Indiana Department of Natural Resources sent this bulletin at 08/20/2019 08:51 AM EDT
Weekly Review for Aug. 20, 2019
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.
Ever notice how the only ladybugs you seem to see these days are the Asian ones? I get kind of excited to see a native ladybug. This one is a twice-stabbed lady beetle I came across last weekend. There’s a really cool “citizen science” project out there called The Lost Ladybug Project. The objective is to locate, photograph, and identify lady bugs across the United States. This project was inspired by the decline of the nine-spotted ladybug across most of its range.
Driving around, I’ve noticed a pretty good bit of fall webworm popping up. Drought damage on trees is fairly noticeable as well, but I hope the three inches of rain we got this weekend will help address that situation.
Spidermites were causing damage on many different kinds of plants this past week. I saw heavy infestations on columbine, anemone, blue lobelia, ‘Autumn Blaze’ maple, bald cypress, honeylocust and English oak. Bagworm was found feeding on columnar hornbeam, bald cypress, Norway spruce and blue spruce. The caterpillars were pretty large so they won’t be feeding for much longer. Oystershell scale was found killing branches on red and ‘Autumn Blaze’ Maple.
Japanese beetles were still causing damage on many plants but the number of beetles I saw were way down from previous weeks. Lacebugs were causing pretty significant damage to Asters and damage was beginning to show up on swamp white and bur oak. Other problems I encountered were various leaf spots on Phlox, Hydrangea, black eyed Susan, honeylocust and maple; powdery mildew on London plane tree and Magnolia; red headed flea beetle on many varieties of Hydrangea as well as Itea; white flies on Helianthus, purple coneflower, blue lobelia and yellow coneflower (Ratibida); leafy bud gall on bur oak; tar spot on red and ‘Autumn Blaze’ maple and Septoria leaf spot on gray and silky dogwood.
Ren Hall (Nursery Inspector & Compliance Officer) - RHall@dnr.IN.gov
On Friday last week I had time for a quick inspection at a small nursery grower in my territory. One issue they were dealing with is aphids, on several different tree species. They carry a lot of river birch and had a pretty heavy infestation on most of the plants, with the associated ants and black sooty mold. Even walking by these trees I would feel a tickle on my arm and look down to see winged aphids hitching a ride. I also saw aphids on white oak – these ones are pretty neat-looking close up. Another find was oystershell scale on maples.
The infestation was pretty severe, causing dieback of small and large branches on many of the trees and previously going unnoticed by the grower. On one half of the nursery almost all the maples were infested, and on the other half all of them were clean. In the infested block, the trees on the outside only had a few scales and no dieback, with severity of infestation increasing the closer to the middle of the block, with several dead or dying trees where the bark was completely smothered with scale insects. It was interesting to see there was a sort of “epicenter” of the infestation and how the insects spread over time.
