South Carolina Corn: Dealing with Stink Bugs in Early Fields

There have been numerous calls about stink bugs being an issue on early corn. I contacted my colleague, Dr. Francis Reay-Jones, located at the Pee Dee REC in Florence, who covers insects important in corn, and here’s his take on the situation:

Stink bugs can sometimes be economic pests at the seedling stage, and later, particularly during ear elongation stages. The data though are very limited, since it’s challenging to do trials with stink bugs in corn. So I’m relying on the limited data available, mainly from NCSU.

Feeding at the seedling stage can lead to tillering, malformed plants, and sometimes plant death. Damage can occur particularly from V3 to V6 – after that, the growing point is above the soil surface and stink bug injury generally will not be significant in most cases until ear elongation (V12 to VT). From V3 to V6, consider a 10% plants infested with stink bugs as a threshold.

This does not happen too frequently, as there are other hosts in the landscape such as wheat which are preferred. When wheat dries down, stink bugs can move into adjacent corn, but that often is not until after V6. So significant economic infestations of stink bugs can occur in seedling corn, but this is not common in my experience.

From V12 to VT, a threshold of 25% plants infested can be used. Infestations at this stage are much more common. Stink bugs will feed through the stem on the developing ear – this can cause significant injury and yield loss, since the whole ear can be malformed. This is the stage when most applications in South Carolina will need to be made, though in many cases, a corn crop will not need to be treated.

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2017 was a bad year for stink bugs in corn, and we did have problems from stink bug feeding at this time.

Once tassels appear, most of the damage to the ear has already occurred. This is why tank mixing a fungicide with an insecticide is often not effective, since the timing is usually not optimal for both at the same time.

From R1 to R4, use a threshold of 50% plants infested. At this point, feeding occurs on individual kernels – so impact on yield is much less than a completely malformed ear. A 50% infestation at this point is rare.

The brown stink bug is the main species we see in corn. Bifenthrin is the best product we have available. Control is very difficult because stink bugs are fairly protected by the foliage. Need a very good aerial applicator to even have a chance at decent control because of the small amount of water used.

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