Indiana Department of Natural Resources sent this bulletin at 08/10/2022 09:58 AM EDT
Weekly Review for August 10, 2022
This informal report by the Division of Entomology & Plant Pathology is a commentary on insects, diseases, and curiosities division staff encounter on a week-to-week basis. Comments and questions about this report are welcome and can be sent to your respective Inspector.
Over the past week I inspected some nurseries in Allen and DeKalb counties. White pine weevil damage was light on Serbian spruce. The adults had already emerged from the leaders and moved down into the litter under the trees. Red headed flea beetle damage was moderate to heavy on many of its favorite hosts including hydrangea, red and yellow twig dogwood, weigela, itea and forsythia. Japanese beetle damage was moderate on grape, blackberry, and dawn redwood and light on oak leaf hydrangea. Eriophyid mites were heavy on buttonbush, however, the compact variety “Fiber Optics,” which was also at the same nursery, was unaffected. The galls had severely distorted the foliage on several plants of the straight species. Spider mite damage was present on “Easy Peasy” rose and bald cypress and potato leaf hoppers were present on red maples. Powdery mildew was pretty heavy on “Crimson Sentry” maple and trace to light on Monarda, plane tree, flowering dogwood and “Royal Candles” speedwell.
On July 21 spotted lanternfly (SLF) was found in Huntington. A business owner sent me a text with a photo of a single fourth instar nymph crawling across his floor and we were also forwarded information from a local Facebook group that contained a post with a photo of several fourth instar nymphs on tree of heaven. After surveying the area SLF was found in about a 30-acre area west of downtown. At this point it is unknown how the infestation started, but it’s possible it showed up via rail or on vehicular traffic. It has likely been there for several years. Old egg masses were present and many trees were coated with honey dew and sooty mold from the insect’s feeding. SLF can be easily moved from one location to another on cars, trucks, and various outdoor articles so it is important to check items before you move them. If you suspect you may have seen spotted lanternfly in your area please contact us at DEPP@dnr.IN.gov or 866-NO-EXOTIC (866-663-9684). Leave your name, contact information and the county in which you live.
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
Two-spotted spider mites continue to be a problem for many growers this year. I have observed serious two-spotted spider mite feeding injury on burning bush in landscape environments. Leafhoppers are also actively feeding on redbud. Look for white stippling on the leaves, as well as for nymphs and adults on the undersides of leaves. I am finding an abundance of leafhoppers at some locations in my region. However, I have not seen severe injury and leaf cupping on red maples this year. Red headed flea beetles continue to be active. Recently I found what appeared to be red headed flea beetle feeding injury on buttonbush (Cephalanthus). Look for irregular defoliation occurring towards the center of the leaf tissue. I am also finding damage from chrysanthemum lace bug on New England asters. Look for coarse stippling and faded white appearance on the lower leaves on infested plants. You will often see adults and nymphs that are black with clear sections on their bodies. I tried to take picture, but it did not turn out very clear. This species of lace bug will also feed on golden rod.
I am finding some nutrient deficiencies in the nurseries this year, but surprisingly not as often as other years. Perhaps the lack of excessive rainfall in my region early in the season allowed for much of the nutrients to remain in the soil instead of leaching or becoming unavailable to plants that are growing in waterlogged soils. That’s been changing recently, as some parts of my region are beginning to see excessive rainfall.
Leaf spots continue to be a problem on many plants. Recently I found leaf spots on oakleaf hydrangea. Most leaf spot disease infections do not cause serious plant health issues unless you get an abundance of leaf drop which can cause plant stress. Symptoms of Cercospora leaf spot were on redbuds. Look for small, brownish, round spots on the leaves. There are numerous species of Cercospora that can cause leaf spot symptoms in late summer. I hope to have more leaf spot pictures soon. Remember, lab tests are necessary to know exactly which pathogen is the causal agent for the leaf spots you are seeing on your plants. If you have a serious leaf spot issue that you wish to control, get the problem identified in the lab so you choose the correct product for the best results.
Powdery mildew infections continue to be an issue. Development of this fungus is favored by high relative humidity levels without leaf wetness. This problem is often easy to identify because you are looking at the white fungus growing on the surface of the leaves. I have included some pictures for fun in this week report because they were such good examples I could not resist taking a picture. Downy mildew is much more difficult to detect and can have a varying range of symptoms depending on the plant. Downy mildew is also much more harmful to plants. I hope to have some more fun stuff to share with all of you next week.
