Indiana Department of Natural Resources sent this bulletin at 07/30/2020 10:49 AM EDT
Weekly Review for July 30, 2020
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. Comments and questions about this report are welcome and can be sent to your respective Inspector.
By now you have probably heard about unsolicited shipments of seeds coming from China. At this point in time, there is no evidence that this is anything more than a “brushing” scam where a vendor uses fake sales to improve ratings in the marketplace.
However, these are unknown, often unlabeled seeds which were not shipped through official channels in either the U.S. or China. There is a potential for these seeds to be invasive species, contain noxious weed seeds, or be a vector for a plant disease.
If you receive these seeds, keep the packaging and do not open the seed pack. Place the packaging and contents in a zip-top bag. Please include your name, address, phone number, and email address with the package and do one of the following:
Mail the seeds to USDA APHIS PPQ, State Plant Health Director, Nick Johnson, 3059 N. Morton Street, Franklin, IN 46131
Drop the seeds off at your local Purdue County Extension Office
Contact your local Nursery Inspector to arrange pickup of the seeds.
If you have already planted the seeds, please contact your Nursery Inspector so we evaluate the situation and conduct the necessary isolation and cleanup.
I ran across a new plant to me this week – actually a whole line of them. Crimson Sunset, Ruby Sunset, Pacific Sunset, and Urban Sunset are Norway maple and Shangtung maple crosses. With Norway being evaluated for inclusion on Indiana’s Invasive Species List, (don’t panic - just the first step in a long process) these crosses pique my curiosity. Crosses can often be less prolific seeders or produce seed that is less vigorous. If you have any experience with these trees, I’d be curious hear what you think.
I should be done with nursery inspections within the next week or so. I’m kind of getting into the “same old-same old” routine. Leafhopper damage is becoming more noticeable on maples and redbuds. Spidermite damage on maples, oaks, and burning bush, among others is becoming apparent. A couple of spots of rain over the last week should help slow that down, though. Green June beetle adults were feasting on hydrangea flowers. I don’t know that they do a lot of damage on hydrangea, but keep an eye on your garden to avoid damage to ripening fruits. Tar spot on maples, some powdery mildew on lilac, oak, and magnolia, and some wooly apple aphid here and there round out the list.
I did come across an azalea cultivar called ‘Mt. St. Helens’ that seemed to be particularly susceptible to powdery mildew.
Finally, watch out for nutrient deficiency issues, especially in containers. Heavy irrigation to make up for our high temperatures and drought conditions can lead to leaching away soluble nutrients. High pH irrigation water can also raise media pH locking up iron and manganese in the soil.
It seems like it’s a really good year for leaf hoppers. Everywhere I go I find evidence of the nymphal stages under leaves and on branches and on occasion, I’ve been able to spot an adult who will stop just long enough to get his picture taken. For the first time this season, I also saw fire blight. It was a pretty bad infection in dwarf apple trees made worse this year probably in part from the extremely late hard freeze.
Ren Hall (Nursery Inspector & Compliance Officer) - RHall@dnr.IN.gov
Last week I found Impatiens Necrotic Spot Virus on coleus at another greenhouse. I also found Streptocarpella ‘Concord Blue’ with unusual spotting, including ringspots surrounding healthy tissue at the same location. I suspected it was viral as well, especially given the INSV found on coleus nearby. However, the grower informed me that this plant is particularly susceptible to injury by cold water (similar to African violets) and he suspected that was the issue. Just to be safe, I sent samples of both the coleus and the Streptocarpella to the Purdue Plant Pest and Diagnostic Lab (PPDL) for confirmation. The coleus tested positive for INSV and the Streptocarpella, as the grower suspected, was negative for all viruses tested for, and the damage was believed to be abiotic in nature. I wanted to mention this case just to illustrate that it definitely helps to know what conditions a plant does well or poorly in and to talk to the nursery to see what may be causing problems, as well as to send samples to the lab when in doubt since they are able to scientifically confirm diagnosis in a way we aren’t capable of in the field. At another greenhouse I spotted a pretty heavy infestation of aphids on Heliopsis.
Bees are doing well. Some hives are putting a lot of honey in the brood area. If the beekeeper does nothing, the queen can run out of room for laying eggs. This can result in the hive swarming or the queen stopping her laying. Both of these are bad situations. To prevent this, put a honey super on top and see if they will store the honey up there instead of in the brood area. Another option is to pull some of the honey laden brood frames, extract the honey, and put them right back in so the queen can start laying on the frames. At this time of year drawn comb is best to give them. We are still in a dearth here in Indiana, so there is not much nectar coming in. The upcoming soybean bloom will be the next flush of nectar.
