Brown marmorated stink bug and stay-green
Photo by Jeff GraybillFigure 1. A stay-green condition resulting from stink bugs on a field edge. Stink bugs populations in corn and soybean fields are decreasing steadily as the weather cools. This is good news for growers in southern Pennsylvania who saw large stink bug infestations earlier in the year because it will end the risk of damage from stink bugs. A notable downside to stink bugs leaving fields is that more and more are going to start showing up in homes and outbuildings as they seek a place to spend the winter.
As stink bugs leave and soybeans continue to dry down, some of the influence of their feeding is becoming evident. Stink bug feeding shrivels seeds and so causes flat pods. A more recognizable symptom of heavy stink bug feeding is a condition often referred to as “stay green” (Fig. 1). This condition occurs when fed-upon plants stay green longer, apparently in an attempt to compensate for the feeding damage they received. This stay-green syndrome can be problematic because different parts of the field may senesce at different rates and the entire field will not be ready for harvest at the same time. It is useful to recognize this condition in fields that had many stink bugs so that other causes are not blamed. Growers will have to use their experience to determine how best to harvest these fields.