A friend of mine, Owen Taylor, who maintains AgFax thought that it was really interesting that more rain has fallen across North Carolina in the past month than the yearly total of where I was raised. Yes, it truly is like Mars compared to the swamp that is now the state of North Carolina. Jack Bacheler effectively covered the impact of this on cotton insects (article here). I received one call where boll retention was around 80% from the cloudy wet weather. This was not due to plant bugs and many surrounding fields were 90% retention or better. NCSU cotton agronomist Keith Edmisten maintains that this is a very very rare occurrence in our state. Nonetheless you’ll want to vigilantly scout your fields for plant bugs, since they might move into cotton now or when corn begins to dry down (did I just write dry down?).
I’ve been getting a number of questions on the impact of rain on kudzu bug. In general, rain can impact aphids, spider mites and worm pests by enhancing conditions for diseases that might kill them. Rainy weather creates great conditions for stink bugs. As far as I can tell, the impact is very little on kudzu bugs.
You should be using the one nymph per sweep threshold on all full-season beans at this point, regardless of their height. I am not sure what this season might hold for kudzu bugs in double-cropped beans so we’ll just have to wait and see. If you have early-planted beans, the kudzu bugs will likely be back in August! A spray now will have no impact on the upcoming migration from the next generation.
In the meantime, it would be a good idea to put together an insect management plan for August and September. I suggest using this article on corn earworm as a guide. Think about how you might rotate chemistries and timings to manage kudzu bug without flaring corn earworm and other worms. Pyrethroids are great for killing kudzu bugs, but, if they are sprayed during flowering, they can often make earworm, looper and armyworm problems worse by killing beneficial insects.