Indiana Department of Natural Resources sent this bulletin at 05/09/2018 01:33 PM EDT
Weekly Review for May 9, 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 nurseries in Allen County again last week. There is still a lot of freeze injury at the box stores but with the warm temperatures in the forecast I’m hoping that’s over with. I saw quite a few aphids feeding on roses and tropical hibiscus. Some roses were heavily infested and the new growth was beginning to curl. Two spotted spider mite was feeding on catnip in a greenhouse and was causing quite a bit of stippling on the foliage. Powdery mildew was heavy on ‘Fragrant Cloud’ rose at one store. It’s been too cool for this disease so I’m guessing the plants were packed in an enclosed trailer for too long which created a humid environment for it to proliferate. Other problems I encountered were mealy bugs on Adonidia palm, oleander and Rosemary; boxwood leafminer on ‘Winter Gem’ boxwood; whiteflies on tomato, mandevilla and hibiscus; Botrytis blight on geranium and New Guinea impatiens and spider mites on orange, lime, lemon and jasmine. I also found what I believe to be false oleander scale on southern magnolia. I’ve sent samples into the PPDL for confirmation. If it is false oleander scale it would be the first time I’ve encountered this pest. We also had gypsy moth caterpillars hatch on May 3 in Fort Wayne.
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
I have finally seen eastern tent caterpillar in my region. However, the infestation was in a protected valley and this is the only single infestation I have observed in my area so far this year. During the last week I continue to see an increase in aphid populations. Aphids were found on Spirea, Dahlias during inspections and I even found aphids feeding on my Japanese maple last week. Despite having a cold spring, I am finding numerous infestations of two spotted spider mites. Many of these infestation are being shipped to garden centers or are infestations that have been found in greenhouse environments. It is too early for this pest to be active in outdoor environments. Look for stippling type damage, leaf yellowing and in severe cases, webbing on the leaves. If you have two spotted spider mite infestations, I would recommend early interventions because population levels will only increase as the growing season continues. I have not seen any spruce spider mites or maple mites. I did find low levels of southern red mite on blue hollies again this week. A white scale, with round covers and yellow centers was found on Japanese weeping cherry. This scale is either the white prunicola scale (Pseudaulacaspis prunicola) or the white peach scale (Pseudaulacaspis pentagona). However, white purnicola scale is more frequently found on Japanese cherry. Large populations can completely cover the bark of infested trees. Both males and females of these species are white, but males are elongated and females are round. I did not see any leafhopper activity yet and I did not see any woolly birch aphids.
The warmer weather has relieved many of the issue associated with botrytis infections. I am starting to see more leaf spot disease during the last week. Leaf spot was found on peonies, Pieris and big leaf hydrangeas. I did not see any fire blight so far this year. It is a bit early. I did find viral symptoms on peonies and weeping yoshino cherry. The virus on Peonies could be tobacco rattle virus. The virus on the weeping yoshino cherry could be American Plum Line Pattern Virus. Serological and genetic testing would be necessary to properly identify the exact virus infecting a particular host. The best thing to do is destroy plants that have viral symptoms. If you have numerous plants that exhibit viral symptoms, then I would recommend spending the money to determine the exact virus that is causing the issue co you can evaluate your growing practices and possibly prevent future issues.
I continue to see numerous cultural issues at certain garden centers. Remember to provide plants with proper spacing. I am seeing a lot of drought injury on root bound plants that are being shipped to garden centers. These plants may need to be watered more than one time on hot dry days. I am also seeing newly received nursery stock that is remaining tied up and sitting in the hot sun. These plants may develop abiotic injury from temperature extremes if they are not untied at time of arrival. Take the time to untie these plant upon arrival so that you do not lose the salability of your investment. Yes, as an inspector this drives me crazy! Next week I hope to have some good pictures of the advancing decline on my Serbian spruce that has been confirmed with a needle cast disease.
For about the past week, I’ve noticed small tents of Eastern Tent Caterpillar in parts of Perry, Spencer, Warrick and Vanderburgh counties.
I’ve also noticed Maple bladder gall on some of the maples. This gall is caused by a small eriophyid mite. Adult mites feed on the developing leaves and the leaves respond to the irritation by rapidly producing extra cells and this forms the abnormal growth at the feeding site. The gall develops around the mite, and the mite also lays eggs within the gall. Although the galls are unsightly, they do not harm the health of the tree.
I ran across a Banded hickory borer adult. This longhorned beetle breeds in the branches and trunk of recently felled, dying or dead trees. Hickory is a preferred host, but it will breed in several kinds of hardwoods including pecan, walnut, oak and others.
