Indiana Department of Natural Resources sent this bulletin at 04/21/2021 08:56 AM EDT
Weekly Review for April 21, 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.
Welcome to the 2021 edition of the Weekly Review. After a long winter, it’s good to be headed back into the field. We look forward to seeing everyone again soon!
We’d be remiss if we didn’t remind you about some educational opportunities:
EAB University continues its 2021 season talking about everything from oak wilt to spotted lanternfly. Check out recorded and upcoming sessions at emeraldashborer.info/eabu.php
Subscribe to the Purdue Landscape Report. Catch up with the latest news and research from Purdue at purduelandscapereport.org.
We will have more details about the Forest Pest Outreach and Survey Program
When you are dealing with nursery stock, a lot of pest issues could be stopped at the door. I recently inspected a greenhouse where they reported a sudden uptick in aphid issues. It didn’t take long to figure out the worst problems were on plant material from Florida. I know that space and time are always at a premium, but isolating and inspecting new stock for pest issues when it comes in will reduce the time and expense of spraying the whole greenhouse later. The silver lining was that there seemed to be a healthy population of parasitoids along for the ride with the aphids.
Spring weather is always unpredictable for Hoosiers. Forecasts this week are for some unseasonably cool temperatures, so if you have young, tender plant material sitting out or a load of annuals in full bloom, get it covered the next few nights. There’s a chance for a hard freeze for most of Indiana Tuesday and Wednesday and nighttime temperatures could remain pretty low Thursday night as well.
I’ve seen a lot of news stories indicating that due to the massive amount of plant sales in 2020, that stock may be more limited this season. Stores are definitely stocking a little slower this year. Typically, shelves are pretty full this close to Mother’s Day, but while out doing regular dealer inspections, I’ve seen lots of empty places this year.
Even though some stock may be limited in availability, it’s important to remember that Indiana’s Terrestrial Plant Rule went into full effect April 18, 2020. Remind vendors and customers that plants like Euonymus fortnei are no longer allowed to be sold, gifted, exchanged, distributed, transported, or introduced into the state. Inspectors are out issuing stop sales orders on prohibited plant material.
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
Report from March 29
Bud break is occurring on Japanese tree lilacs and star magnolias are in full flower in my region. Yoshino cherries are showing bud swell but have not begun to flower. It is a bit early to find pests, but if you look hard enough you can see issues in the landscape. Boxwood leafminer larvae are beginning to cause damage as feeding activity begins to increase with the warmer temperatures. Look for bumps on the undersides of leaves and split leaves open to reveal orange larvae that are feeding between the leaf surfaces. Control may be difficult at this time of year. Orange adults will emerge in late April or May. Control should be aimed at treating adults and early instar larvae that will occur in late spring and early summer.
I have seen some early signs of potential disease issues on Penstemon that are beginning to grow. Small lesions on the previous year’s growth that overwintered in the crown of the plant may actually be rust that will later infect new growth. I still have not figured out how to keep this plant from getting rust. Applications would need to start very early, because new growth could become infected early in the spring. If you think you may have rust on Penstemon, be sure you get a laboratory diagnosis.
I am starting to evaluate the amount of winter injury I received in my landscape this year. So far, all my Hydrangea macrophylla look really good this year with all buds above ground surviving. The lowest temperature recorded in the Bloomington area was -7F, however there were 12-14 inches of snow on the ground when this occurred, and it was not excessively windy. The deep snow cover seemed to be a lifesaver for my hydrangeas. Even cultivar Nikko Blue survived above ground. I am hopeful that I will get a good flower show in 2021.This is the first time in 10 years I have seen this much winter survival. Now all I need to do is avoid spring freeze injury.
All of my Chamaecyparis obtusa cultivars survived the winter with little injury this year. One of the newest plants I have in my yard is Picea sitchensis, or ‘Papoose’. So far so good. This plant survived the drought last year and appears to be injury free after this winter. The real test for this plant will be the hot, humid and rainy weather. I have planted this dwarf conifer in the same area where I had a Serbian spruce decline from a combination of Rhizosphaera needle casts and Stigmina needle blight. It will be interesting to see if this plant becomes infected because it is low to the ground and there is likely to be a fair amount of inoculum nearby. Yes, probably not the smartest placement of plants, but it is also an interesting experiment.
My lace leaf Japanese maples are not looking happy. I would estimate there is about 50 percent mortality on cultivar ‘Crimson Queen’. These plants suffered severe freeze injury in 2020 as well as drought conditions in June and then again in fall of 2021 when it did not rain for 60 days. I have also collected a large amount of fallen dead branches underneath my river birch trees. I also blame the severely dry conditions last fall.
Report from April 12
Eastern tent caterpillars have hatched in my region, however, I have only found one small infestation in extreme western Bartholomew County. The only other pests I am encountering are those that are being shipped into Indiana nursery dealers. During the past week I encountered winged euonymus scale (Lepidosaphes yanangicola). This scale is an armored scale that is closely related to the oystershell scale (Lepidosaphes ulmi). Its primary host is burning bush (Euonymus alatus). This scale is different from the scale that occurs on evergreen forms of Euonymus. That scale is the euonymus scale (Unaspis euonymi). The winged euonymus scale has one generation a year with the crawler stage occurring in late May or early June. Look for small oystershell-shaped scale insect in between the bark ridges on stems. This scale is very small, perhaps even a bit smaller than oystershell scale. Heavy infestations can cause brank dieback.
Another scale I found this week was what I believe to be minute cypress scale (Carulaspis minima) on emerald green arborvitae. However, the juniper scale (Carulaspis juniperi) looks very similar and can also be found on arborvitae. The only way these two species can be distinguished is through microscopic examination by a specialist. Look for small white scales on the foliage that have the appearance of a fried egg. This scale can cause leaf yellowing and I frequently find it on spring shipments of plants but have never found any populations that were causing plant damage.
During inspections I also found injury caused by rhododendron lace bug (Stephanitis rhododendrii). You may be familiar with the damage caused by azalea lace bug (Stephanitis pyriodes). The rhododendron lace bug is a closely related species, causes similar damage, and feeds primarily on rhododendron. Look for coarse stippling on the top sides of leaves. Fecal spots and active life stages can be found on the undersides of leaves during the growing season. It is a little early for these insects to be active. In this case, I found only damage and dead individuals.
I have not found a lot of disease issue yet. However, I did find one case of crown rot on lavender. Plants were wilting and close inspection of the crown reveal a fuzzy growth of spores. In this case, Botrytis was the most likely cause. This is a cool, wet weather disease. Although we have not had such conditions, these plants were packed closely together and were being overwatered. Botrytis fruiting structures will look like small clusters of grapes on the end of a stalk. Sometimes you can see these in the field when conditions are right, other times you may need to send samples to the lab for identification.
I also found low levels of needle cast on Austrian pine. There are numerous needlecast fungi that can infect pines, especially hard pines in Indiana. At this time of year look for black fruiting bodies that appear as small specks on the needles. The damage you see at this time of year occurred from last year’s infection. However, infection of new growth can result from overwintering spores. It is a good idea to clean up older infected needles and maintain good air circulation in plants. Field identification of needlecast species is really not accurate. It is a good idea to send samples for laboratory diagnosis since many of them can look similar to one another. Different species of needlecast fungi can have slightly different infection periods which will affect the timing of effective fungicide applications. Be sure you know which one you have before you begin controlling it.
Swarms have started in southern and central Indiana and will soon start in northern Indiana.
I inspected a hive this week near Nashville that had several capped queen cells in it. We decided to split the hive. Now it is a waiting game for the new queens to emerge from cell (around eight days), mate (five to eight days after emerging) and start laying eggs (10 -14 days after emerging). We hope the old queen stays in the hive now that we gave her more room to lay by moving the open comb near the brood area. I also put another super on top with drawn comb to let her expand up.
Hives are bringing in lots of pollen and some nectar. An old time beekeeper adage says “If you see dandelions blooming, it’s time to put on honey supers,” so get those honey supers on! Some of the hives that made it through the winter are really strong.
I have talked to some beekeepers that have not been in their hives yet. Once we have 60 degree weather you should get in your hives. You should be seeing frames with capped and uncapped broods as well as drone broods. Look for the queen to be laying in the bottom super. If she is up higher you could switch hive boxes. You might also need to move frames with open cells near where the queen is laying. Always keep brood frames together because of cold nights.
People are receiving package bees from out of state. When you receive one, check the queen when you put her into your hive. If she’s not moving, call your source and let them know. Any problem with the packaged contact the company immediately. Beekeepers are grafting queens, so you should be able to get Indiana queen bees in about 30 days.
