Indiana Department of Natural Resources sent this bulletin at 05/30/2018 02:30 PM EDT
Weekly Review for May 30, 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.
Inspection Reports I am starting to see some apple scab, but it seems to be in older, established plants rather than newer nursery stock. Powdery mildew in phlox, maple mites, aphids on roses and various perennials, and a pretty heavy year for hawthorn leaf miner rounds out my nursery finds this week.
I have spent a good bit of time this week on homeowner calls.
Maple mites are starting to become more abundant. They were found damaging the inner leaves on ‘Autumn Blaze’ Maple in Allen County last week. Rose slug sawfly is also causing moderate damage to roses.
I also found a heavy scale infestation on queen palm at one greenhouse. After sending pictures to Purdue it was determined that it was Biosduval scale, Diaspis boisduvalii. It feeds on many types of plants and is found throughout the tropics. It is a major pest of orchids in Florida.
I also came across what appeared to be oat crown rust, Puccinia coronata on ‘Fine Line’ Buckthorn. Buckthorn is an alternate host for this disease which can severely damage oats causing major yield loss.
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
Bagworms have hatched in my region. Last week during a group inspection we found bagworms on white pine in Monroe County. This is not the earliest I have ever found bagworm, however, I was surprised to see them this early because we had such a cold spring. We are rapidly accumulating growing degree days. Interestingly, the bagworms were resting on the trunks of the trees and had not yet begun to actively feed on foliage. I also found pine needle scale on white pine and red pine last week. Look for small, elongate white scales on the needles of pine. Damage associated with Zimmerman pine moth feeding was found on white pine. Damage from this pest appears as excessive sap, gummosis and sawdust on the trunks of infested trees near branch junctions. Damage from bark beetles was also found on white pine. Look for plants with a fading green color or browning. Close evaluation will reveal exit holes and bleeding. Heavily infested trees should be destroyed. Aphids continue to be a problem on many plants. Last week I found aphids on apple, birch and many herbaceous perennials. Oyster shell scale was found on serviceberry last week. Heavy infestations of this pest can cause branch dieback and can often go undetected because it small and may blend in with the color of tree bark. Look for small, gray, elongate scales on the trunks of infested trees. There are other scales that can look similar to this species, but this tends to be the more common species encountered on shade trees. Maple mites are actively feeding and two spotted spider mites continue to be found on numerous hosts. This year I have found multiple locations with two spotted spider mite infestation on daylilies. Bronze birch borer was found on European white birch in Monroe County. European white birch are highly susceptible to bronze birch borer and it is advisable to use river birch or white spire birch instead.
Last week I found tar spot on maple in Monroe County. This is the earliest I have ever seen tar spot. Look for black leaf spots that feel slightly raised when you rub your finger gently over them. This disease is typically not of major concern, but heavy infestation can cause issues. Powdery mildew as found on ninebark and can result in stunting of new growth. Symptoms of fire blight were found on apple trees in Monroe County. Look for wilting growth that develops a shepard’s crook appearance and rapidly turns black. This is a bacterial disease that can be difficult to control. Infected tissue should be pruned out and destroyed. When removing infected material, cuts should be made 12 inches below dead zone. There are some products labeled for control but they may not be very effective. Wind and rain can spread the disease. There are many cultivars that are resistant to this disease. Cedar apple rust was found on serviceberry. Look for small orange spots on the leaves. I also found serious dieback on Pieris japonica. Samples have been taken to determine if Phytophthora is the cause. However other fungi such as Botryosphaeria could also cause similar types of damage. Last week I found what appeared to be needle cast on Canaan fir. The sample I sent to the lab was confirmed to have Rhizsophaera needle cast. This is the first time I have ever seen this disease on fir of any kind.
Reports of swarms are still coming in. The quick warm up in May caught some beekeepers unprepared for the fast increase in the nectar flow. I have been out looking at lots of hives over the last couple of weeks. Most hives are building up fast. I saw a lot of honey in the brood areas. Be sure to add honey supers on top and move brood frames as needed to give the queen enough room to lay brood. You have to give that queen room to lay or the hive will swarm on you. When the queen swarms, she takes several hundred bees with her…and there goes half you honey production. The goal for beekeepers in the spring is to prevent swarming so they get honey.
Some beekeeper will have honey to take off soon. I went in my hives on Memorial Day. I have several supers of capped honey that I will be taking off next weekend. Since I am in Central Indiana, southern beekeepers should have honey ready to take off, and northern beekeepers may be able to take honey off in a couple of weeks.
Beekeepers raising nucs should be ready to get them out to beekeepers. A few beekeepers have Indiana queens ready for sale now. Others breeders will have mated queens in a couple of weeks.
With this fast warm up, locus tree blooms were done early and did not last long. I already see Dutch clover blooming. Our usually nectar flow is May through June. We could use some rain here to help the plants to keep producing nectar. Then on the other hand when it is super dry and hot, the wildflowers will produce abundance of nectar to attract pollinators so they can set seed. We may have a record crop of honey this year. Beekeepers get your honey supers on and get honey. I have all mine on and need more boxes. I have a couple hives with boxes over my head!
This week I have included a photo of Anthracnose on Variegated Liriope and Thrips on Petunias. Anthracnose on Liriope is a fairly common problem. Reddish-brown spots develop along the tips and margins of the leaves and eventually you may see large areas that are browned from the tip on back down the leaf. This disease is best controlled by destruction of leaves showing symptoms and removal of any dead fallen material in the pots or beds. I thought I would share the thrip photo just because several flowers were infested with thrips, and there were also many thrips crawling along stems. It was one of the heavier thrip populations that I’ve seen in a while on any host plant.
I put almost 200 trees on stop sale from an out of state supplier because they were infested with ambrosia beetles. There were about a dozen varieties of apples, cherries and peaches. I consistently found that at each location I visited there were the same varieties infested with ambrosia beetles. They may have been shipped in infested or they may have been infested after arrival. It’s hard to say which it was but all the trees that were infested had a similar appearance with poor vigor and what looked like freeze damage. Either way they all underwent a stress event either at the production facility or here which pre disposed them to attack. There were many other trees including other fruit trees from the same supplier as well as other suppliers which showed no sign of infestation. I also spotted some unknown beetles which I sent off for an ID. In the process of trying to get all the stop sales issued I assumed they were ambrosia beetles but upon further inspection there was no gallery going into the tree but just under the bark. The hole the ambrosia beetle makes going into the tree is helpful in diagnosing the damage if you are not sure what you’re looking at.
I also found a bunch of material that had just been unloaded and still on the shipping racks which was infested with aphids and spider mites.
I found a fair amount of oyster shell scale on some red point maples. There were only small populations on scattered trees but after a while I found that some of the crawlers had hatched and were dispersing.
I was shown one of the worst aphid outbreaks I have ever seen in a landscape setting. Generally I don’t think much of aphids but when they are infesting a rose of Sharron I can make an exception. Aside from aphids there were more ladybug larvae on these plants than I have ever seen in one spot. It was a pretty impressive site.
While setting an Old World Bollworm trap I spotted what I had assumed to be a freshly erupting mulch volcano. Passing by it on my way back to the vehicle I thought it looked a little unusual. So I started digging and didn’t get past an inch of mulch before I found dirt. Then I found the burlap and basket. I assumed this must have been the last tree on Friday afternoon for the planting crew until I looked at the other trees in the row and found more of the same.
Lastly I was given a Gloomy surprise but I will hold off on announcing its identity until I get “official” confirmation.
