In-Season Insect and Disease Control


Aphids on alfalfa stemAphids (spotted, blue, pea, cowpea)
Count aphids on at least 20 stems or take at least 20 sweeps per field, and average the number of aphids per stem or sweep.
Midwest/East threshold: Treat pea aphids when numbers exceed 100 per sweep. 

West/Southwest threshold: Treat pea aphids when there are 50 per stem and alfalfa is less than 10 inches tall; when there are 80 per stem and alfalfa is 10 to 20 inches tall; and when there are 100 per stem and alfalfa is more than 20 inches tall.

Treat blue alfalfa aphids when there are 12 per stem and alfalfa is less than 10 inches tall, and when there are 50 per stem and alfalfa is more than 10 inches tall. Aphids are a problem mainly in dry periods. During cool and/or wet periods, aphids are controlled by other predators, parasites and diseases. The most significant predator is the ladybird beetle.

Alfalfa weevil on damaged alfalfa leafAlfalfa weevil

Threshold: Treat if 30 to 40 percent of plants show any feeding. First crop and early second crop regrowth must be monitored closely.

Adult potato leaf hopper on alfalfa plantPotato leafhopper​

Threshold: One adult in 10 sweeps. The main concern is in the Midwest and East in new seeded alfalfa, and established second to fourth crop regrowth. The highest pressure is typically late June through August.



  • High-performing WinField® products can help control a variety of troublesome pests. Contact your local WinField representative or visit for more information. Always read and follow label directions.

  • Contains permethrin for broad-spectrum control of insects in alfalfa. Ideal for potato leafhopper. Readily mixes with water and most fluid fertilizers.

  • Contains lambda-cyhalothrin for broad spectrum control of insects in alfalfa, including aphids. Combines peak performance with easy handling.

  • Contains chlorpyrifos for broad-spectrum control of insects in alfalfa. Especially effective in controlling weevil intrusions on alfalfa.


Anthracnose damage on alfalfa stemFoliar leaf diseases: Monitor plant health for lepto leaf spot, common leaf spot and spring black stem leaf spot. These diseases cause leaf loss and reduce yield and quality.

Apply BASF Headline® fungicide to control leaf spot, multiple races of Anthracnose, mildew and other diseases. Increased leaf retention and higher plant health leads to improved quality and yield potential.

Map of Anthracnose susceptibility in the United States
Anthracnose is a severe stem and crown disease that causes defoliation. Multiple races can be present in late season.