Indiana Department of Natural Resources sent this bulletin at 04/27/2017 07:20 AM EDT
Weekly Review for April 27, 2017
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.
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
Last week I was conducting greenhouse inspections and nursery dealer inspection. Aphids are becoming active in my region. During inspections I observed aphids on roses, rose of sharon and Spirea. Rose slug (sawfly) was also actively feeding in my backyard. Look for small etching type damage that makes white spots on the leaves. If you turn the leaves over you will see small greenish larvae feeding on the undersides of leaves. These are sawfly larvae and not caterpillars. I also found symptoms of ambrosia beetle feeding on Yoshino cherry. This insect becomes active when leaves start to emerge and an adults will bore into trees and kill them. It will infest primarily deciduous host, but has a wide host range. Look for tooth pick like projections sticking out of the trunks of trees. These projection will easily break off in the wind or if disturbed. This is most likely the granulate ambrosia beetle (Xylosandrus crassiucsulus), but there are some other ambrosia beetles that can cause similar damage. Heavily infested trees should be destroyed and susceptible nearby hosts can be protected with permethrin, bifenthrin or other residual insecticides. Bois Duval Scale and long tailed mealybugs were found on orchids. These two pest seemed to be a persistent problem on orchid collection and very difficult to manage.
Photo 1 – Aphids, Underside of Rose Leaf
Photo 2 – Ambrosia Beetle Frass on Yoshino Cherry
Photo 3 – Bois Duval Scale on Orchid
Cedar-apple rust was found in trace amounts on edible apples last week. This is the first time I have observed this disease this year. Botrytis was observed on Ranunculus during inspections. I am frequently encountering botrytis on geraniums, primrose and begonia; especially on plants that are overhead watered. Look for necrotic tissues or flowers with a grayish mold growing on them. Close examination with a hand lens will reveal fruiting structures that has a grape-like appearance to them. I have also seen leaf spot on Iris. This may be Didymellina leaf spot and is quite common on Iris. During wet springs, this disease can become quite an issue and severely damage plants.
I’ve been out doing a lot of dealers lately and it must be the year of crown Gall. I’ve been finding it close to twenty five percent of the time when I’m doing inspections. I’m finding it on peaches, crabapples, willow, and tons of blueberry. I also found some white pine with bark beetle which had to be destroyed, aphids on apples, spittle bug and some slight fire blight symptoms.
I’ve also been out to a couple of my conifer growers. I have observed the start of white pine weevil adults feeding. Spider mites were fairly active at one of my growers with a number of trees in multiple blocks having damage (Canaan fir and Norway spruce). I also found some dieback on the Canaan firs which appears to be fungal in nature with a canker at the base of infected branches. A sample is being sent off to the lab for testing. Initially the grower had lots of damage but much of it proved to be mower damage with broken limbs. One block of Norway spruce that was inspected appeared to have a bad case of rhizosphaera needle cast (along with the blues).
Photo 7 – Canaan Fir with branch dieback
Photo 8 – Canaan Fir with possible canker at base of branch
Daytime temperatures down here in far southwest Indiana along the Ohio River have been fluctuating between upper 60’s and low 80’s, with night temperatures mostly at 55 to 60F. We had some freezes in late March, and had losses of blooms on some early flowering trees and shrubs but overall I would say damage to nursery stock and landscape plants was fairly minor from what I have seen. I saw Eastern Tent Caterpillar emergences and small webs a few days before Easter weekend. Rose slug sawfly larvae are actively feeding on roses at this time.
We are preparing for upcoming gypsy moth larval treatments in northern Indiana, and have had egg hatch at a few of the sites that we are monitoring. It appears that we will be on a normal timing this year for Btk treatments, with treatments likely occurring sometime during the first couple weeks of May.
