Stink bugs are a major insect pest of soybeans in the Midsouth. The stink bug complex (p. 3) in the southern US is primarily composed of the green stink bug, the southern green stink bug, and the brown stink bug.

Stink bugs damage soybean by penetrating the pods with their piercing-sucking mouth parts and extracting nutrients from the developing seed. This feeding on seed can result in yield loss and dockage for damaged seed if stink bug numbers exceed the threshold for their control.

The mid to late growing season in the Midsouth is usually accompanied by warm temperatures, high humidity, and prolonged dew periods. When stink bug feeding coincides with these weather conditions as is often the case during soybean reproductive development, injured seed are left susceptible to infection by the fungi that are related to seed decay. The primary pathogen associated with this seed decay is Phomopsis longicolla, which gives rise to the common seed decay condition referred to as PSD. PSD is especially prevalent in the midsouthern US.

A 2013 M.Sc. Thesis published by Mr. Joshua Jones (Advisors Drs. Fred Musser and Angus Catchot) at Mississippi State University presents research results that provide insight into potential relationships between stink bugs and PSD that can exacerbate the PSD condition. Major points from that thesis follow.

• Data from laboratory experiments indicated that stink bugs are capable of transporting Phomopsis longicolla between two points.


• Data from cage studies indicated that soybean pods and seed with damage similar to that caused by stink bug feeding were more likely to be infested by fungi compared to undamaged seed.


• Limited data from a one-year study indicated a propensity for greater yield loss when both stink bugs and Phomopsis longicolla were present compared to the combined yield loss when each was present separately.


• Surveys of commercial soybean fields determined that soybean seed that had stink bug damage had a greater likelihood of being infected by seed decay fungi than did undamaged seed, and that stink bug-damaged seed weighed less that did undamaged seed. Thus, loss of both seed weight and seed quality may be greater if stink bugs are allowed to persist and create avenues to fungal infection of the seed.

The above limited data indicate that fungal infections of and subsequent disease incidence in soybean seed may be reduced if stink bug feeding is minimized. Therefore, management practices that prevent or reduce stink bug infestations could result in lowered seed quality losses that are due to seed decay fungi.

Composed by Larry G. Heatherly, Sept. 2015, larryheatherly@bellsouth.net