According to University of California IPM specialist Pete Goodell, there are three main factors that should be considered in managing lygus in cotton:
1. What is the source?
- Is it a strong source, such as safflower or seed alfalfa, which produce large numbers of lygus as the crop is prepared for harvest?
- Is it alfalfa hay, which can mitigate the movement of the pest if habitat is preserved?
- Is it weaker sources, like tomato or other poorer hosts, which produce far fewer?
- How far from the source is the field?
- The greater the distance from the source, the less the threat. Even the strongest sources have a limited sphere of influence, perhaps no greater than 2 miles.
2. How many lygus are in the field and how much threat do they present?
It is essential to frequently monitor and record cotton fruit retention as well as the population density of lygus. Both are critical for making the best decision. Small numbers of lygus in a field with poor retention is a greater threat than a larger population in a well-fruiting field. Remember, the cotton integrates all stress, bugs or weather, and reflects that in current fruiting conditions.
3. What to use to control Lygus?
Chose your material carefully to limit resistance pressure on the pest target. Understand IRAC mode of action labels and utilize rotation of active ingredients. Start with the most selective products to preserve your valuable inventory of natural enemies and avoid secondary outbreaks of aphids, mites or whiteflies. Move to more broad-spectrum insecticides later in the season.
“Checking your fields is an investment, not an expense,” says Goodell.