Indiana Department of Natural Resources sent this bulletin at 08/16/2023 07:35 AM EDT
Weekly Review for August 16, 2023
This informal report by the Division of Entomology & Plant Pathology is a commentary on insects, diseases, and curiosities division staff encounter on a week-to-week basis. Comments and questions about this report are welcome and can be sent to your respective inspector.
Here are a few photos of interesting finds this week.
Will Drews (Nursery Inspector & Compliance Officer) - WDrews@dnr.IN.gov
This is my first weekly review as a new nursery inspector with the division. I have been primarily focused on the state kudzu control program right off the bat, but I have been also working with several of my nurseries on their issues and inspections.
Last week, I noticed a lot of missing limbs and branches on ‘Purple Robe’ black locust trees at a nursery in Monroe County. At first glance it looked like heavy wind damage. However, none of the surrounding trees (of different species) showed similar signs. After a closer examination, I noticed some canker-like growths on the trunks and limbs as well as small sawdust deposits and galleries. These indicators plus the localized damage to just black locust trees led me to believe this is possibly the work of the locust borer (Megacyllene robiniae), a beetle pest that specifically targets black locust trees.
Locust borers lay their eggs in late summer/fall. The larvae hatch and bore into the inner bark to hibernate over winter. In spring, the larvae start to bore deep into the trees. Around July, the larvae pupate and emerge out of their tunneling holes. The damage they cause will not often kill healthy, mature black locust trees. However, the damage they cause to young trees can often cause weakened wood that easily splits in the wind, leading to trees with poor form.
