Indiana Department of Natural Resources sent this bulletin at 06/05/2018 01:13 PM EDT
Weekly Review for June 5, 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.
I have been getting a bunch of Gypsy Moth calls from the area of Granger, Mishawaka, and Elkhart. It seems like the heaviest infestations are pretty localized, focused on areas of lots of white oak. The good news is the caterpillars should be about ready to pupate. The bad news is I’m getting reports of near 100% defoliation in certain areas. If you have a Gypsy Moth infestation, please let me know so we can add the location to our map.
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
During the past week I have continued to see multiple aphid infestations on various hosts. Swamp milkweed was heavily infested at many locations. Aphids have also been a problem on crabapples and edible apple trees. Fall webworm was also found in Greene County. Two spotted spider mites continue to be a problem on butterfly bush, daylilies and other susceptible hosts. Look for fine stippling type damage on host.
I am starting to see an increase in lace bug activity. During the past week I have found Chrysanthemum lace bug on golden rod and asters. I have also found azalea lace bug as well as hawthorn lace bug on serviceberry. Look for stippling type damage that will coalesce giving the leaves a whitish appearance. The stippling caused by lace bug is coarser in appearance compared to spider mites. When infested leaves are turned over, you will often see black fecal spots associated with lace bug activity. You may also see both lace bug adults and nymphs occurring on the leaves at the same time. These insects can be difficult to control due to multiple generations that occur throughout the growing season. It is a good idea to get dearly detection of these pests and treat them early to avoid getting overlapping and multiple generations. Interestingly, azaleas planted in the shade tend to have less lace bug problem because the lace bugs are more susceptible to predation in the shade and azalea plants have less stress.
I am occasionally seeing powdery mildew on a few plants, but so far it has not been a bad year for powdery mildew. During the last week I saw rust on Hollyhock and Penstemon. I also saw cedar-hawthorn rust on Winter King Hawthorn, but I did not see any cedar-quince rust. Look for the indicative, orange, rust pustules on the undersides of leaves of infected plants. Rust on Penstemon may first appear as a leaf spot with a purplish margin and a white center. However, as the infection progresses, orange fruiting bodies will appear on the undersides of leaves. Susceptible host should be treated with fungicides in order to prevent rust infections. Severe cases of rust can cause early defoliation and reduce growth on infected hosts.
During the last week I found viral symptoms on Spirea. There are several viruses that have been recently discovered on Spirea. They include Spire leaf spot virus, Spirea yellow leaf spot virus and Spirea leaf spot spherical virus. The symptoms can look similar to mild herbicide injury. These viruses are thought to be vectored by aphids. Severe infections of these viruses may cause stunted growth or some leaf deformation and yellowing of leaves. We have detected Spirea leaf spot virus and Spirea yellow leaf spot virus in the state, but not Spirea leaf spot spherical virus. These pathogens do not appear to rapidly kill infected plants. They may cause some reduce growth or cosmetic issues. Control of heavy aphid populations may reduce the risk of infection and plants with severe viral symptoms should be destroyed to reduce inoculum and threat of spread to other plants.
Swarm calls and reports are below average for May. I am not sure if it is due to high winter losses or the colder than average April. I wonder if there will be an increase swarm calls in June. We will just have to wait and see if swarms calls increase. The end of June is the end of Indiana’s swarm season. I do tell beekeepers if they get a call about a swarm in July or August that they should go and get them. It gives a good impression for beekeepers and honey bees when the beekeeper goes and pucks up the swarm. These late swarms can be put in a nuc and in September or October can be combined with another hive for the winter.
Some hives inspected in the last two weeks had a lot of honey in the brood area. You want to give that queen lots of room to lay and stay in that hive. If she does not have room, she will swarm. The beekeeper can move frames of honey out of the brood area and give them a new frame for the queen to lay eggs.
The black locust tree nectar flow was great this year. The only thing is with the high heat, the bloom was over quickly. The honey is nice and mild tasting with a light color. The tulip trees are finishing up too. Now beekeepers are waiting for the Linden (basswood) trees to bloom. Basswood honey is amber in color and has a unique taste. Clover and other perineal flowers are starting to bloom, so nectar is still coming in.
Several beekeepers are getting honey off hives now. Others are putting more honey supers on and waiting for the bees to cap the cells. I was able to take off some honey from two of my hives. I would say from color and taste that it is most likely from black locust. One hive had a deep super of honey that I took off. That is about 80 to 100 pounds of honey! I have two 5-gallon buckets of honey sitting in my kitchen waiting to be bottled. Now I’m waiting for the bees to cap the rest of the nectar on the hives.
Do not take the frame until at least 80% of the frame cells are capped. It is still considered nectar when uncapped. Once capped it is called honey. The bees cap when the nectar is around 18% moisture. We want honey at 18% or lower. Some years when the humidity is high, the bees may cap it closer to 20% moisture. Some beekeepers will mix it with real dry honey to get the moisture content closer to that 18%. Some will use a dehumidifier in the room where they store their honey to try to decrease the moisture. Others will take and uncap the frames then put them in a room with a dehumidifier to bring down that moisture. Once close to the 18%, they will extract the honey from the frames. Why so picky about moisture percentage in honey? When the moisture percentage is 20% or higher the honey could start to ferment. Fermented honey is no good to eat. I know some of you will say let’s make mead out of it since mead is made from fermenting honey. With making beer or wine you have to get that fermentation just right or else you have a poor quality product. I have tasted some good mead and tasted some poor mead.
I thought I would share some comparative photos of Boxwood Blight versus Volutella Blight on boxwoods. One photo shows symptoms on a boxwood mixed Christmas wreath that was confirmed to be infected with Boxwood Blight in December of last year. The other two photos show symptoms of confirmed Volutella Blight on boxwood at an area nursery dealer this season. Boxwood Blight caused by the fungus Calonectria pseudonaviculata is difficult to control and eradicate, and has not been confirmed at a nursery or in the landscape yet in Indiana.
However, last year a local fundraising group received in Christmas wreaths with Boxwood Blight infected stems. Although a few hundred wreaths were found and destroyed there were still a couple hundred wreaths that went to unknown locations. We are concerned about the potential introduction of this disease into Vanderburgh County. Volutella Blight caused by the fungus Pseudonectria buxi is a common disease found in Indiana on boxwoods and can be managed through pruning, disinfection of tools and destruction of infected material in most cases. The symptoms of the two diseases can look similar as shown in the photos. Boxwoods infected with Boxwood Blight typically experience a rapid defoliation of leaves in the summer. Leaves may start out with spots, turn brown and then drop. Stems also show black lesions. Boxwoods infected with Volutella Blight will also show leaf spots, have leaves turn brown but the leaves will remain attached for long periods after turning brown. Boxwoods which have leaves turning brown and dropping and that have elongated black lesions along the stems are suspect for Boxwood Blight and we would like to be notified if anyone sees these symptoms. In Vanderburgh County in particular, you can email photos directly to me.
