Indiana Department of Natural Resources sent this bulletin at 07/25/2017 08:39 AM EDT
Weekly Review for July 25, 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.
I inspected nurseries in Allen, Grant and Wells Counties this past week. Japanese beetles seem to be a lot worse this year and they are causing quite a bit of damage on Linden trees. I also saw them feeding on crabapple, Norway maple and red bud. Spider mites were causing moderate to heavy damage on red maple, ‘Autumn Blaze’ maple, honey locust, weeping willow and Canaan fir. Potato leaf hopper was present on red and ‘Autumn Blaze’ maple, and red bud. Oystershell scale had killed back a few branches on red maple at one nursery in Wells County. White pine weevil was present on white pine in Grant and Allen counties. Leaf roller caterpillars were feeding on red bud in Allen County, and aphids were feeding on tulip tree, Callery pear and silver maple. As for diseases powdery mildew was present on common lilac, needlecast was widespread on blue spruce, eyespot fungus was present on silver and ‘Autumn Blaze’ maples, tar spot was present on Norway, red, silver and ‘Autumn Blaze” maples, and Cercospora leaf spot was present on honey locust.
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
Finally received some good rain in my region this weekend. I do not have many new pests to report this week. I got lab results back on the canker I found on Acer pensylvanicum and it was confirmed as Botryosphaeria and was not the bacterial disease, Psuedomonas, which is what it appeared to be in the field. Field ID of many disease is not practical. When in doubt, send it to the lab and never be too confident that you know what something is. Remember, when you see a problem on a plant, you are often observing the plant’s response to a causal agent, which can be similar for different types of diseases. One interesting thing I did find last week were Eriophyid galls on fragrant sumac during a group inspection. It was similar in appearance to the galls I see on poison ivy every spring.
Last week I conducted the Thousand Canker Disease visual survey in Linton, IN. Most walnut trees appeared healthy but anthracnose was beginning to develop on some of the trees surveyed. Anthracnose often causes leafspot and early defoliation of black walnut on an annual basis.
One other note. This has been a bad year for Japanese beetles. I have observed large linden trees completely skeletonized. I would recommend protecting turf in order to prevent fall grub damage.
This weekend I was busy with the American Medical Veterinarian Association conference in Indianapolis. On Saturday, they had 4 sessions on honey bees that I set in on. They covered basic beekeeping, diseases and pests of bees, and antibiotic use for bee diseases. Sunday sessions were out in the bee yard going through hives. We had about 100 people at the Saturday sessions, but they only had 20 veterinarians out on Sunday. The White Lick Beekeepers Club airport bee yard was used. Good thing the beekeepers put up tents since towards the end we had heavy rain come in.
These sessions came about because on Jan. 1, 2017 a new law came into effect that the use of antibiotic on farm animals will require a prescription from a veterinarian. Beekeepers use the antibiotic Terramycin on hives to clear up European foulbrood and for prevention of American foulbrood. These diseases are caused by two different bacteria. Terramycin is also being use on what some are calling parasitic mite syndrome. A veterinarian may have to go out to the hives and see the disease before giving the beekeeper the prescription. We are all trying to understand how this will work. This will effect commercial beekeepers more than hobby beekeepers. Commercial beekeepers may have to change their standard procedures of using Terramycin every spring and fall for the prevention of American foulbrood. Most hobby beekeepers do not use Terramycin, but may have to use it for European foulbrood and parasitic mite syndrome.
Once a hive gets American foulbrood, it is burned. I do tell beekeepers to treat the other hives in that apiary with Terramycin in the fall to protect them from getting the disease. Quarantine the apiary for 18 months to make sure no other hives come down with the disease. Anything that goes into or out of that apiary stays with that apiary. This includes honey supers they may have been taken off and extracted. This is the hardest part for beekeepers with more than one apiary. They do not always keep track of what apiary the honey frames came from.
There are reports in other states of an increase in number of hives with European foulbrood. This disease can show up when the bees are under stress. We usually see it more with hives that came out of blueberry pollination. The blueberry flowers are poor in nutritional value. European foulbrood can be treated with Terramycin and requeen to get a healthy young queen in the hive. Also move the hives into a good nectar flow area.
I see more hives with what looks like parasitic mite syndrome than European foulbrood. What we see with parasitic mite syndrome is young larvae that die at about the same age as they would die from European foulbrood. When the larvae is tested it is negative for European foulbrood. It also stays white while larvae infested with European foulbrood turns yellow.
I also attended the Southeast Beekeepers meeting on the 20th. Some of the members were talking about diseases and pests. I was there to help answer any questions they were not sure about. It was a great turn out, but hot. They also demonstrated at the meeting how to do a Varroa mite check. This is important for beekeepers to do throughout the summer. If the number of Varroa mites gets over 3 mites per 100 bees sampled, the beekeeper will need to treat for Varroa mites ASAP.
Going through emails I came across the Pollinator Partnership news. They were covering events that happened for the Pollinator week of June 19 throughout the U.S. They do have some good information for how to help pollinators. Check out some of the pollinator guides they have at their site.
There is real push to help plant gardens and landscapes that benefit pollinators. As more homeowners are interested in helping pollinators, the nursery industry needs to try and provide suitable plants. Monarch butterflies are a big thing now. For nurseries that grow forbs, make sure to have native milkweed available for the larvae to eat and other forbs that the adult butterfly visits. Our native pollinators will want native plants. Plants visited by adult butterflies will have bee’s visiting them also. Native bees and honey bees on flowers will not hurt people, unless the person tries to catch the bee. Bees will ignore you and go about collecting nectar. Butterflies can be a little more skittish when you get close to them on the flower.
While doing inspections over the last couple of weeks I ran across some sweet bay magnolia with Magnolia leaf miner. I also found some white pine showing the dying leader as a result of white pine weevil. I ran across a red maple which had one limb that was dying. There is usually a good chance when you see this that it is caused by veticillium wilt. In order to try and confirm the presence of wilt I will usually break the branch and look for staining which indicates infection. I also ran across Hackberry Petiole Gall Psyllid which causes a woody gall on the petiole at the base of the leave. I don’t see this very much as opposed to Hackberry nipple gall psyllid which causes small galls on the leaves.
Japanese beetle continues its eating frenzy in the central part of the state. I have seen damage at nearly every nursery inspection I have done this year. Fortunately, we should be nearing the end of their heaviest flight period. I have noted more Phytophthora root and crown rot than I have in years past, but with the excessive rain central and northern Indiana have seen, that’s not surprising. The best way to manage for this disease is to improve watering practices. Once infected, removal and destruction of plants is best since no chemicals cure Phytophthora.
Powdery mildew also seems to be fairly heavy this season, but increasing air flow can help a great deal.
