Indiana Department of Natural Resources sent this bulletin at 09/03/2019 08:14 AM EDT
Weekly Review for Sept. 3, 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.
Like last week there are not many new things to report. I found caterpillars of what looked like a question mark butterfly feeding on elm at one nursery. They had eaten quite a few leaves in the top of a few trees. Fall webworm is fairly abundant right now. I found them feeding on redbud, apple, Kousa dogwood and river birch. Spidermites were moderate to heavy on honeylocust, ‘Autumn Blaze’ and ‘Redpointe’ maple and were light on red and swamp white oak. Potato leaf hopper damage was moderate to heavy on red and ‘Autumn Blaze’ maples. Japanese beetle damage was light to heavy on river birch, Kwanzan cherry, bald cypress, elm and Linden. I did see a few lingering beetles, but for the most part they are done. Tar spot was moderate on ‘Autumn Blaze’, “Autumn Fantasy’ and ‘Redpointe’ maple. Anthracnose was present on London plane tree and red oak. Powdery mildew was on Magnolia and lilac, and Septoria leaf spot was found on ‘Ivory Halo’ dogwood.
Beekeepers are getting honey off hives and starting mite treatments. Sounds like northern Indiana honey production will be above average this year. Some beekeepers up north have pulled more than 100 pound off their hives. The late blooming of plants helped decrease the summer dearth period. My hive that made it through the winter and swarmed on me gave me about 40 pounds. I could take more off but would rather let them use it and not have to feed this fall.
I did see some virus symptoms toward the end of August. A couple of beekeepers reported uncapped brood. This could be due to viruses or hygienic traits – it’s hard to tell. The symptoms I have seen were deformed wings, greasy black bees, and bees dead before they could pull themselves out of cell. Beekeepers can treat for varroa mites, requeen if possible, and treat with antibiotics or the probiotic Super DFM.
It is getting late to get a new queen. If a beekeeper cannot get a new queen, they can treat and see if the bees rebound. Some may combine it with a healthy hive or nuc. I would be worried about passing viruses onto the healthy hive. Sometimes you need to let the hive die.
Beekeepers should get their entrance reducer ready to go on. I like to put it on partially so ¾ of the entrance is still open for the bees. As September progresses, I move it in a little each week. By the end of September, the entrance reducer is in place for the winter. If beekeepers have screened bottom boards, you could put them in for the winter. You will need to put the mite board in with mite treatments oxalic acid, Formic Pro, Apiguard, or Apilife Var.
Honey supers should be taken off for the season. Clean up the frames and boxes. It is also a good time to paint the boxes if they need it. Store the frames properly so wax moths do not get in and damage the comb. Use Paradichlorobenzene crystals on stacked supers to help keep the wax moths out. Do not use Naphthalene moth balls. I have seen lots of wax moth adults flying around hives, but a strong hive will control them. Equipment off of the hive does not have bees to protect it, so you have to protect that comb off the hive.
The usual late season issues for me this week. Mites on the maples, serviceberry, and some of the oaks. Second generation of fall webworm is moving along and quite populous this year. Saw a lot of two-striped planthoppers in the nurseries this week. It doesn’t cause much feeding damage, but egg laying on the branches can cause a bit of injury and dieback.
Now please excuse me as I get on a soapbox. A nursery contacted me for a second opinion on a client’s tree. It was a Norway maple planted as a B&B in the landscape 13 years ago which wilted up over the course of this season. The initial thought was Verticillium wilt. To make a long story short, what I found instead was trunk rot and a heavy infestation of flatheaded appletree borer larva. At eight inches down, I still had not found the root flair. So what went wrong? Yes, the ball may have been planted too deep. However, my bet is that the tree was planted too deep as a bare root liner in the nursery. It’s often easier to stick a plant deep in the soil or container then to properly stake or support the plant – and it’s something I see way too often in nursery stock. From there, each time the tree gets stepped up the problem gets worse as soil and mulch are thrown up on the trunk. This poor tree took over a decade to rot off at soil level from being planted too deep. The bores were most likely secondary pests on a stressed tree.
