Indiana Department of Natural Resources sent this bulletin at 05/17/2017 09:04 AM EDT
Weekly Review for May 17, 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.
First and foremost, we completed Btk treatments for Gypsy Moth in Porter and Kosciusko Counties today. The next round of treatments will be the Mating Disruption blocks in June. See www.GypsyMoth.in.gov for more information.
Next, I have been asked several times this spring what the yellow flowers in farm fields are. A lot of it is cressleaf groundsel, AKA Butterweed. I suggest this 2006 article from Purdue for more information.
Concerning nursery inspections, I am seeing a wide variety of things. Powdery mildew and Botrytis in greenhouses has been due to lack of sun and the inability to dry things out in the greenhouse in previous weeks. Earlier low temperatures and the need to keep greenhouses closed up also contributed. Aphids seem to be the pest of the moment, though I have seen a good deal of successful control. I have noticed an uptick of thrips and potato leaf hoppers in the last couple of days as well. Whichhazel gall aphid on river birch, maple bladder gall on red maples, and boxwood leaf miner symptoms on boxwoods round out my finds this week.
I am finding lots of aphids feeding on a variety of plants. The heaviest populations are on spirea, potentilla, roses and crabapple. I also saw young grasshoppers feeding on potentilla, spittle bug on potentilla, witchhazel gall aphid on river birch, frost injury on yew and boxwood and shot hole fungus on weeping cherry. At one inspection I found a rose exhibiting virus like symptoms. Samples were sent to PPDL for testing and the results confirmed the presence of Apple mosaic virus. The results also showed elevated OD levels for Prunus necrotic ringspot virus. These two viruses are part of the rose mosaic complex which is known only to be transmitted through vegetative propagation of infected stock. Infected rose plants with this complex show reduced vigor and are typically unmarketable, however the flowers don’t appear to be affected.
Photo 1, 2 – Witchhazel Gall Aphid on River birch
Photo 3 – Aphids
Photo 4 – Grasshopper on Potentilla
Photo 5 – Spiddle bug on Potentilla
Photo 6 – Rose Mosaic Complex
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
During the last week I have observed twospotted spider mite on daylilies in Greene and Vigo counties. I was surprised to find these population with all of the recent rainfall, but they were active at low levels. Still no maple mites, but I am seeing a slow increase in leafhopper activity. Woolly birch aphids have been found causing leaf distortion on river birch. I also found currant blister aphid feeding on red currant. The damage symptoms from this pest appeared as leaf puckering and looked similar to the disease that causes oak leaf blister and peach leaf curl disease. When I turned the leaf over I saw some aphids feeding on the undersides of the leaves. After some research I determine that the leaf damage was associated with feeding from currant blister aphids. This is a new pest for me. There were not a large number of aphids on the plants but blister was fairly severe. Another new pest for me this year was the Chrysanthemum lace bug I found feeding on golden rod. This species was confirmed by Cliff Sadof at Purdue. The lace bugs were very small and numerous individuals were able to fit on a single golden rod leaf. No bagworm hatch has been observed so far this year and I have not seen any spruce spider mite damage in the locations I have inspected.
Photo 7 – Currant Blister Aphid Damage
Photo 8 – Currant Blister Aphid Damage to Individual Leaf
Photo 9 -
Chrysanthemum Lace Bug on Goldenrod
I am seeing a dramatic increase in fire blight symptoms during the last week. My neighbor’s apple tree showed a few faded, slightly wilted branches and 48 hours later it had major branch dieback. Look for blackened tissue at the end of branches that have a Shephard’s crook appearance. Prune out and destroy infected tissue. Remember to disinfect shears between each cut and cut 6-12 inches below the point of infection. Be aggressive or you will lose the battle. Certain sprays may provide some protection, but the best thing to do is plant resistant varieties. Rust on Penstemon has been quite common this year. However, I have not seen any rust on Hawthorns yet. Cedar-Apple rust symptoms are developing on susceptible varieties and I have seen some severe cases. I have not seen bacterial crown gall on Euonymus this year but I am finding bacterial crown gall on deciduous hosts. During an inspection I found a crown gall infection located at an old pruning cut on weeping cherry. This disease is easily moved by pruning shears. Powdery mildew is present on many susceptible hosts. I am also seeing spot anthracnose on flowering dogwoods.
Swarms are going strong in the state. The black locus are blooming in Northern Indiana. Tulip trees are blooming in the south. Hives are strong and doing well. In one hive I looked at on Friday, the honey super was full and almost all the frames were capped. I told the beekeeper to get another honey super on there for them to fill.
There are a few hives that are not building up real fast. This may be a poor queen or could be Nosema ceranae. The beekeeper can requeen and treat for Nosema to help. They could also kill the queen and combine them with a strong hive.
We are still waiting for queens here in Indiana. The cooler weather will slow queen production down. One beekeeper reported that the new queens were not laying yet. This may be due to the cold nights or the queen has not gone out on her mating flight. He is just keeping the queens a little longer to make sure she is ok to sell to someone.
I went to two beekeeping meetings last Thursday and Saturday. I would say we had 100 beekeepers at the Saturday meeting. There were lots of new beekeepers there. At both meeting we were able to go through hives to show new beekeepers what to look for, including the Varroa mites and small hive beetles we found.
