The 2019-20 winter season has delivered limited amounts of cold weather in Louisiana. As a result, the likelihood of stink bug infestations in soybean fields may increase in 2020.
Temperatures at 32 degrees for a week or 23 degrees over a four- to seven-hour period are required to reduce redbanded stink bug (RBSB) overwintering populations.
This winter has seen very few hours at those temperatures. During unusually cold winters – such as in 2010, 2014 and 2018 – RBSB did not survive, and populations infesting soybean in those growing seasons were reduced. After a warmer winter, higher populations of RBSB may successfully overwinter.
When they do overwinter, RBSB survive by feeding on alternative hosts, such as crimson clover and other legumes. There are often mixes in cover crops, and timely burndown is key to reducing stink bug food resources.
Limited amounts of cold weather greatly increase the growth and development of alternative hosts, providing abundant food sources for RBSBs, leading to large increases in populations in early spring.
When They Do Survive
If stink bugs are present in the field during early vegetative growth, they may feed on leaves in the lower canopy. Injury from v-stage feeding is minimal and soybean plants will often grow out of any injury sustained early season.
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If large early-season populations of RBSB are left unchecked, they can potentially increase to economically damaging levels sooner and will be harder to control as the canopy closes.
RBSBs are an annual threat to Louisiana soybeans, and producers may experience larger-than-normal RBSB populations this year.
What To Do
Managing RBSBs requires an integrated approach. Selecting cover crops that do not include legumes, such as crimson clover and eliminating alternative legume hosts surrounding field edges may help reduce early-season population numbers.
Planting soybeans early within the LSU AgCenter’s recommended planting window also may help lessen the number of later season stink bug applications. Utilizing thresholds and rotating insecticide modes of action help mitigate resistance and aid in application decision making.
The LSU AgCenter threshold for RBSB is four 4 per 25 sweeps. Producers should budget three to five applications for RBSB, with late-planted varieties in southern parishes potentially requiring more.