True Armyworm and Brown Marmorated Stink Bug Populations Become Noticeable
Posted: July 31, 2012
In the past week, it has become evident that two insect species are becoming more noticeable. I am sure most of you will recall that true armyworms did quite well around Pennsylvania during its first generation with a population outbreak bigger than any other in recent memory (see this previous newsletter article for details: (http://extension.psu.edu/field-crop-news/news/2012/06/june-5#b).
Annually there are three generations of true armyworm in Pennsylvania, but the rule-of-thumb is that the second and third generations are not economically significant. With the enormous first generation population, however, this rule-of-thumb needs to be re-considered. And indeed, now we are hearing reports of second-generation true armyworm infestations in grass hay, corn, and sorghum fields ranging from Mercer County in the west to Centre County. I believe the greatest risk is to central and northern counties where the first generation populations were heaviest, but any area with first generation populations should be aware of the possibility of the second generation being problematic. Scout those fields!
A second pest of note is brown marmorated stink bug. Populations of these guys have been growing slowly in Pennsylvania and have not caused much trouble for field crop growers. Be aware, however, that the summer adults are now active and we are starting to see stink bug populations move from corn fields into soybean fields. Scout soybean fields for stink bugs starting on the edges next corn fields or woods. Many stink bug populations do not progress beyond the edge and if populations are large enough just the edges can be treated. Economic thresholds in soybeans for stink bugs are one bug per foot of row if using visual counts or 2.5 stink bugs per 15 sweeps of a net in narrow-row beans or 3.5 stink bugs per 15 sweeps in wide-row (30”) beans. Remember that we could use your help tracking stink bug populations. If you have populations you would like to report, please visit: http://stinkbug-info.org/ to let us know. Thank you.
- Extension Specialist