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Published May 31, 2008, 12:00 AM

Will's Windmill column: Hoary Alyssum in hay, pasture and forage

Hoary alyssum is a weed common to Hubbard and Becker Counties and throughout Minnesota, the surrounding states, and Canada.

Hoary alyssum is a weed common to Hubbard and Becker Counties and throughout Minnesota, the surrounding states, and Canada. It is particularly adapted to dry conditions such as occur on sandy or gravely soils. Hoary alyssum is a member of the mustard family and is perennial in its growth habit. Hoary alyssum tends to increase in forages following drought or winterkill, regardless of the soil type of the field.

As with any weed control program, proper pasture and hay management is the first consideration. This includes annual fertilization of pastures, seeding adapted species, and controlled grazing to avoid overstressing desirable forages. For hayfields, proper soil fertilization and seeding to insure adequate forage stands that are vigorously growing and competitive will help to prevent high levels of alyssum developing. Winterkill can open some alfalfa stands to invasion by alyssum, in which case the most appropriate method of control would be to re-establish the hay crop. Remember, adequate alfalfa stands should contain 5 plants per square foot in third year or older stands to have adequate populations remaining to merit continued economic hay production.

If herbicides must be used, the most effective in pure alfalfa are products applied to dormant stands or following first cutting. There are no other good herbicide options for controlling alyssum beyond the first cutting. For grass pastures, of the various broadleaf herbicides available, the most economical approach would be to apply 2,4-D in the spring or fall to suppress hoary alyssum. Re-treatment will likely be necessary. No broadleaf herbicides are labeled for use on grass/legume mixed pastures that do not have significant injury potential to the legume as well.

Hoary alyssum is not a known poisonous plant as we typically think of plants such as

hemlock, bracken fern, nightshade and white snakeroot. Considering the widespread distribution of alyssum in Minnesota and the lack of reported toxicity to animals, it is of relatively low toxicity to livestock in that sense. Complete avoidance of hoary alyssum in hay or forage is not an economical or environmentally sound goal.

For ruminants, the buyer should be aware of potential concerns when feeding hay containing hoary alyssum, though horses appear to be at greater risk to date. The buyer should be aware of the clinical signs and monitor ruminants for any indications of toxicity, and remove alyssum-infested hay if problems develop.

For horses, hay producers and horse owners both should be aware of toxicity symptoms and management needs regarding hay that may contain low levels of hoary alyssum. Buyers should be alert for clinical signs of toxicity development and immediately remove alyssum-infested hay if symptoms develop. Hay containing greater than 30% hoary alyssum should not be fed to horses.

For information on hoary alyssum, request University of Minnesota Extension Service Bulletin FS-5567-GO from your County Extension Service. For control of hoary alyssum in township, county and state right-of -ways, contact your township supervisors, and county agriculture Inspector. For more information, please contact me: Will Yliniemi, Hubbard/Becker County Extension Educator at 1-218-732-3391, 1-218-846-7328 or by cell at 1-218-252-1042, or by email at ylini003@umn.edu .

Controlling Poison Ivy

Several people have recently called the office to ask for advice on how to control poison ivy. Poison Ivy growth and spread has been rampant in the last few years in this area. It is important that an organized plan of attack be instituted in order to do a good job of poison ivy control. Remember that poison ivy is on the noxious weed list in Minnesota.

Poison ivy can be distinguished from other plants by its leaves, which are always divided into three leaflets. It is these, which are referred to in the old warning, “Leaves of three, let it be.” These leave, each consisting of three leaflets, alternate on the stem. Each leaflet is oval-shaped, pointed at the tip, and tapered at the base. The middle leaflet has a longer leaf stem than the two side ones. Leaflets may be slightly lobed or coarsely toothed. When some leaflets are lobed, people may call these plants “poison-oak,” but true poison oak does not grow in Minnesota. There are only variations of poison ivy.

The leaves’ surfaces may be smooth or hairy, glossy or dull. They can vary in color from yellowish-green and green to reddish-green. Poison ivy fruits, which develop in fall, are small white berries with sunken ribs.

Poison ivy is best controlled with a herbicide containing triclopyr, a woody brush-killer. It should be applied directly to the leaves of the poison ivy, not soaked into the ground. When used according to directions, this herbicide should not injure established grasses, only broad-leafed plants. Apply the herbicide when poison ivy is growing actively. Temperatures should be in the 60° to 85°F range. Avoid windy days when droplets might drift onto the foliage of nearby trees, shrubbery or garden plants.

You may have to spray more than once since poison ivy is a tough plant to kill. Wait two weeks or more between applications and repeat only if weather permits. Don’t apply herbicide after poison-ivy foliage begins to show fall color. Wait till new leaves are fully expanded the following spring.

Some resprouting might occur several months later. Watch the area for at least a year and repeat the treatment as needed. As with any garden chemical, read and follow label directions carefully each and every time you use it.

Be very careful cutting down poison ivy, as all parts of the plant are poisonous. Note, too, that even the dead plants are poisonous. Never burn them! Smoke and ash can carry toxins to the skin causing a rash. Inhaling the smoke can be worse. Poison ivy may seem difficult to eliminate from your property, but you can do it with consistent, careful and conscientious effort. For more information, please contact me: Will Yliniemi, Hubbard/Becker County Extension Educator at 1-218-732-3391, 1-218-846-7328 or by cell at 1-218-252-1042, or by email at ylini003@umn.edu

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