Other changes in insect control recommendations include:

• Soybeans: Recommended termination of insecticides for defoliating insects has been changed from R7 to R6.5. “Data we collected on defoliation in 2009-10 show less yield loss during R6,” Musser says. “By terminating at R6.5, you won’t have reached economic injury level before beans reach R7 stage.

• Bean leaf beetles: “The old threshold was 20% defoliation during reproductive stages or 2 insects per sweep and we were triggering a lot of unnecessary sprays. We’ve changed it to 20 percent defoliation or 50% plants with pod feeding and eliminated the 2 insect/sweep threshold.”

• Stink bugs: Damage at R3 and R4 can cause “pretty big yield losses from relatively low densities of stink bugs,” Musser says, “but at R6-R7, the only loss is quality. In most years in most situations, they don’t do enough quality damage to cause economic loss. So, we’ve have changed our late season R6 threshold to 20 stink bugs per 25 sweeps.”

• Three-cornered alfalfa hopper: “Our threshold is 2 insects per sweep during reproductive stage. Later in the season, it’s still 2 per sweep, but our ongoing research suggests it could be much higher than 2. In cage studies by a graduate student,” Musser says, “we were getting girdling, but we’ve not been able to document yield loss, even as high as 8 adult insects per sweep.

“Termination has been moved back to R6 instead of R7, because they’re just not doing that much damage at that point.”


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