Greenbug plan

GREENBUG

PLAN

• Resistance to Insecticides
• Using the Greenbug Treatment Guide
• Resistant Hybrids

Greenbugs have developed resistance to various insecticides over the years. The proportion of resistant individuals within the population will likely increase with the frequency of insecticide applications, so decisions to spray should always be tempered by concern for potential resistance. Insecticide resistance is independent of greenbug biotypes, which are defined by the reactions of specific sorghum varieties to greenbug feeding.
Resistance management refers to strategies for mitigating the development of resistance in insect populations to ensure the continued efficacy of registered insecticides. This is best accomplished by rotating materials with different modes of action, applying only recommended rates, opting for spot treatments whenever feasible, and by using chemical control only when populations reach economic thresholds.

Using the Greenbug Treatment Guide

• The greenbug treatment guide (in the table below) describes threshold values for various growth stages. For example, an infestation of 10 to 25 greenbugs per plant (based on counts from 25 plants or more) is considered threatening if found early in the season on one-leaf stage plants.

Depending on conditions, the infestation may persist and build, or it may decline. A field should be monitored and treated if populations increase. If the infestation at the one-leaf stage averages 25 to 50 greenbugs per plant, the risk is higher, and serious stand loss is likely. Prompt control would probably be recommended.

Resistant Hybrids

All new sorghum hybrids where once screened for susceptibility to greenbug damage, but this is no longer the case. However, hybrids with various levels of resistance to biotype I are still available. While resistant hybrids are not a perfect or complete solution, they are compatible with all other tactics for greenbug management and should be considered in areas prone to greenbug infestations. Check with local seed suppliers for greenbug resistant hybrids adapted to your area.