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Insect infestations can threaten alfalfa stands.

Agronomy Bulletin 92 ─ Potato Leafhopper

Nymph (left) and adult (right) potato leafhoppers continue to be a problem for Midwest alfalfa growers.

Situation

In Midwest alfalfa fields, potato leafhoppers can cause significant problems for alfalfa growers by reducing yield, quality and stand longevity. Scouting alfalfa stands for these pests is crucial to alleviating future headaches.

Factors to Consider

  • Pest identification
  • Life cycle
  • Cutting schedule
  • Treatment

Action Plan

  1. Identify the pest. Leafhopper nymphs are yellow in color and do not have wings. Adult potato leafhoppers are about 1/8 inch long with yellow-green wings. Both adults and nymphs are wedge-shaped. Leafhopper eggs are clear and can be found in the alfalfa stem.
  2. Understand the life cycle. Potato leafhoppers live year-round in the Gulf Coast region. Each spring, weather fronts carry adult leafhoppers north. Potato leafhoppers appear in alfalfa fields when the first cutting of alfalfa is nearing harvest.
  3. Scout for leafhoppers. Most leafhopper damage occurs mid-June to mid-August. Monitor fields weekly following the first cutting until the end of the season. Look for yellow triangles on the leaves and stunted plants. Alfalfa also may turn a reddish or purplish color as a result of an infestation.
  4. Evaluate harvest schedule. If leafhopper populations are above economic thresholds, a timely harvest will reduce populations. Harvesting alfalfa can eliminate leafhopper eggs already laid in stems, suppress the nymph population and displace adults.
  5. Consider insecticide treatment. If a potato leafhopper population has reached the economic threshold, an insecticide treatment may be warranted. Timely application of foliar insecticide treatments to reduce potato leafhopper activity will optimize alfalfa yields.

Summary

Optimize alfalfa yields by accurately assessing potato leafhopper infestations and taking appropriate action. For more information, contact your local Mycogen Seeds customer agronomist or trusted agronomic adviser.

Published on Wednesday, July 31, 2013