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

Trade and the Farm Economy-Two Charts to Watch in 2020
1/28/2020

Before the ink dried on the newly signed Phase 1 trade agreement, dozens of articles and Twitter threads emerged with clever insights into the nuances and subtleties of the agreement. Most debates focused on the base level China agree to buy up from, and the relevant commodities and products. Stepping back from the details, this […]

Soybeans Need Good News
1/28/2020

Soybean futures prices fell again last week on reports of a coronavirus outbreak rattling the Chinese economy and the prospects of a huge Brazilian crop.  A double hit associated with increased production from our main competitor and a potential drop in Chinese demand appears set to drive prices lower in the near term.  If present […]

Costs of Corn and Soybean Production
1/28/2020

In a recent update from Iowa State University (ISU) Extension (“Estimating costs of crop production vital for 2020 farm businesses“), Alejandro Plastina explained that, “Thin profit margins in corn and soybean production have become the norm over the past five years, increasing the need for proper budgeting and marketing strategies among crop producers.” The ISU update noted that, “On average, the total […]

Your browser is out-of-date!

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