Indiana Department of Natural Resources sent this bulletin at 05/12/2020 09:32 AM EDT
Weekly Review for May 12, 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.
Our planned Gypsy Moth Btk treatments for Westville and Huntington have been pushed back until the week of May 18 due to weather and lack of leaf expansion on oaks. Frequent updates are posted on Twitter @INdnrinvasive.
I guess we should say something about “murder hornets”. In a nutshell, Asian giant hornets have never been found anywhere in the Midwest. A handful were found in Washington state and British Columbia in late 2019. Entomologists are not clear if this insect managed to overwinter in North America, so they are asking folks in the Pacific Northwest to keep an eye out for this critter. For more information, check out the Purdue Landscape Report article.
With the cold snap we had over the weekend, I figure there will be plenty of frost injury to be seen for the rest of this year. This was the first time I ever lost a tomato inside a wall-of-water! With the continued shifting weather, I want to remind everyone to be mindful of the temperature inside greenhouses and under plant covers. It is really easy to “batten down the hatches” at night, then forget to open things up in the morning. On a sunny day (if we ever get one), it can quickly get to 70 or 80 degrees under a cover.
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
I am seeing a few Eastern tent caterpillars in my region, but the pest season continues to be off to a slow start. Boxwood leafminer adults have emerged and were swarming around my boxwoods Saturday afternoon. Look for small, orange, gnat like insects. These small insects will lay eggs in leaf tissue to start next year’s generation. I had a great deal of freeze damage this year, and I am not sure if this will affect next year’s population level because there may be less new growth available for easy egg laying. During an inspection I saw damage from bronze birch borer on Youngi weeping birch. Look for D-shaped exit holes and bumps in the bark from larval feeding. This particular cultivar of birch is highly susceptible to bronze birch borer.
On the same tree, I found a twice stabbed lady beetle. This is a small black lady beetle with two red dots on its back. It is a beneficial insect that typically feeds on scales. In southeast Brown County I found sawfly feeding injury on white pine. However, the sawfly larvae were no longer active. The feeding damage may have been caused by the introduced pine sawfly. I very rarely see pine sawflies in my region. Occasionally, I see European pine sawfly on hard pines in spring and red headed pine sawfly on hard pines in summer, but they are not that common in my part of the state. When I lived in Pennsylvania, you could always count on European pine sawfly to cause a problems on mugo pines every spring.
I am continuing to see black spot and powdery mildew on roses shipped in from out of state suppliers. So far I have not observed any downy mildew on Knock Out but I did get confirmation of downy mildew on Arapaho blackberries. I also found canker and dieback on red twig dogwood. These plants are attractive in the wintertime but often suffer from this problem. Look for blackening stems on both red and yellow twig dogwoods. Laboratory identification is necessary to determine exactly which pathogen is causing the canker symptoms. Pruning out infected branches can help manage the problem but if the infection occurs at the base of the plant, it can kill the entire plant. Last week I also found a heavy amount of sooty mold on one individual branch of white pine. I did not see any signs of scale insects that could be causing the production of honeydew followed by sooty mold. It was a cool, wet day and I did not see any serious issues with the health of the tree. I found it interesting because I had never seen sooty mold growth that large before. The forecast is for warmer and wet weather toward the end of the week. We may start to see more disease issues and finally maybe some insect pests.
