Time To Scout For Insects In Soybean Fields
LAMAR, MO.
Jill Scheidt, agronomy specialist with University of Missouri Extension, scouted fields Sept. 16 near Arcola in Dade County and north of the junction of Hwy. 126 and Hwy. 43 in Barton County.
Scheidt observed soybeans in the beginning seed to seed development stages. She observed grasshopper foliage feeding on most plants, but not at high enough rates to cause concern.
“Foliage feeding from insects should become less of a concern as we progress into fall,” said Scheidt.
Scheidt says the following tips can help a farmer identify which insect is feeding on soybean foliage. Grasshopper feeding appears as large, jagged holes. Bean leaf beetle feeding appears as small circular holes. Blister beetles feed between the main veins.
The defoliation threshold in soybeans for any foliage feeding insect is 20 percent defoliation during and after bloom.
Scheidt observed a few green stinkbugs below the threshold level of one green stinkbug per foot of row. “Stinkbugs are usually found on the edges of the fields and cause delayed maturity of plants, which can make harvest difficult,” said Scheidt.
Scheidt did not see pod worms or pods damaged by pod worm feeding. “Pod worms need to be scouted for weekly once soybeans bloom until seeds begin to change color. Second crop and late planted soybeans are especially at risk for pod worm damage,” said Scheidt.
The threshold for pod worms in soybeans are one pod worm per foot of row or when five percent of pods are damaged. “The development of a fungal pathogen, Nomuraea rileyi, that is the main biological control for pod worms may have occurred due to all the wet weather and may be the reason that very few pod worms have been seen this year,” said Scheidt. ∆