Indiana Department of Natural Resources sent this bulletin at 06/21/2023 07:20 AM EDT
Weekly Review for June 21, 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.
First, due to scheduling conflicts, there will be no weekly review next week. We’ll be back with you around July 6.
By the time you read this, we should be wrapping up our spongy moth mating disruption treatments in Starke, Marshall, Kosciusko, and Fulton counties. The treatments are planned for June 19-21 if the weather holds out.
I keep seeing a lot of aphids. Spirea is starting to get hit hard while oaks, birch, and crabapples are also a good place to look for them. The lack of rainfall the last couple of weeks allowed spider mites to get a good foothold. Keep checking for them the next couple of weeks. Dry conditions and heavy mite populations is a recipe for heavy mite damage.
I found a single ‘blue muffin’ arrowwood viburnum with wilting shoot tips, which usually come from simple over or under watering. Pulling the container off revealed dark, rotting roots at the bottom. While it may have been too wet, I would not consider this plant overwatered at the time I saw it. I have a site history of positive Phytophthora tests and a positive identification of P. cinnamomi from a couple of years ago. Combined with overirrigation during our dry spell, I think P. cinnamomi is going to be the culprit again.
Finally, I found one that takes me back to my agronomy days: crown rust. While it does little damage on the secondary host (‘fineline’ buckthorn, in this case) it is one of the most damaging diseases of oat and barley crops. Specific varieties of crown rust will also attack ryegrass and fescue lawns.
To those of you who garden and are looking to plant something for bees or other pollinators, I suggest using buckwheat as a cover crop in your garden. Buckwheat is a warm-season annual grain that grows extremely fast. It will bloom in as little as 60 days, attracting honeybees as well as a wide variety of native pollinators, including bumblebees, bee flies, solider beetles, and hover flies. It makes an excellent weed-suppressing cover crop, growing to approximately 3 feet, and breaks down quickly after it is terminated. It will die with the first light frost or can be easily controlled by mowing, crimping, tilling, or herbicide. Buckwheat will also readily reseed if you let it go past flowering, or you can harvest the seed for making flour.
Zimmerman pine moth leaves distinct pitch masses on the trunk of pine trees. This species attacks nearly all species of pines and will occasionally feast on spruces and firs. The pitch masses, as seen in the photo, are often at the base of a branch or at the branch whorl. Reddish frass is often mixed in with clump of pitch. Right now, there’s a larva underneath that mass of goo. There is a single generation per year. Adults will emerge in the coming weeks. Treatment is best done in early April into May, but right now, if the infestation is smaller, you can hand-cut the pitch mass to remove the larva. If a tree is heavily infested, this method of control isn’t a viable option.
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
Finally, we got some rain in my region. I received 1.3 inches on June 11 and 0.31 inches on June 7. Many plants are not happy, so I hope this helps. I found boxwood mite on my property for the first time this week. I found leafminer damage on columbine and daylilies. The damage caused by leafmining insects on these plants is usually cosmetic; however, I have seen some cases in which columbine leafminer was bad enough to give the foliage an overall white appearance. I have also seem spittle bugs feeding on herbaceous plants. Look for foamy, spit-like material on infested stems. This is another pest that is typically not a serious problem unless it becomes abundant; however, I have never seen a case where it was necessary to treat spittle bugs.
During the past week I encountered a pest that I have never seen before. It was the phlox plant bug, Lopidea davisi. I found this pest at two locations in Monroe County, one in Unionville and the other in the city of Bloomington. In both cases the damage from this pest was very noticeable and significantly affecting plant health. Plants had a whitish appearance from heavy stippling caused by plant bug feeding. The insect is orange and black. It looks somewhat similar to the yucca plant bug, but it is a bit larger. Apparently, this insect will feed on native phlox but can also move to cultivated varieties of phlox. This pest has been reported to cause serious injury to phlox in other states.
I have not observed many disease issues during the last several weeks. It has been so dry with low relative humidity levels, seemingly delaying the onset of many fungal issues; however, there was one exception. Leaf spot was very heavy on iris at multiple locations in Monroe County. My guess is that the wet first week of May allowed for infection of many irises, and the disease continued to develop. Look for spotting that coalesces to cause leaf necrosis.
Finally, I found a large moth on the outside of the gas station in Ellettsville while fueling my vehicle. Of course, I had to drag the store clerk outside to show her. Other people stopped by as well. It was a large moth that called a Polyphemus moth. It looks a bit similar to a Cecropia moth, which is in the same family, but the eye spots were a bit different.
