Pasture and Forage Minute: Toxic Plants, Managing First-Year Alfalfa
Poisonous Pasture Plants
While generally not as problematic in Nebraska compared to other western states, poisonous plants can exact their toll on livestock enterprises, and many times the losses are unrecognized.
There are 17 species listed as primary toxic plants that can be found in Nebraska. Toxic plants contain or produce substances injurious or lethal to animals. The amount of plant material consumed by the grazing animal before death or poisoning symptoms appear varies by species. Poisoning symptoms will vary depending on the toxic compound in the plant, but may include difficulty breathing, excess salivation, nervousness or staggering. Many poisonous plants are avoided by the animal, but a scarcity of forage — such as under drought conditions — may lead to a situation where they are consumed.
There are some species, such as prairie larkspur, where grazing animals may select for them when they are flowering (mid-June to early July). Other relatively common poisonous plants in central and western Nebraska include Riddell groundsel, Lambert crazyweed, wooly locoweed and chokecherry.
Poison hemlock and spotted water hemlock are common statewide. These two species prefer moist areas in pastures, creek banks, ditches and disturbed sites.
If you suspect a poisonous plant problem in your pastures, be sure to get a positive identification of the plant. When control or removal of the plants is not possible, it may be best to move livestock to a different pasture.
Nebraska Extension does have a great resource called Nebraska Plants Toxic to Livestock (EC3037) that can be found online or obtained through your local extension office.
Clover Toxicity and Horses
Did you know clover can cause toxicity in horses? There are three clovers you should be able to identify that can cause problems for horses: red, white and alsike.
Red and white clover are not toxic on their own, but a fungus that causes black patch — a common disease — is toxic. This fungus produces a toxin that causes excessive drooling or slobbering in horses. While this might be unsettling to witness as an owner, the condition is usually not life threatening but can cause dehydration. This toxin can be found in both pastures and dried hay if the clover was infected. This disease likes cool, wet weather, so if these conditions are present, keep an especially close eye out for symptoms like bronze to black spots on the stems and leaves.
Alsike clover is another clover that can be found in pastures. With an appearance similar to red or white clover, you can identify this clover by its multicolored flowers, which are dark pink at the base and light pink towards the tip. Additionally, leaves will be serrated with no distinct white “V” shape commonly found on red and white clover leaves. Once again, a fungus infecting the clover is what is responsible for the toxic symptoms seen in horses. Two serious conditions can be seen in horses from this toxicity — photosensitization and big liver syndrome. Photosensitization causes the skin to react to the sun rays, resulting in what looks like a bad sunburn; however, in some cases the skin dyes and may slough off entirely. Progressive destruction of the liver, known as big liver syndrome, can occur after long-term exposure to the infected clover and results in liver failure.
So, what can you do to protect your equine? First, properly identify clover that may be present to get an idea of the risk. Herbicides may be used to thin or remove clover from your pastures if desired. During periods of wet/humid weather, fence off large patches of clover, or keep patches of clover mowed short to prevent the favorable conditions for the fungus.
Managing Seeding Year Alfalfa
Alfalfa seeded this spring is ready, or soon will be ready, to cut. Proper care and management now could have big impacts on cuttings later this year. Use the following harvest guidelines to get the most from your first-year alfalfa.
Seeding year alfalfa is different from established stands. Stems are spindly, roots are small and shorter, and growth is a little slower.
You can harvest seeding year alfalfa as early as 40 days after seedlings emerge. Again, this is 40 days after emergence, not planting. Alfalfa takes about 40 days to develop the ability to regrow from the crown after cutting. Plants cut before this point need at least one set of leaves remaining to regrow. So, if you need to cut early for something like weed or insect control, cut high.
Although alfalfa seedlings can be harvested 40 days after emerging, I think it’s better to wait until around 60 days after emergence, at late bud to early bloom stage, before the first cutting. Yield will be a little higher and plants will withstand weather stress easier with a little extra growth. This extra time also allows increased root development, helping avoid problems from soil compaction or surface soil dryness.
After the first cutting, regrowth of seedling alfalfa will become more similar to established alfalfa, giving you the opportunity for two or three cuts the first year.
One last point — while it may seem like a long way off, never cut seeding year alfalfa during the four-week period before a killing freeze. Winter injury can be severe due to reduced winterhardiness of new plants. Look ahead at the calendar now to plan when future cuts might be taken to avoid cutting during this sensitive time.
First year alfalfa can be productive, just manage it right.