Indiana Department of Natural Resources sent this bulletin at 07/08/2020 10:10 AM EDT
Weekly Review for July 8, 2020
This informal report by the Division of Entomology and Plant Pathology is designed to update the Nursery and Greenhouse industry of insect and disease pests the Division has been encountering on a week to week basis and as a way to give a “heads up” of things to be on the lookout for. Comments and questions about this report are welcome and can be sent to your respective Inspector.
This week I found some more Japanese maple scale. This particular location had a quite extensive infestation and was actually causing some dieback in some instances. I found zelkova, red maple, service berry and Canada red cherry to be infested. Herbicide injury was another theme this week and was found on oaks, maples, locust and dawn redwoods. Finally, I also found some locust pod gall midge. The gall midge feed on leaves and induce the plant to form a small pod from part or all of the leaf. After the larvae pupate and leave the gall the leaf/pod dies and drops from the tree. Heavy infestations can cause localized dieback and can lessen the aesthetic value of the plant.
Ren Hall (Nursery Inspector & Compliance Officer) - RHall@dnr.IN.gov
This weekend I got a macro lens attachment for my cell phone and had some fun taking pictures of insects around my yard and garden. It cost about $20, and the improvement in picture quality when taking photos of tiny insects is substantial. Here are a few things I spotted:
Lacewing larvae are predators of other insects, and many gardeners buy them to use as natural pest control. I spotted several on cilantro flowers, hunting small insects, and was able to get a great photo using my new lens. Wheelbugs are another insect I’m always happy to see in my garden because they are great predators, too. I always find some bright yellow aphids on my milkweed plants every year. I can usually tell when they’re starting to be a problem when the plants are suddenly covered with ants feasting on the honeydew. Potato leafhoppers have been causing a lot of damage the past few weeks on a wide variety of plants in my yard. I have seen many of the insects themselves, as well as the feeding damage, which you can see on the photos I took on calendula. The leaves show the tiny puncture wounds dotting the leaves where the piercing-sucking mouthparts have penetrated, and the yellowing on the edge of the leaves is characteristic of “hopper burn”. I also found thrips on black-eyed Susan flowers that were so small I could barely see them with the naked eye but I was able to get a decent photo with the macro lens, and many of these cute little planthoppers with fuzzy rear-ends.
A lot of what we see while doing inspections isn’t necessarily gravely injurious to its host and may require specific species of plants for its very survival. Here a Tetraopes tetrophthalmus (red milkweed beetles) is resting in a bit of shade after having a good munch.
I’ve been called by homeowners a few times over the last couple of years concerning declining white pine stands. I went on just such a visit this week, and I saw exactly what I expected to see – a row of older (35- to 40-year old) trees spaced 8 feet apart. A few of these trees were dying back. While it was easy to find engraver beetle finishing off these stressed trees, the real problem is probably a combination of tight growing conditions (leading to crowding and branch dieback) and subpar soils. While Eastern white pine is probably the best Pinus we have for northern Indiana, planting them in our heavy clay soils usually leads to a limited life in the landscape.
Sometimes the unusual catches the eye — like a mottled tortoise beetle in a greenhouse. It would be far more likely found on milkweed or morning glory than the sweet potato vine I found it on. Tortoise beetles are not uncommon, but rarely do much harm to their hosts.
Finally, I’m seeing more four-lined plant bug damage on various species as the summer progresses.
