Indiana Department of Natural Resources sent this bulletin at 08/12/2020 08:10 AM EDT
Weekly Review for Aug. 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.
Once again, the USDA has proclaimed August Tree Check Month. This is a great time to look for signs of Asian Longhorned Beetle and other invasive pests. We encourage you to take ten minutes to look at your trees. Signs of ALB include dime-sized exit holes, shallow pits or scars on the bark, and sawdust-like material on the ground or on tree branches.
This is also a good time to consider one of the major movers of invasive pests: firewood. The best strategy is to buy firewood locally. If you are going to move it, burn it all in a short period of time. As a reminder, the firewood rules for DNR properties are still in effect. Visit DontMoveFirewood.org for more guidance and information about firewood regulations in other states.
Ren Hall (Nursery Inspector & Compliance Officer) - RHall@dnr.IN.gov
Here are some pictures I took of anemone with foliar nematodes, found at a box store garden center a couple weeks ago. The symptoms were similar to nematodes I found on weigela last year. On leaves where the infestation is just starting, there are purple angular leaf spots bordered by leaf veins. The more heavily infested leaves take on an almost “camouflage” appearance with darker purple, brown, yellow, and green spots. Purdue’s Plant Pest and Diagnostic Lab confirmed the diagnosis of foliar nematodes.
Another find at the same box store was several perennial hibiscus plants infested with seed beetles (family Bruchidae, species Althaeus – thanks to Tim Gibb at Purdue for the identification and information about the beetle’s life cycle). I observed the adult beetles concentrated on the stamen of many flowers, but also saw them on the petals and between the sepals and petals. When disturbed, they all scurried down to hide between the sepals and petals. The adults appear to feed on pollen and lay their eggs on hibiscus seeds. The larvae burrow into the seeds and eat them from the inside out, so they are mainly a nuisance pest unless you want to collect seeds from the plant.
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
I have not done many inspections lately because I am working on the kudzu eradication project. However, I want to report to you about a few issues I am seeing on my property. During the last two weeks we have had over six inches of rain at my house. This has caused a rapid development of leaf spot symptoms on many Yoshino cherry trees. The trees in my neighborhood are losing so many leaves that they will probably experience 75 defoliation by the end of the week. It looks like fall. This leaf spot issue seems to be new and occurring more frequently during the last five years. I am also seeing symptoms of Pseudocercospora leaf spot on Ivory Silk tree lilac. I had seen this disease last year in the Bloomington area and had samples confirmed by the Purdue Lab. Interestingly, I have an Ivory Pilar tree lilac planted very close to the Ivory Silk tree lilac and it does not have any leaf spot symptoms.
I would like to share with you some of my experiences with the annuals on my property this year. The container grown geraniums in my yard stopped blooming during the month of July. Once temperatures dropped below 90, they started blooming again. I also planted Black and Blue Salvia this year. The plants had good growth and are really a nice addition to a container planting. However, they are very brittle and have often suffered wind damage. I cannot say enough about Angelonia. This annual just keeps blooming and does not seem to require pinching or dead heading. The same was true about the Bacopa I have in the same container. Marigolds did okay on my property but suffered a great deal of slug damage during the last two weeks, leaving some with only the flowers present. Ageratum and Salvia splendens got completely destroyed by rabbits this year. Unfortunately they did not last a week. Last but not least, Dragon Begonias are a wonderful annual. I cannot believe how much growth occurs during a season and how they just continue to bloom. The only drawback is that they can become pot bound in smaller containers. Give them room. I do see some Botrytis on them, but other than that it is a great plant.
In central Indiana, the dreaded Japanese beetle seems to have declined a bit for 2020. I have seen some trees with very bad damage, usually Linden trees, but I have not seen nearly as much damage nor have I seen as many live beetles as I have seen in the past 3-4 years. Only at the end of the season when we all can compare notes will we know how the rest of the state faired, but for now in Central Indiana at least, damage is not nearly as widespread as previous years.
The green planthopper, Acanalonia conica, is found throughout Eastern North America. This particular specimen was blending in on the underside of some common milkweed plants, enjoying the shade on a hot day.
