Indiana Department of Natural Resources sent this bulletin at 05/15/2018 10:39 AM EDT
Weekly Review for May 15, 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.
I inspected more nurseries in Allen County over the past week. At one nursery there was an entire shipment of ‘Knockout’ roses that had virus like symptoms. After samples were collected and sent to the PPDL for diagnostics it turned out to be phytotoxicity due to pesticide spray. Other problems I found were light cedar apple rust on ‘Honeycrisp’ apple; red headed flea beetle on roses; Pine bark adelgid on white pine and two spotted spider mite was found on columbine. There is still some frost injury out there, but all of the plants seem to be growing out of it.
On another note I found buckeye petiole borer affecting red buckeye in my yard last week which I’ve never encountered before. Symptoms are similar to maple petiole with wilting of random leaves on the plant. Inspection of the petiole will reveal a small pin hole where the caterpillar bores in and begins mining it. For more information, check out this write-up by Joe Boggs with OSU Extension.
Last week I reported that I had sent some scale samples to PPDL that I found on southern magnolia and I believed it was false oleander scale, Pseudaulacaspis coclerelli. The identification did come back as this species. According to the report this scale is found only in greenhouses.
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
I have seen a few more locations with eastern tent caterpillar making a total of four tents found in my entire region this year. This pest is just not out there this year. Aphid populations are rapidly increasing. The air was filled with aphids on my bike ride last night. During the last week I found serious aphid infestations on many greenhouse crops including, dahlias, sweet potato vine, morning glory, lovage, parsley and gerbera daisies. Aphids were also found on Spirea, but no woolly birch aphid were observed. Balsam twig aphid was found on Alberta spruce in Putnam County. Look for fluffy, white insects cause needling twisting on terminal growth. This pest only causes minor issue. However, I would definitely monitor Alberta spruce for spruce spider mites at this time of year.
Overhead watering will help reduce mite issues, but it has been very dry in the southern part of the state which is good for mite populations. I also found spittlebug on mints. Look for small, foamy masses that resemble spit. Nymphs or adults can be sometimes be seen inside the foam. Columbine leafminer was found in Morgan County last week. Look for serpentine mines in leaves. This never seems to kill the plants but may decrease their value for sale. Timing for treatment on this pest is tricky. It seems to appear very quickly in the spring. I have not observed bagworm hatch in my region yet. However, I found girdling damage on arborvitae caused by the silk of bagworms. Bags can be difficult to remove, but over time the silk can girdle branches. Maple bladder gall was found on silver maple in Morgan County last week, but I am not seeing wide spread issues with this pest. The galls are caused by an Eriophyid mite, and treatment must occur during leaf expansion to prevent this pest.
However, this pest rarely causes major health issue for plants and treatment really is not necessary for low level populations. I have seen some thrips activity, but I did not see much leafhopper activity yet or maple mites.
The weather has been very dry and I am not seeing many disease problems during my inspections. I found some leaf spots on Spirea. I have seen some leafspot on red twig dogwoods. Powdery mildew and botrytis were not found anywhere during my inspection this past week. During a greenhouse inspection I came upon flats of basil plants that were wilting and had yellowing leaves. Upon closer inspection I found small cankers at the base of each plant that were girdling the plants. The roots looked good, but the infection at the soil line was causing serious issues. As an entomologist, if I had to guess, this would be either Rhizoctonia or Fusarium causing this issue. It is at this point, lab tests are necessary to determine the exact causal agent that is producing the symptoms. Interestingly, these symptoms were only seen on few flats of one particular variety of basil. The other cultivars seemed to be thriving. Wet weather is forecasted for the end of this week with temperature remaining quite warm. This should promote disease development in my region. No fire blight yet!
Ren
Hall (Nursery Inspector & Compliance Officer) - RHall@dnr.IN.gov
I was out in Tippecanoe and Fountain counties last week doing dealer inspections. At two different dealers I saw lots of thrips and aphids on a wide variety of host species, and two-spotted spider mites on several host species as well. Sometimes all three pests were present on the same host plant.
I also spotted what I suspected to be symptoms of a viral infection in hybrid tea roses. I sent a sample to the lab for testing, although they were only able to rule out one of the diseases that causes rose mosaic disease (Arabis mosaic virus) due to lack of availability of testing for the other two possible causes (Apple mosaic virus and Prunus necrotic ringspot virus).
I was in Cincinnati for an educational event last week and saw leaf cupping on lilacs which was probably caused by accidental herbicide injury.
Over the past week I’ve continued to see small tents develop from Eastern Tent Caterpillar here in the far southwestern counties. I’ve been seeing a fair amount of Boxwood leafminer damage to boxwoods – Baby Gem and Green Velvet varieties. I have included a photograph of the puckering/blistering symptoms that you see on the leaves when they are being mined by the fly larva. Some of the other problems that I’ve noticed are: botrytis blight on geranium and dragon wing begonia, boxwood spider mite damage on Green Velvet boxwood and Daylily Rust on Seminole Wind Daylily. There is a lot of freeze and winter injury related symptoms on evergreens down this way, and I have been told that a lot of stock arrived into IN dealer locations with injury. Emerald Green Arborvitae, Lemon Thread False Cypress, Boulevard Cypress and Dwarf Alberta Spruce are a few of the ones with significant damage that I have seen.
