Alfalfa Weevil Management Guidelines

Authors: Christian Krupke and John Obermeyer

Pest managers should now be scouting their alfalfa for leaf feeding from weevil larvae. This pest is often overlooked during the early spring planting season.

Producers can manage this pest most effectively by utilizing heat unit accumulations data (base 48°F) to determine when sampling should begin and when an action should be taken, The management guidelines listed below should be used to determine when alfalfa weevil should be controlled in southern Indiana. Refer to the following map for alfalfa weevil development in your area.

Alfalfa Weevil Management Guidelines Southern Indiana

Heat Units % Tip Feeding Advisory
200 Begin sampling. South facing sandy soils should be monitored earlier.
300 25 Re-evaluate in 7-10 days using the appropriate HU or treat immediately with a residual insecticide if 3 or more larvae are noted per stem and % tip feeding is above 50%
400 50 Treat immediately with a residual insecticide.
500 75 Treat immediately.
600 75+ If cutting delayed more than 5 days, treat immediately.
750 If harvested or harvesting shortly, return to the field in 4-5 days after cutting and spray if 1) there is no regrowth and weevil larvae are present OR 2) feeding damage is apparent on 50% of the stubble and weevil larvae are present.

Alfalfa weevil tip feeding.

It is the policy of the Purdue University that all persons have equal opportunity and access to its educational programs, services, activities, and facilities without regard to race, religion, color, sex, age, national origin or ancestry, marital status, parental status, sexual orientation, disability or status as a veteran. Purdue is an Affirmative Action Institution. This material may be available in alternative formats. 1-888-EXT-INFO Disclaimer: Reference to products in this publication is not intended to be an endorsement to the exclusion of others which may have similar uses. Any person using products listed in this publication assumes full responsibility for their use in accordance with current directions of the manufacturer.
Pest&Crop newsletter - Department of Entomology Purdue University 901 W. State St. West Lafayette, IN 47907

© 2018 Purdue University | An equal access/equal opportunity university | Copyright Complaints | Maintained by Pest&Crop newsletter

If you have trouble accessing this page because of a disability, please contact Pest&Crop newsletter at luck@purdue.edu.