prior to planting lettuce, broccoli, cauliflower and spinach. This is of course very difficult to work with this restriction in the Salinas and other coastal valleys.
Other weed control options: bed fumigation of cilantro prior to planting can be highly effective, but issues with the cost and working around buffer zones makes this option difficult to fit into a grower’s production budget as well as schedule. Cultural practices such as pregermination followed by shallow cultivation of emerged weeds prior to planting can help reduce weed pressure. Cilantro seed germinates slowly which opens the possibility of burning off a flush of weeds (with an herbicide or propane flamer) following planting but prior to the emergence of the cilantro. This is a tricky, but highly effective technique for reducing weed density.
In summary, we have a number of regulatory issues that need to be addressed in order use the broadleaf herbicides without difficulty. We will need to continue to work with the regulators and registrants to resolve these issues as quick as possible.
(Click on tables and images to Enlarge)