Indiana Department of Natural Resources sent this bulletin at 05/19/2021 07:40 AM EDT
Weekly Review for May 19, 2021
This informal report by the Division of Entomology & Plant Pathology is a commentary on insects, diseases, and curiosities division staff encounter on a week-to-week basis. Comments and questions about this report are welcome and can be sent to your respective Inspector.
Cool weather may have slowed swarms down a little. This week is forecasted to be in the 70s with warmer nights than we have had for a while. With a couple of days of rain this week, bees will swarm for sure. I hope beekeepers have their swarm traps out so they can catch some free bees. If the swarm is very large look for more than one queen.
Honey supers should be on hives. With nectar coming in since April, at least one honey super should already be on the hives. Now add two or more honey supers to be ready for the major nectar flow.
The autumn olive and bush honey suckle is blooming. I’ve seen some sweet clover already blooming in central Indiana. In the next couple of weeks, the black locust should be blooming in central Indiana. I hope to get some of that black locust nectar – it is a prized honey.
I talked to one beekeeper near Bedford who said the black locust was hit by the cold weather last week. He does not think he will get any black locust honey now. That would be two years in a row for that area. Black locust nectar flow looks good in Central and Northern Indiana. Only thing to watch out for is severe rain keeping the bees in the hive while locust is in full bloom. I am staying positive that the weather will start warming up and stay warm.
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
Aphids are becoming active and I observed aphids on Gold Flame and Vanhoutte Spirea during the last week. Aphids on Spirea usually only last a few weeks before beneficial insects begin to reduce population levels. Damage is usually not that serious on Spirea. I have not seen any leafhopper activity yet, but my guess is that they will be out later this week because temperatures are forecasted to reach the upper 80’s in my region. I have also observed winged Euonymus scale causing stunted growth on burning bush. This is easier to see when plants are dormant. However, the infestation I found this week was very large. Look for white oyster-shell shaped scale insects in between bark ridges. I had reported this find earlier in the year. I also found a cotton scale, most likely cottony camelia scale on a holly. Population levels were low in number, but large populations can cause sooty mold and dieback. Look for white cottony masses with a brown region at one end. Cottony camelia scale is more common on holly, but there is a relative of this scale insect called the cottony maple scale which is occasionally seen in Indiana.
I have not observe any cedar apple rust, apple scab, or fire blight so far this year. However, I am encountering a new problem, which is rust on roses. During the 2020 growing season I found rust on Pine Knock Out roses in Putnam and Vigo counties that were shipped to Indiana. This was the first time I had ever seen this pathogen and the Purdue Lab reports it as an uncommon problem in the state. However, this year I found the problem again in Vigo and Monroe counties on Knock Out roses shipped from out of state sources. According to Purdue University, this rust species does not require an alternate host and can spread from rose to rose. There are three species of rose rust which occur in the wild, but all of them appear similar in the field. Look for orange spots on the leaves with sporulation on the undersides of leaves. Proper fertilization can help plants grow out of the damage. Purdue recommends FRAC 3 fungicides for helping control rust on roses. IF YOU SEE RUST ON ROSE PLEASE LET THE DNR KNOW. I have never seen this problem in my career until last year and we do not want it to become a problem that is going to have an effect on many landscape roses.
Rose sawfly is not the worst thing you can have on your roses, but the insects can create a lot of highly visible damage on leaves in a very short time. I’ve started to notice damage in nurseries, but the worst place I’ve seen them is in my own back yard!
Speaking of roses, I am seeing a lot of what I suspect is early downy mildew on roses in nurseries, especially the Knock Out lines. Cultural practices that encourage dry foliage (drip irrigation, morning sun) and good air circulation (wide spacing) are critical to slowing down this disease. Fungicides may help prevent inoculation, but once the disease is established sprays are of limited use.
Last week we completed the first round of aerial gypsy moth spraying at three locations in Miami, Huntington, and Allen counties. We anticipate completing the second application later this week when weather conditions allow. You can see a first instar gypsy moth larva and a small amount of feeding damage on an oak leaf prior to last week’s treatment.
Redbud trees, and many other species, in much of the state took a hard hit with the late-season freeze and snow. These redbud trees in central Indiana are just beginning to leaf out and you can see that the flowers were all killed.
Protecting areas for native plants to thrive is a fantastic thing for parks to do when they are able, but it takes more than putting up a sign and not mowing. If left without any management at all, it’s nearly inevitable that invasive species will begin to grow and slowly displace the natives you’re trying to encourage. In this picture, you see the sign from well-meaning managers and directly next to the small red oak just beginning to leaf out is a larger, fully expanded bush honeysuckle getting ready to flower that will continue to spread without proper management.
