Indiana Department of Natural Resources sent this bulletin at 07/24/2018 08:19 AM EDT
Weekly Review for July 24, 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.
Announcements
The DNR’s Terrestrial Invasive Plants rule recently received preliminary adoption by the Indiana Natural Resources Commission. Ths rule would restrict the sale or trade of 44 invasive plant species in the state of Indiana. The rule still has several steps to go through before final adoption. This process will take a minimum of nine months. Written into the rule is a one year grace period before enforcement. The text of the rule and a timeline can be found at the bottom of the Natural Resources Commission Proposed Rule page. The public comment link is open at this time and can also be found on this page.
This past week I have noticed several leaf spots and leaf diseases including apple scab, cedar-apple rust, cedar-hawthorne rust, tar spot and Septoria leaf spot. While I haven’t seen as many Japanese beetles I have seen the damage on hollyhock, cherry, crabapple, roses, etc. Other problems included slug damage on hostas, potato leafhopper on Red Sunset maple and Autumn Blaze maple, maple mites on various varieties of maples, and spider mites on butterfly bush, burning bush and roses.
I inspected nurseries in Allen and Dekalb counties last week. Japanese beetles are still causing damage to a variety of plants although I didn’t see many adults. I found damage on Linden, crabapple, cherry, roses, chokecherry, purple leaf plum and witch hazel. Hopefully the adult flight period will be done pretty soon. Red headed flea beetle damage is pretty heavy on hydrangea, itea, weigela, red twig dogwood and ninebark. Bagworms were heavy at one nursery on Douglas fir. They had stripped many of the needles off about a dozen trees. White pine weevil had caused heavy damage to the leaders on white pine, they were in the pupa stage so expect the adults to emerge soon. I also found a light infestation of eastern spruce gall on Norway spruce. Spider mites were light to heavy on red maple, serviceberry, oak, hawthorn, ligularia, daylily, and bald cypress, and maple mites were heavy on ‘Autumn Blaze’ maple.
Pine gall rust was causing moderate branch die back on Scotch pine at one nursery. I also found heavy powdery mildew on “Crimson Sentry’ Maple with lighter infections on ‘Crimson King’ Maple. Other diseases I found were cedar-hawthorn and cedar-quince rust on hawthorn; apple scab on crabapple; needlecast on blue spruce; various leaf spots on hydrangea, black gum and redbud; black knot on ‘Canada Red’ cherry, and tar spot on ‘Crimson King’ and “Autumn Blaze’ maple.
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
I only received about 0.40 inches of rain this weekend. Locations west of Bloomington in my region received scattered rain, while locations east of Bloomington received numerous and more widespread thunderstorms over the weekend. Bagworm and Japanese beetles continue to be the most serious pests in my region. Time is running out to treat bagworms. Once they seal their bags with silk they are very difficult if not impossible to control. They need to be treated when they are actively feeding. Feeding damage is not the only damage bagworms can cause. Silk produced by bagworms that is used to attach the insect to plants can girdle branches over time. This damage may not show up until a few years after later. Spray bagworms early. Japanese beetles are beginning to taper off in my area. With the moderate amount of moisture across many parts of the state, there should be good egg laying conditions. This may result in large grub populations that will cause turf damage in late summer an early fall. Yellow necked caterpillar is the only new insect I found during the past week. Look for yellow and black caterpillars feeding in groups on deciduous trees. This pest prefers shade trees including oak, maple, walnut, elm and honey locust. (Davison, Raupp, Hellman, University of Maryland 1998). Populations can cause defoliation quite rapidly. There is a similar caterpillar called walnut caterpillar that feeds on walnut and hickory. Walnut caterpillar differs from yellownecked caterpillar by having long white hairs.
Last week I sent a sample of a leaf spot on yellowwood to the Purdue Plant and Pest Diagnostic Lab. Cercaspora species were confirmed on the submitted sample. Many times I encounter Cercaspora as small leaf spots. However, in this case, the leaf spots were quite large and covered much of the leaf. I would have never guessed this was Cercaspora when I encountered the problem in the field. Unfortunately, my pictures did not turn out that great and I do not have any for the weekly review this week.
Ren
Hall (Nursery Inspector & Compliance Officer) - RHall@dnr.IN.gov
Last week I was out in Warren County and Marion County doing nursery inspections.
I saw Red-Headed Flea Beetle feeding damage on many host plants and encountered a few of the beetles including this one on ‘Golden Vicary’ Privet.
I also found two ‘Jane’ Magnolias with Magnolia Scale. The twigs and branches were sticky with honeydew, and there was a lot of sooty mold on the leaves and branches as well.
I continue to encounter infestations of Japanese Beetle at almost every nursery I visit, sometimes with hundreds of individuals on a single host plant. Feeding damage is often severe on many of the hosts, resulting in extensive skeletonization of the leave
Lastly, I came across a row of about 20 tree lilacs, most with very unusual foliage. The leaves were twisted and discolored on most of the lower branches, and I suspect this may be the result of herbicide injury.
While Japanese beetle activity is beginning to slow, I’m still seeing a lot of damage and a few active adults. Bagworm larva are very busy completing their bags. They are getting to the development stage where insecticides are not going to be as effective so handpicking or cutting the bags from heavily infested material may be the best option right now. Bags can be pulled off material throughout the winter and until early spring when egg hatch occurs. I’ve also seen heavier infestations of lace bugs this past week.
I talked to some beekeepers that have been finding that the honey is being capped over 18.5%. If honey moisture content is higher than 18.5% the honey could start to ferment. Fermented honey is not good. You may be able to make some mead from it if you catch it early enough. Too fermented, it will not be good for mead either. Beekeepers will leave it on a little longer on the hives and hope the bees will be able to draw it down to 18% or lower. The lower humidity days we are getting will help the bees dry down the moisture in the honey in the hives. Beekeeper can also take it off and put the honey in a room with a dehumidifier. This will work, but it takes a while and you have to have a room to do it in.
Beekeepers are also starting to see small hive beetles in their hives. As long as the hive is strong and the bees are covering all the frames the bees will control the small hive beetle. I like to see the bees go after the beetles. The bees can go after the beetle’s legs. Bees will also find any small hive beetle eggs and chew them up or take them outside the hive. A strong hygienic hive in full sun is the best control for small hive beetles.
The season for honey production is coming to an end. Come August, beekeepers need to get the honey off and start treatments for varroa mites. Any honey the bees collect in mid-August till October is for their winter supply. Beekeepers that get greedy for the fall honey could end up with dead hives in late fall or next spring.
Some varroa mite treatments take 6 weeks to complete. Beekeepers want to get that treatment completed by the end of September so any bees that hatch out in October are healthy and mite free. If treatments are too late, the bees may come down with viruses (spread by the mites) and will not be strong enough to survive.
I have conducted inspections in Elkhart, St. Joseph and Caroll counties this week. Driving around, I have found several landscapes with heavy bagworm infestations, usually on arborvitae. Several of my nurseries have done a good job controlling Japanese beetle and flea beetle, but I also find these same nurseries have some of the heaviest spider mite populations. A combination of favorable dry weather and the pesticides taking out predators may have led to this boom in mites.
