Indiana Department of Natural Resources sent this bulletin at 07/18/2017 09:00 AM EDT
Weekly Review for July 18, 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.
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
Believe it or not it is actually getting dry at my house. Only 0.20 inches of rain at my location last week. Most places are beyond wet. Bagworms are still active in my region, but I am seeing fewer new infestations. Japanese beetles adults are still causing foliar injury to many host but population levels are beginning to decline. I also found cypress twig gall midge on bald cypress. Look for small, white cone-like structures towards the ends of branches. This pest usually does not cause major problems for trees but customers may not like its appearance. Bark beetles were found on white pine in Greene County. Look for white pines with a faded green color, yellowing or browning. Closer examination will reveal small, pin holes in the truck and the presence of sawdust. Heavily infested trees should be removed and destroyed. Often this is an isolated case in many plantings, but if continued problems are occurring, treatment with a residual insecticide labeled for bark beetle may be necessary. Oak apple gall was found last week in Brown County. Look for this gall to occur on the leaves. Damage from this pest is minor and not as serious as bullet oak gall and horned oak gall which occur on the twigs of oak trees. I also found oak slug last week feeding on oaks in Brown County. This pest cause a very fine skeletonization or etching on oak leaves. It is lime green to pale yellow in color. I also found leaf cutter bee round notches on the leaves of red bud. This is not a serious pest at all and is actually a beneficial insect, so you do not want to spray for the minor injury that is caused by this insect.
The continued warm, humid weather is promoting development of many plant diseases. Cedar-apple rust is so heavy on some susceptible hosts that the entire tree appears orange. It is too late to spray this year. I saw low levels of tar spot on Freeman maples last week. This pathogen causes black, slightly raised leaf spots to develop. Severe causes can causes significant leaf injury, but I have not seen many severe cases in my region. Symptoms of Cercospora leaf spot were found on black gum. Look for small, red spots on leaves that can sometimes coalesce into larger red areas. This pathogen can be unsightly but does not seem to adversely affect black gum. I also found a canker on stripped maple last week. I have never seen this before and samples are being sent to the Purdue lab for diagnosis. During a previous inspection I worked with a grower that was having an issue with leaf spot on Blueberries. This leaf spot was diagnosed as a bacterial leaf spot by Purdue University and was identified as Xanthomonas. However, it was thought to be a secondary infection as a result of an abiotic injury allowing for the infection to take place. According to Purdue, bacterial leaf spots are not a common problem on blueberries.
The weather is getting hot. Beekeepers may start to see bees bearding on the front of their hives. Bearding is where bees will hang out on the front of the hive looking like a big beard of bees. They will do that when it is hot and high humidity. They want to keep the temperature around the brood at 94-95 degrees. Some will hang outside so the hive does not get too hot with all the adults in there. I tell beekeepers to stick another honey super on top. The bees can hang out up there.
We may see less nectar coming into the hives soon. Indiana dearth period can be from mid-July to mid-August. The dearth is due to lack of foraging plants producing nectar. The high heat will make many plants stop producing nectar. Low rainfall could affect nectar production as well. I was down in Evansville last week. The crops looked good there. They did not get all the rain most of the state received. I can tell they are dry because the Dutch clover is not blooming. The Dutch clover is still blooming here in the central part of the state.
I was at the Heartland Apicultural Society meeting last week in Evansville. It had a good turnout. I was in the hives each day showing new beekeepers what to look for. I gave a talk on “What you may miss” that covered signs of when to put honey supers on as well as diseases and pests of honey bees. My big purchase was a hive scale. This allows you to weight the hive. As the hive gets heavier you know they are bringing in honey. I will be able to tell if I need to put honey supers on without having to open the hive. I will have to see about putting it on one of my hives soon.
I also did a hive inspection on Thursday. All four hives were queenless. The strongest hive did have queen cells to replace her. The other three were combined to make one hive. They were too weak to make it on their own. Small hive beetles (SHB) larvae were doing some damage to these hives also. We did put a queen cell from the strong hive into the weak hive. We also got rid of any comb that had SHB larvae on it and hoped for the best. With the weather being so hot, suppliers will not ship queens. Their best bet is to have these queens hatch and hope they take over the hives.
A beekeeper at the HAS meeting told me he was having trouble with small hive beetles taking over strong hives. Usually we have to worry about the weak hives. Something must have changed in that hive for SHB to start laying eggs. It could be that the beekeeper took honey off or the queen slowed down.
Others reported parasitic mite syndrome in hives already. This is mostly caused by viruses passed on by Varroa mites. We see bee larvae die early and it is not one of the known diseases. The beekeeper can treat for mites and treat with the antibiotic Terramycin. The antibiotic helps the bee’s strength and they are able to clean out the dead brood. The beekeeper can also requeen with a younger and hygienic queen. Offspring from the hygienic queen will clean out dead brood faster and kill Varroa mites. We have the Purdue Mite biters that go after and bite the mites. They are killing the mites and keeping the mite count below the economic threshold.
To get the antibiotic, a beekeeper needs to get a prescription from a veterinarian before they can order it from a beekeepers supply company. Some veterinarians will have nothing to do with bees. Others may want to help, but that means a visit to a bee yard, that can be $60 or more for a house call. This came into effect on January 1, 2017. It was mainly to decrease misuse of antibiotic in cattle, pigs and chickens. Since beekeepers use it also, bees were included.
I don’t have anything to report this week as far as nursery pest updates but thought I would report a bit on other activities that I have been involved in over the past week and other programs that we do: phytosanitary inspections, survey work, public relations work and environmental assessments.
All of our inspectors conduct phytosanitary inspections of plant commodities that are being shipped out domestically and internationally. Each country has specific pest concerns on different types of products and so we have the task of determining what those import requirements are, determining if we can certify those shipments and then certifying the shipment when possible. The commodities that we all inspect vary from inspector to inspector, but for me it is usually lumber, logs, corn seed, soybean seed, erosion control mats and sometimes plants.
We have a number of surveys (and pests we specifically check for) going on during different parts of the year – gypsy moth, hemlock woolly adelgid, new finds of emerald ash borer, Asian longhorned beetle, boxwood blight, sudden oak death disease, old world bollworm, thousand cankers disease… our apiary inspector checks honey bee hives). Several of us help judge 4-H fair projects during the summer, work at Indiana State Fair in August and do other public relations events. I’ve currently been working on completing our environmental assessment for the 2017 kudzu management program – a project where we are treating for kudzu at 69 sites, 74.33 acres in 28 counties. Our Division staff has a lot going on this time of year!
A follow up to the Lilac virus from a couple of weeks ago. Virus indexing was inconclusive, but the diagnosticians at Purdue and University of Minnesota felt the symptoms were characteristic of Lilac Ring Mottle Virus. Gathering samples for virus indexing can be a bit tricky. Summer temperatures can slow some viruses down to the point that they are not detectable. I have seen this a couple times with Roses. In this case, the plant is being held and if symptoms present themselves next year, it will sampled and tested again.
I spent Tuesday at the Turf Field Day at Purdue. It was a great event despite the torrential downpour in the afternoon. Many of the sessions focused on safety. It was an excellent reminder in the middle of the busy season to slow down and think about your safety procedures, equipment, and training. Accidents can take many forms and can sneak up on you from many directions.
To drive that point home, at one of my phytosanitary customers, they have a sign that marks the days since a workplace injury. It was up around 600 days in June. Last week when I showed up, it was 4 days. I never found out what the accident was, but the culture shift was palpable. Safety rules that used to be pretty lax were suddenly enforced. It’s too bad it took an accident to make this happen.
