IPM Bulletin

Penn State Extension in Franklin County has established a grid of eight trapping sites across the county to attempt to survey populations of black cutworm and true armyworm moths. Both species have now been found in the county; however, black cutworm moths have not been found at threshold levels. True armyworm moths have been found at most sites with the most in the St. Thomas area, which had 10 moths last week. Other sites had two or less. These findings suggest that populations may be heavy in the greater St. Thomas area for true armyworms and special attention should be given when scouting and making recommendations in this area.

One of the most important management considerations when dealing with true armyworm is to make sure in areas where you have cover crops or heavy weed cover that you allow a 2 week period after the plants are dead until you plant. This would lead producers trying to get a timely planting of corn who have yet to spray to use a quick killing herbicide such as gramoxone instead of glyphosate.

Once corn is established scout fields closely, especially where heavy cover was. If you find more than 10 percent of your corn in a given field has an infestation of armyworms treatment is encouraged. Armyworms typically are found hiding in the whorl of corn during the day and their feeding creates a ragged looking leaf. In bad cases the leaves will be fed on until nothing but the mid-rib is left.

More information on this pest can be found online at http://ento.psu.edu/extension/factsheets/armyworm, or by visiting the local extension office. Please share this information with others who may be interested in it. Again it appears that the pressure at this point is limited to the greater St. Thomas area. I will continue to keep you up to date if populations build elsewhere.