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Manage Lygus by Managing Nearby Alfalfa

As a preferred host, alfalfa hay can be managed to minimize movement of lygus into cotton by staggering cuttings to preserve habitat. Leaving small uncut strips at each harvest is very valuable in limiting the movement of lygus into neighboring cotton. When interplanted with cotton, alfalfa will attract lygus bugs away from the cotton crop and prevent massive dispersal into cotton fields. Alfalfa strips also serve as reservoirs for predators and parasites that will eventually move into cotton and help suppress spider mites, lygus, and worm pests.

Overall strategy:

• Maintain nearby alfalfa fields in a succulent condition.
• Avoid cutting all alfalfa fields in an area within a short time period. Leave an uncut strip or check at each cutting along the border between alfalfa and cotton to slow lygus migration.
• If lygus populations get very high, uncut strips of alfalfa may be treated with an insecticide if needed, but sprays should be avoided where possible to protect beneficials.

Where strips of alfalfa grow within or along edges of the cotton field:

• Plant a sufficient area with alfalfa, manage for succulent growth, and alternate cutting half of each strip every two weeks.
• Cut back with a stalk cutter. In a 28-day cycle, many lygus eggs will be inside the cut stems and will die as the stems desiccate.

Related information:

• Lygus bug pest management guideline
• Managing alfalfa for lygus control: California Cotton Production web site