Menu

Scout Weekly for Alfalfa Weevils

Scout alfalfa now for alfalfa weevils, says a University of Missouri Extension entomologist. Weevil larvae defoliate plants and reduce the quality and quantity of hay.

Producers in southern Missouri counties should begin scouting fields weekly now and continue through first harvest, says Wayne Bailey. Growers in central and northern counties need to be on the lookout by mid-April. Eggs are hatching in southern and central Missouri fields where alfalfa is growing.

Scout early and often, Bailey says. Look for weevil larvae, which feed on leaf tissue and may completely defoliate the alfalfa plants.

Alfalfa weevil adults lay eggs when temperatures go above 60 degrees for a few days during fall, winter and spring.

Eggs hatch in May and June. Signs of infestation—leaf defoliation and the presence of larvae—show first on warm, south-facing slopes of fields.

Each female lays up to 500 eggs. Each egg produces a small larva that initially hides in, and eats, the growing tips of emerging alfalfa. As larvae grow, they move to plant surfaces to feed on foliage.

Bailey advises growers to prepare to spray or cut hay early. MU Extension research shows that alfalfa weevil larvae numbers drop about 95 percent when sprayed or cut and 90 percent when grazed by cattle.

Green grazing creates risk of bloat in cattle, and cattle can trample wet fields.

Spray fields before harvest. Some fields, especially those in southern Missouri, may require two or more applications of insecticide to control the weevil pest.

Bailey demonstrates techniques for scouting alfalfa for pests in a video at http://youtu.be/65v2YqSBcdg.

He gives spray recommendations at http://ipm.missouri.edu/ipcm/2015/3/Alfalfa-Weevil-Larval-Management-Options-for-2015/.

Source: Wayne C. Bailey, University of Missouri

Recent News

Fall-applied Herbicides-What Goes Around Comes Around
9/22/2020

Fall herbicide treatments have fallen off over the past several years for a couple of reasons, among them the effectiveness of new soybean trait systems for managing marestail, some generally crappy weather in late fall, and efforts to reduce input costs.  We are seeing a resurgence in some weeds, such as dandelion, which respond well […]

New Round of Farm Aid for COVID Losses Announced, and Causes Snag in Congressional Spending Bill
9/22/2020

Andrew Restuccia and Jesse Newman reported in Friday’s Wall Street Journal that, “President Trump unveiled $13 billion in new aid to farmers facing economic harm from the coronavirus pandemic as he aimed to boost support among rural voters at a campaign rally. ‘I’m proud to announce that I’m doing even more to support Wisconsin farmers,’ said Mr. Trump, speaking outside […]

Corn Silage Needs Adequate Moisture to Ferment
9/18/2020

Early season frost is challenging for corn silage producers, according to Karl Hoppe, Extension livestock systems specialist at NDSU’s Carrington Research Extension Center. Frost makes an abrupt end to the corn-growing season. This begins the dry-down period for the corn plants. “Good corn silage fermentation requires adequate moisture to reduce dry-matter loss and spoilage,” Hoppe […]

Your browser is out-of-date!

Update your browser to view this website correctly. Update my browser now