DNR - Entomology Weekly Review, Aug. 21


Weekly Review for August 21, 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 

A nursery sent me a couple of photos from a homeowner that left me curious. In the two weeks between seeing the photos and making the site visit one of the trees went from heavy flagging on the lower branches to completely dead. I was kind of stunned when I pulled up. My best guess is that something stressed the first tree leading to an infestation of Zimmerman pine moth. Since then, the pine bark beetles have cleaned up that tree and moved on to the others in the row. Interestingly, Zimmerman only appeared to be present on the one tree. There are a high number of older red and white pines across the property making removal of these trees a high priority. 


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

I inspected nurseries in Allen County this past week. Japanese beetles are still present, but the numbers I saw were way down from previous weeks. I found them feeding on pin oak, Whitespire birch and weeping willow. Fall webworm is becoming much more abundant. I found them feeding on sweetgum and several redbud trees. Other insects and diseases I found were lace bugs on bur oak; anthracnose on London plane tree; apple scab on crabapple; European red mite on serviceberry and ‘Winter King’ hawthorn; white pine weevil on white pine and Norway spruce; flat headed apple tree Borer damage on sugar maple; maple mite on red maple; needlecast on Blue spruce and Zimmerman moth on Austrian pine.


A few of us had the opportunity to attend a training session on bur oak blight (BOB) last week in Crown Point. BOB is a disease caused by the native fungus Tubakia iowensis that mainly affects bur oak but can on occasion infect swamp white oak. It requires abundant rain in April and May to infect trees and the spores are dispersed by water droplets. It goes into a latent period after initial infection and symptoms don’t begin to appear until July. BOB is slow to develop and takes several years to spread throughout the crown with symptom progression going from the bottom up and inside out.  Early symptoms in July include black necrotic veins on the underside of the leaves. In August, these expand into wedge shaped brown lesions on the upper leaf surface along with black fruiting bodies along the veins on the underside of the leaves. The infection can spread to the petioles where it will cause the infected leaves to turn completely brown.  Infected petioles become swollen at the base and remain attached to the tree. These petioles are the source of infection in subsequent years. Bur oak trees with larger acorns seem to be resistant, however smaller acorn trees that are stressed from other problems such as two-lined chestnut borer can be killed so maintaining tree vigor is important.  Fungicide treatments using Propiconizole (Alamo) can be used on trees with moderate to severe infections, but it’s important to make the application in May to early June before the current years symptoms appear.  It’s also important to treat trees prior to infestation by two-lined chestnut borer.  Healthy trees should not be treated.


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

Well, we are certainly getting enough rain in my region.  I have not been doing many nursery inspection during the last week because I have been working on kudzu eradication during the last two weeks. Yes, kudzu exists in Indiana and has been found in the counties bordering Michigan and there was even a confirmation of kudzu in Ontario, Canada in 2009. The cold weather will not kill kudzu, but merely slow it down. During the last 13 years we have treated 125 sites in the state. I have included a picture of a kudzu site in Greene County. This is a large 5 acre site that is proving to be quite a challenge to control. Looking at a kudzu patch truly makes one appreciate and understand of the threat invasive species can cause to our environment.


Last week I was contacted by one of my growers that was a having an issue with mites on orchids.  I have inspected this location for 16 years and have never observed mites on the orchids in the greenhouse. I have heard of broad mites and cyclamen mites infesting orchids and occasionally two-spotted spider mites (Tetranychus urticae), but most of the orchid collections I have worked with never had serious mite issues because frequent overhead watering washes them off of plants.  When I arrived at the greenhouse I was amazed I what I had observed. There were so many shed skins that the undersides of the leaves appeared white.  Mites were causing pitting, sunken areas and necrosis.  It was not the stippling type damage you would expect to see with Tetranychid mites. There was not any webbing and the mites, were red and very small. They were too small to be Tetranychus cinnabarinus (Carmine Spider Mite). I believe they may be Phalaenopisis mites (Tenuipalpus pacificus) or possible Omnivorous mites (Brevipalpus californicus). Both of these mites are in the family Tenuipalpidae, the false spider mites and do not produce webbing. The hosts included Phalaenopsis and Paphiopedlum. We inspected numerous plants and believe that mites may have been introduced into the greenhouse from a shipment of plants that was received from an out of state source. I have included some interesting pictures here for your viewing pleasure. 


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

A few days ago I found this hornworm on my tomato plant, covered in pupae of a parasitic wasp. I was hoping to observe what happened over the next few days but unfortunately the hornworm disappeared during the heavy rain we had last week.


Last week I did an inspection at a small nursery with two greenhouses. They were having some problems with whiteflies. On this tomato plant, you can see the adult whiteflies. I also saw a lot of larvae on many plants, including the leaves of this strawberry plant.


I noticed some 'Zebrina' mallow that had ants busily crawling up and down the stems and sure enough they led me to an aphid infestation on the leaves.


Another interesting thing I saw was this raspberry plant that had unusual bumps all over the old stems. I was able to peel them off and they were brittle and papery and full of a sawdust-like substance. I suspected it was some type of scale insect but found no evidence of crawlers or live adult insects. I sent a sample to Dr. Cliff Sadof at Purdue who is an expert on scale insects, and he identified them as European fruit Lecanium scale.


Lastly, in the second greenhouse, this nursery was having a problem with caterpillar feeding, and I found several different caterpillar species including this white-marked tussock moth.


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

The other week I did an inspection where I might have stumbled on something new. One grower I visited was having problems with various size London Plane trees. Some of the stock was new and transplanted this spring other material was more established being put in last year. Almost all of the plants showed stem dieback with what appeared to be cankers. Below the dieback/canker the tree would be suckering badly. I took a couple of samples and sent it off to PPDL but tentatively I think it may be Canker Stain of Sycamore/Plane tree.


While doing survey for spotted lantern fly I found an interesting insect, the Ailanthus web worm. This location of Ailanthus was quiet heavily infested with the web worms but didn’t appear to be causing any great harm to the trees.


Just a few feet from my ailanthus patch I noticed a large patch of cup plant. However, I almost misted them because there was very little bloom which struck me as odd. Upon further investigation I found a very high population of sunflower head clipping weevils. Almost every flower that was still intact had multiple weevils sitting on it.


No reports this week

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

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

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

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

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

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

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

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