Spring Dormant Herbicide Treatments for Alfalfa

Spring Dormant Herbicide Treatments for Alfalfa

Mike Rankin
Crops and Soils Agent
University of Wisconsin - Extension

Spring dormant herbicide applications on alfalfa are not common but can make sense in the right circumstance. Both Sencor and Velpar can be used to control dandelions in established alfalfa stands before alfalfa “greens-up” in the spring. However, applications can be relatively expensive.

According to Jerry Doll, UW Extension Weed Specialist, the conditions necessary to use one of these products are as follows:

· Be sure the alfalfa is alive; dig a few plants and look for evidence of live buds and healthy roots. There must be at least 4 to 5 healthy alfalfa plants per square foot to justify the use of these herbicides.

· Alfalfa should be in the "pregreenup" or dormant condition to apply Sencor as a spray. Velpar can be sprayed if there is no more than 2 inches of new growth. If these products are impregnated onto dry fertilizer, application can be made when the alfalfa has up to 3 inches of new growth.

· The snow must be gone and the ground must not be frozen when the application is made.

· Do not treat fields seeded last year; the alfalfa needs another season to become well established and thus tolerate the use of the herbicides.

· Do not treat fields if winter injury or other serious stresses are affecting alfalfa's vigor and health.

· Plan to harvest treated fields for at least two years following a single application. This will help ensure full return on the relatively high priced investment.

Weed-free forage does not increase crop yields. The payoff must come through improved forage quality.

“The only thing wrong with dandelions in alfalfa is that they have yellow flowers. If they had green flowers, nobody would worry about them.

Gordon Harvey, former UW Weed Specialist

For more information contact Mike Rankin