(Kacey Birchmier) – Japanese beetles are back. Illinois reports indicate Japanese beetle populations are very high in some locations, says Kelly Estes, state survey coordinator for the Illinois Cooperative Agricultural Pest Survey Program, in the University of Illinois Bulletin.
“With corn starting to tassel and getting close to tassel, it’s important to remember, even though densities may appear to be extremely high, the average density of beetles across the field may be below levels of economic concern,” says Estes.
An insecticidal treatment should be considered during silking if:
- There are 3 or more beetles per ear.
- Silks have been clipped to less than ½ inch.
- Pollination is less than 50% complete.
When it’s time to scout, remember there are usually clusters of Japanese beetles near field edges. If those are the only locations sampled, it will skew the numbers, warns Estes.
“It’s important to scout flowering soybean fields for the presence of Japanese beetles,” says Estes. “Insecticidal treatments should be considered when defoliation reaches 30% before bloom and 20% between bloom and pod fill.”
Get out there and scout during #grow17 for this pest! Below are images of Japanese beetles on crops across the Midwest.
Japanese beetles? Did someone say Japanese beetles??!! Very isolated pockets of beetle activity. pic.twitter.com/z2snCBEANF
— Brewer Fert. & Farms (@BrewerFert) 11 Juli 2017