Indiana Department of Natural Resources sent this bulletin at 04/23/2019 10:23 AM EDT
Weekly Review for April 23, 2019
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.
Invasive Pests of Trees and Gardens Workshops will be presented by Cliff Sadof of Purdue University and Carrie Tauscher of the DNR. They will teach you to recognize destructive insects and what to do if you find them. Topics will include Gypsy Moth, Spotted Lanternfly, Asian Longhorned Beetle, and more. SAF, ISA, and CCH continuing education credits are available.
The workshops will be held:
May 2, 6-7 p.m., Elkhart County Extension Office, 17746 County Road 34, Goshen, IN 46528
May 6, 5:30-7:30 p.m., The Pavilion, 1500 S Cedar St, Auburn, IN 46706
June 18, 4:30-5:30 p.m., Owen County Public Library, 10 S. Montgomery St, Spencer, IN 47460
The Terrestrial Invasive Plant Rule (312 IAC 18-3-25) when into effect on April 18, 2019. This rule designates 44 plant species as invasive. This rule goes into effect in two phases. Effective immediately, if a species is not known in Indiana, its introduction is prohibited. Second, species on this list already in trade will be prohibited for sale, distribution, trade, barter, or transport in Indiana in one year – April 18, 2020. This gives the industry time to sell down existing stock. A full list of species can be found here. If you have any questions about this rule, please contact your Nursery Inspector. We’ll be writing more about this rule as the season progresses.
Being the editor, I have the advantage of reading everyone else’s submissions then writing mine! I want to follow up on (lead into?) the downy mildew on blackberry ‘Baby Cakes’ Ken writes about. I also found it about the same time Ken did on what looks to be plants from the same nursery. I started looking around and this cultivar is the only one I have seen downy mildew on. And the plants I saw were covered to the point I thought it was an abiotic condition. It just goes to show the variability in susceptibility/resistance found in different cultivars.
Beyond that, at dealers I am mostly seeing cold injury and shipping damage.
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
It looks like we are actually going to have a spring this year. Nice weather! With that said I had a hard freeze at my house on Sunday morning. My Japanese maples made it. There was so much left over rainfall that froze that I feel it gave some added protection from the cold air. This winter killed some marginal specimens in my back yard. Plum yew, Cephalotaxus, finally died after two winters with temperatures of less than 5 below. It was fun to try to grow this plant, but our winters are just too extreme. Many of my smaller dwarf Chamaecyparis also suffered severely, especially those with small root systems. I even lost a Microbiota, but I am blaming that on the heavy rainfall in February. My Yoshino and Japanese Weeping Cherries had limited flowering due to the cold winter. I live in a frost pocket and have seen some issue with limited flowering on ornamental cherries but not all areas seem to be affected. Reduced flowering did not occur on dogwoods, redbuds, magnolias and my Japanese snowbell with an Oregon origin made it through another cold winter.
I have not observed many pests in my region yet and have primarily been inspecting plants that are being shipped into the state. Eastern tent caterpillar was active in eastern Brown County. Look for the webbing on black cherries and possibly apples. I have seen some botrytis on primrose in garden centers. This plant often get botrytis on its flowers which then infect the leaf and stem tissue and can result in destruction of the entire crown. It is a good idea to dead head this plant and give them good air circulation. I also had downy mildew confirmed on Baby Cakes blackberry. This was not something I have encountered in the past. I thought the issue could have been anthracnose or something abiotic, but downy mildew never crossed my mind. If you want a 100% identification of a disease issue, you will need to send it off for laboratory diagnosis.
I have also seen some cultural issues in garden centers. One particular case I encountered was a severe nutrient deficiency on Norway spruce which was most likely cause by plants being pot bound. Cedar-Apple rust telial horns were also observed on eastern red cedar in my region. This disease will spread from cedar trees to your susceptible apple and crabapple cultivars.
One other issue observed on a home owner property was a severe case of black knot on Canada Red chokecherry. This is a fungal disease causes olive green galls on stems that eventually turn into a black and corky structures. Severe cases can stunt growth and eventually kill trees. Pruning out infected branches can help somewhat. However, infected branches do not develop symptoms until the following year. What appears to be healthy tissue may not actually be healthy in heavily infested trees. This is a difficult problem to control and fungicide application along with pruning may be need to control the problem.
Ren Hall (Nursery Inspector & Compliance Officer) - RHall@dnr.IN.gov
Aphids, whiteflies, and thrips – oh my! Last week I was out in my territory inspecting greenhouses, and many of the usual suspects were present. I saw aphids and thrips on many plants, and the occasional whitefly. I also found powdery mildew on begonias, and two-spotted spider mites on sweet potato vine. I love this time of year, when the greenhouses have so many annual flowers in rows all in bloom at the same time – it is gorgeous!
Beekeepers are getting in packaged bees and queens already. Nucs will be ready sometime in May. Some beekeepers are already splitting hives. They are either expanding the number of hives they have to make up their winter losses or making nucs to sell.
Hives I have been in looked real strong. Drones are flying around and queens had 4-7 frames of brood. Several of the hives did have fresh nectar in the frames. I told the beekeepers to get honey supers on the hives to prevent swarming. If you give the bees plenty of room to expand, the hive may not swarm. If a hive does not swarm you will get more honey from the hive. Swarm season in Indiana is April through June.
It is warm enough now to do a varroa mite count. You could treat for varroa mites with Miteaway quick strip (formic acid) or oxalic acid. Getting the hive down to zero detected varroa mites is best for bee health.
There is a strategy called “checker boarding” that some beekeepers like to do. This is when you put in a new frame in between each frame of drawn comb through the entire hive box. It is a way to reduce crowding and get the bees to draw out more foundation. I recommend waiting until late May or June to do this. With checker boarding, you are separating brood frames. If we get a cold night the bees will try to cluster around as much of the brood as possible. The brood that is not covered with bees could get chilled and die. I like to keep the brood frames together until June and then think about checker boarding.
