Entomology & Plant Pathology Weekly Review, April 24
Indiana Department of Natural Resources sent this bulletin at 04/24/2024 07:58 AM EDT
Weekly Review for April 24, 2024
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.
I wanted to share a couple photos of some Graham Blandy boxwood that I found at a nursery dealer. These plants have suffered some kind of injury. I suspect likely winter injury which could be from environmental conditions such as frost injury, harsh drying winter winds, snow and ice breakage, or generally dry conditions in the pots.
Samples from the symptomatic tissue were tested and Volutella blight (Pseudonectria buxi) was confirmed. This stress-related fungal pathogen enters through damaged plant tissue. All species and cultivars of boxwood are susceptible. Leaves turn light green and then straw colored and remain attached to the branches for a long period after leaf death. The retention of the dying/dead leaves is the opposite of what is seen with the boxwood blight fungus (Calonectria pseudonaviculata).
Boxwood blight will result in a rapid defoliation of the plant. The close-up photo of the damaged stem shows the salmon-colored sporulation (circled in blue) of the fungus.
I have been checking in with a number of nurseries over the last week or so. Mostly I have seen the typical traces of aphids, thrips, and spider mites with a bit of cold injury thrown in.
Most of the time these early insect infestations can be linked back to greenhouse sanitation (lingering weed issues in the houses) or infested material coming into the houses. I know this is a busy time but take this as a reminder that doing the little things like weed control and inspecting new material can save you a lot of time later.
I also ran across a case of pretty significant animal damage. According to the grower, rabbits had gotten into the poly house and caused thousands of dollars in plant losses. Aside from exclusion, I don’t know of any other proven techniques to dissuade rabbits. Any suggestions?
