DNR - Entomology Weekly Review, July 10


Weekly Review for July 10, 2018

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.

Eric Biddinger (Nursery Inspector & Compliance Officer) - EBiddinger@dnr.IN.gov 

High humidity means more leaf spots and mildews. I have been seeing quite a bit more black spot on roses and powdery mildew on an assortment of things over the last week. 

Japanese beetle damage is quite heavy in places, but there are areas where the population is quite light as well. I hate to have to say this, but as a reminder, Japanese beetle traps only serve to lure more beetles to your property. 

A first for me was finding a silver spotted skipper larva. While it’s widely distributed and fairly common, what makes this one unusual is finding the caterpillar outside a shelter that they usually build around themselves.


Kallie Bontrager (Nursery Inspector & Compliance Officer) - KBontrager@dnr.IN.gov

‘Tis the season of Japanese Beetle... I have noticed them on river birch, roses, larch, Accolade elm, crabapples, and purple sand cherry. I also saw Flea Beetles feeding on several varieties of weigela, hydrangea and hollyhocks. Spider mites were found on butterfly bush, arborvitae, roses and dwarf Alberta spruce.


Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov

Japanese beetles are becoming a problem at some locations in my region. During the least week I have seen them feeding on Harry Lauder’s walking stick, Fine Line buckthorn, apples, purple leaf plum and linden. Not a many new problems to report this week. The pest season is in full swing. 

During the past week I found lace bug on walnut trees in Vigo County.  Look for stippling type damage and fecal spots on the undersides of leaves. Nymphs and adults can often be seen on the under sides of leaves if feeding activity is still occurring. There are numerous species of lace bug. Some species are more host specific while others tend to have a broad host range. On shade trees I frequently encounter sycamore lace bug, birch lace bug and I have once had the opportunity to see linden lace bug in Vanderburgh County.  I also have encountered Hawthorn lace bug which can infested many plants in the Roeseaceous family. This pest cause damage to hawthorn, serviceberry, Pyracnatha and sometimes Cotoneaster. Injury to shade trees is minor, but can be of concern to clients. Severe infestation levels may stress trees, but will not result in death of trees. Lace bugs on broad leaf evergreens can be a more serious issue since they cause permanent injury to leaves that are intended to be productive, healthy leaf tissue which are to remain on the plant for multiple years. Hollies and boxwoods do not get invested with lace bugs. However, Rhododendron, Azaleas and Pieris each have their own species that can infest time. I frequently see lace bugs on Azaleas in southern, Indiana but do not often see Rhododendron and Pieris lace bugs. Recently I have been finding Chrysanthemum lace bug on asters and golden rod species. Damage can be quite noticeable from this pest. One lace bug I have not seen in the state is the fringe tree lace bug. This pest has been found feeding on tree lilac in Nebraska.  There are numerous lace bug species that can be found in the landscape.   It is best to control these pest early on in the year because multiple overlapping generations can occur which makes control difficult.

During an inspection I found galls on a hickory tree. There were two types of galls. One caused the veins on the leaves to swell while the other gall was affecting the petioles of the leaves. The gall infesting the petiole could possibly be the hickory stem leaf gall aphid. According to Johnson and Lyon, there are 29 species of Phylloxera than can cause galls on hickories. Samples have been sent to Purdue University for identification. 


Fire blight is becoming a serious issue for many susceptible plants. During the past week I found fire blight infections in primarily apples. Look for the Shepard’s crook appearance and tissue the turns black and rapidly dies. Prune out and destroy infected material and make cuts 12 inches or more below the infected tissue. I also am finding numerous leaf spots and found symptoms of Phyllosticta leaf spot on paw paw. This is interesting because on paw paw, Phyllosticta seems to coalesce into large necrotic areas while on other plants it cause a small leaf spot. There is also a species of Phyllosticta that causes tip blight on Arborvitae. My William Baffin rose in my back yard has been infected with rose rosette disease which is a virus that is vector by an Eriophyid mite called Phyllocoptes fructiphilus. The plant has not yet died but is slowly declining as more and more of the new growth is being replaced with infected growth. New healthy canes are no longer being generated and flowering is being reduced. This disease can infect any horticultural variety of roses and multiflora rose can often be a reservoir for this disease. Look for new growth that is thick and excessively thorny. Heavily infected plants should be destroyed. Keep it out of your garden.


Jared Spokowsky (Nursery Inspetor & Compliance Officer)Jspokowsky@dnr.IN.gov

I've gotten to see a couple of firsts in the last couple weeks.

I went on a diagnostic walk about in Cincinnati last week and was able to view the work of the sunflower head clipping weevil. These weevils girdle the stems of cone flowers and lay eggs in them. The girdling leaves the head of the flower hanging by a thread which will eventually fall to the ground. This process short circuits the plants natural defenses by cutting off sap flow to the head and protecting the weevil larvae from the plants defense compounds.


This same patch of cone flowers was also showing symptoms of mite feeding on the flower heads as well as aster yellows disease.


I was also able to find some callery pear with hawthorn rust, I just wish it was a little more severe. The infections I found were relatively minor.


Another once in a blue moon find was the dusky birch sawfly on some river birch.


One good thing I have noticed is that the bulk of the Japanese beetle invasion has seemed to have subsided. They are still around but there numbers seem to be significantly less or maybe I have just killed enough of them that I'm not seeing as many. Either way they have done there damage.


Angela Rust (Nursery Inspector & Compliance Officer) - ARust@dnr.IN.gov

I’ve included a couple of photos this week. One is witch hazel cone gall, which is caused by an aphid. The other is a Pseudocercospora sp. of fungus causing a leaf spot on common lilac. The Pseudocercospora was confirmed by PPDL through laboratory analysis.


Kristy Stultz (Nursery Inspector & Compliance Officer) - KStultz@dnr.IN.gov

Japanese beetle feeding continues to be an issue. I’ve even had homeowners calling worrying about the massive defoliation taking place on isolated landscape trees. While doing one inspection, virus symptoms were found on bleeding hearts and columbine plants. Samples were collected and confirmed for Tobacco Rattle Virus by Purdue’s Plant and Pest Diagnostic Lab. Tobacco Rattle Virus can infect more than 400 different species and is caused primarily via root nematodes, but can also be spread mechanically with pruning tools.


Kathleen Prough (Chief Apiary Inspector) - KPrough@dnr.IN.gov

Hot weather makes it hard on the beekeeper to get into hives. Heat stroke is no fun. The bees can also be a little bit feisty with the increase temperatures. Beekeepers have reported bees clustering on the outside of the hives. The bees will do that when the temperatures are so high. Adding another honey super can give the bees more room to hang out. The beekeeper can also tip up the top cover to help circulate the hot air out the top. The bees will collect water, sit at the front of the hive entrance and move their wings. This action blows the water into the hive creating their own kind of air-conditioning.

There have been some reports of swarming the last two seeks. These may be late due to the cold weather in April and the beekeeper not putting enough honey supers on. Beekeepers still need to make sure the queen has room to lay in the brood area. One way to do that is add another honey super on. You could also move open frames down into the brood area. Another idea is take some frames of honey, extract it, and put these frames down in the brood area making them available for the queen to lay in. 

Several beekeepers are reporting taking off a good amount of honey already and have 4 to 7 honey supers still on hives. We have to do the waiting game now as the bees to cap over the honey in the cells. High humidity and high heat slows down the capping process as it is harder to get the moisture in that honey to 18%. I do recommend that beekeepers try to get their honey supers off by middle of August so they can start their varroa mite treatments. Some of these treatments take 6 weeks to complete. Completing the treatment by the end of September will help insure that the bees hatching out in late October into November (winter bees) will be mite free and healthy.

No reports this week

Megan Abraham (Division Director & State Entomologist) - MAbraham@dnr.IN.gov

Eric Bitner (Nursery Inspector & Compliance Officer) - EBitner@dnr.IN.gov

Vince Burkle (Nursery Inspector & Compliance Officer) - VBurkle@dnr.IN.gov

Ren Hall (Nursery Inspector & Compliance Officer) RHall@dnr.IN.gov

Phil Marshall (State Forest Health Specialist) - PMarshall@dnr.IN.gov

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