Indiana Department of Natural Resources sent this bulletin at 05/14/2019 07:46 AM EDT
Weekly Review for May 14, 2019
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. Comments and questions about this report are welcome and can be sent to your respective Inspector.
Ren Hall (Nursery Inspector & Compliance Officer) - RHall@dnr.IN.gov
Last week I continued with nursery dealer inspections. My most interesting find was on Wichita Blue Juniper. The first thing I noticed was that there were ants crawling all over the stems, twigs, and needles. In my experience, this is usually a sign that there is some other insect infestation where the ants are feeding on honeydew, which was the case here. Upon closer inspection there were aphids all over the trees as well, crawling up and down the trunk and clustered on the twigs. I also found Dwarf Scotch Pine which had been girdled by a rope or tag. Care should be taken when buying or planting trees to make sure all tags, twine, rope, etc. are removed before they cut into the trunk and girdle the tree.
I have also been attending the Buckeye Yard & Garden onLine (BYGL) Walkabouts hosted by OSU’s Joe Boggs. These are great educational sessions for anyone wanting to learn more about plants, insects, and diseases, whether you are a novice or an expert. Also a great opportunity to experience some of the beautiful places in the greater Cincinnati area, including parks, zoos, arboreta, and cemeteries. More information about the walkabouts, and great blog articles can be found on their website here: https://bygl.osu.edu/. At last week’s walkabout, we got to see adult boxwood leaf miners swarming around boxwoods.
With the colder weather we have been getting, the bees are staying home and not flying much. The bees are out bringing in pollen any warm, sunny days they get. One Indianapolis beekeeper did report her hive swarmed on Saturday. Beekeepers will need to get in hives at the end of the week when it warms up. If you have queen cells you can split the hives. If there are no queen cells, put on honey supers.
Saturday, I was in two hives at the Northcentral Beekeepers Field Day in Westfield, IN. In one hive we found some queen cells, but this hive was week with no brood left. Not sure if the queen cells will make it though. I looked at one queen cell where the larva had dropped down to the bottom of the cell. By dropping like that, the larva is not close to the food she needs. The beekeeper taking care of the hive did say it had capped brood in it two weeks ago. There may be a new queen in there so he will need to wait and see if she starts laying. In a week he can go back in and see if the virgin queen is laying. If not he can try to introduce a queen cell. He could also introduce a frame with some fresh eggs on it so they can make a new queen. You just notch the bottom of the cells that the eggs are in and come back in three days to see if they started to make queen cells there. If no queen cells and no queen, he may have to introduce a queen nucleus to the hive. The other hive was strong and had no queen cells it. This one is in good shape for the nectar flow. Once it warms up he may want to put a honey super on.
The next trees we are looking to bloom are black locust and basswood (American linden). Both these trees produce nectar that is unique in flavor and color. Black locust honey is light in color while basswood is little darker in color. Hard to describe the taste of these two. Best I can say in not as sweet as clover honey is, but a nice flavor.
We’ve had a lot of cool and wet weather this spring in southwest Indiana. So far I’ve only had one call about ash trees dropping leaves due to ash anthracnose, but we’ve had ideal weather for it. I think probably people are assuming any leaf drop is due to emerald ash borer damage given the increasing prevalence of EAB in this part of the state.
I’ve been finding a lot of symptoms resembling downy mildew on red double knockout roses, ‘baby cakes’ blackberry and also althea varieties. A few of the other problems found this past week are: sawfly damage on knockout rose, botrytis blight on geraniums and dipladenia, boxwood leafminer damage on boxwood, black spot on hybrid tea rose, mealybug on succulents, two spotted spidermite on dipladenia and what appears to be fungal tip blight on ‘Emerald Green’ arborvitae. I’ll follow up more next week with photos after lab confirmations. This week I have included photos of the botrytis petal blight on dipladenia, the boxwood leafminer damage on Wintergreen boxwood and the sawfly damage and larva on knockout rose.
I have done a fair amount of dealers and a few grower inspections many of which have been greenhouses. I have been noticing quite a few of these locations using some biological controls and in some cases relying on complete biocontrol. I have also noticed a lot of parasitized aphids and found one of the good guys on occasion. I also found a shipment of spikes heavily infested with aphids but there was also a large population of hoverfly larvae (I don’t think this was an intentional biocontrol situation just a chance for natural predation).
With all the wet weather it’s been a banner year for cedar apple rust and I have seen huge amounts of galls across my area in SE Indiana as well as Northern Ky and the Cincinnati area. I have also seen a good deal of Dothistroma needle cast on Norway spruce which is getting noticeable with the amount of needle loss. A number of conifer pests have been found including pine needle scale, fletcher scale, striped pine scale, and probably the most interesting one twig clipping red squirrels. A home owner called me wanting to know what insect or disease would be causing her Norway spruce to drop branch tips. I suspected it was a red squirrel from the beginning but asked for a few photos to confirm my suspicions. Growing up in upstate NY, I am used to seeing squirrels clip the twigs of spruce and feed on the buds but the photos that I got were quite surprising. The ground was literally covered in a carpet under the tree. There were several other trees on nearby properties but they seem to have had an affinity for this one tree.
