Indiana Department of Natural Resources sent this bulletin at 06/27/2017 08:50 AM EDT
Weekly Review for June 27, 2017
Indiana Department of Natural Resources Division of Entomology & Plant Pathology Phone: (317) 232-4120 Our Website Inspector Territories
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.
Links can be found at the bottom of the page to manage your subscription to this list. Comments and questions about this report are welcome and can be sent to Eric Biddinger or to your respective
Inspector.
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
Japanese beetles are very abundant in certain areas of my region. This is the first time I had to treat Japanese beetles on my property in 7 years. Host infested included cherry, apple, roses, linden, winter berry holly and others. Bagworms continue to cause damage in my region and the populations are increasing in number over the last two weeks. Twospotted spider mites were found at multiple locations last week. They are thriving in the low relative humidity levels and bright sun. During the past week I found twospotted spider mite on Baptisia, Spirea, burning bush, butterfly bush, columbine and snowball viburnum. Look for stippling and faded leaves that eventually turn brown. Heavy infestations will have webbing with mites crawling on the webs. Maple mites were found on red maples in Vigo County. I continue to see damage develop on Alberta spruce as a result of earlier feeding from spruce spider mites. An ovicide application may provide control of eggs and prevent fall outbreaks. Older growth is affect first because mites feed on previous season of growth early in the season and then begin to feed on new growth as it emerges. I also found one small infestation of tulip tree scale on tulip tree, but I have not found any large populations like we experience sin 2012. I have also seen leafminers on columbine and daylily. I have seen some Azalea lace bug earlier in the season and last week I found walnut lace bug feeding on walnut. However, I have not yet seen birch lace bug or sycamore lace bug. Look for coarse stippling and blackish adults feeding gregariously on the underside of leaves. Multiple generations can occur each year.
Last week was a great week to conduct inspections. So many neat things to see. Now onto the diseases. I found rust on multiple hosts last week including holly hock rust and cedar apple rust. I did not see much rust on hawthorns yet. Look for multiple orange spots that are somewhat raised off of the leaf surface. Too late to spray this year. Next year you will need to conduct preventative fungicide applications. Powdery mildew was also quite abundant during inspections last week. I found powdery mildew on common lilac, ninebark, columbine, Coreopsis and flowering dogwoods. Powdery mildew will continue to be a problem into the fall. Treat plants with a fungicide to protect new growth. It usually does not kill plants but it can reduce growth and leave plants unacceptable to customers. Phyllosticta was found on paw paw in Vigo County. This fungal pathogen is common on many host and causes small leaf spots in which the leaf tissue falls out causing a shot hole appearance. However, on paw paw it seems to cause larger lesions. Fusicladium leaf spot was also found on persimmon last week and Septoria leaf spot was found on red twig dogwood. Black spot willow canker was found on cork screw willow. Look for branches that have stems that turn black and die. Trim out infected material and disinfect shears between cuts. Reduce the tree stress by keeping willows watered and improve air circulation among plants.
I find, year after year, my pest emergence runs about a week to week and a half behind Ken’s. And that holds true again this year as my Japanese Beetle emerged about June 21. I have a flowering almond which seems to be the beetle magnet in my yard; so much so that they don’t do a lot of damage to the roses nearby. Speaking of roses, in nurseries I found my first rose virus of the year. The incendences seem to be way down from the last couple of years. Finally, I’ve seen a good bit of slug sawfly damage on roses this year, but finally caught one of the critters feeding!
A first find for me was mealybug on Yew. I found these guys down inside the plants on the bark and older foliage. They were scattered, but a high enough population that I didn’t have to hunt too much to find them. In high numbers they can cause the foliage to yellow from their sap feeding, so control should be considered.
Other finds this week include bronze birch bore on paper birch trees from a large Michigan nursery, spidermite injury on the increase, our typical leafhopper feeding on maple and redbud, hawthorn lace bug, and a few Brown Marmorated Stinkbugs hanging around a nursery.
