Pest Update and 2020 Insect Thresholds

This week we have been finding low numbers on insect pests in cotton, grain sorghum and soybeans.

Cotton ranges from 1/3 grown square to mid-bloom. While most fields are below threshold, we have found a few fields with 30-40 cotton fleahoppers per 100 plants. Continue to monitor for cotton fleahoppers until bloom and treat when they exceed an economic threshold of 15 per 100 plants.

Cotton Bollworm Moth. Photo by Stephen Biles

Blooming cotton has had significant bollworm moth flights this week but so far, egg numbers have been low. Bollworms are important pests and should be monitored by searching for the worms and determining the percent of squares and bolls damaged by worm feeding.  Treat when worms are present and more than 6 percent of squares and bolls are damaged.

Stink bug feeding has been found by checking the internal boll wall for wart growth. So far, we have not found a field with more than 5% evidence of internal feeding. Insecticides may be required to prevent yield loss when more than 20% of 1-inch bolls have wart growth on the inside boll wall. The table shows an accepted economic threshold that changes by the week of bloom.

Grain sorghum fields range from boot to hard dough.  Once a field has reached hard dough, it is relatively safe from insect pests except the potential harvest problems caused by sugarcane aphids. All fields checked have low number of sugarcane aphids so keep an eye on them.

Fields from bloom through soft dough should be checked for stink bugs.  We have found low numbers of rice and brown stink bugs and a few leaf-footed bugs.

Soybean fields we have checked have low numbers of stink bugs and most of them are green, southern green and brown stink bugs with a few red-banded stink bugs.

I have had a few requests of what economic thresholds I am using this summer.  Below is a table with where I am starting.  As always, if you have questions or comments or want to discuss a field, give me a call 361-902-1138. 2020 Economic Thresholds

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