Indiana Department of Natural Resources sent this bulletin at 06/07/2017 07:51 AM EDT
Weekly Review for June 7, 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.
There is plenty to find during nursery inspections this time of year. I am starting to notice an uptick in leafhoppers on maples, plenty of leaf spots and other foliar diseases, and needle casts on evergreens are easy to find. I’m still looking for spidermite issues to pop up in the field, but I have found only very limited populations.
Very few of the issues I am finding are at concerning levels. But it is where I see the issues that bother me. Lots of nurseries have “bone yards” – were you put poor quality stock out of the way until you can deal with it. And sometimes it might be there for years. This week I spotted a couple of poor quality blue spruce in such a location. The trees had a pretty heavy case of Rhizosphaera needlecase, which was being allowed to fester within the nursery as a potential source of inoculum for the newer trees being grown not far away. If you have such an area, make it a priority to see what you have there and deal with it before it becomes a larger problem.
Finally, a nursery owner asked me to look at a Juniperus rigida ‘Pendula’ in their landscape. The tree was brownish and had not grown much in the past two years. A closer look revealed a heavy infestation of Juniper scale. Given the history, I would guess that the tree came from the nursery with a small population of scale already present. This emphasizes the need to carefully look over all plant material, even plants from reputable nurseries.
Photo 1 – Juniper scale
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
Only 0.05 inches of rain in the last 10 days. Things are starting to dry up rapidly in my region as temperatures increase. Leafhoppers are active in my region and I am seeing more leaf cupping on red maple. This week I found low levels of boxwood mites on Green Mtn. boxwoods in Monroe County. I also found some active populations of spruce spider mite on Alberta spruce. No bagworm yet in my area, but very soon they should hatch. White pine weevil were found in Owen county causing injury to terminal growth of Serbian and Norway spruce. Look for wilting or dead leaders and remove them. Adults must be controlled before they lay eggs. This can be a difficult pest to control and getting good timing on the applications seems to be tricky.
Photo 2 – White Pine Weevil Injury, Serbian Spruce.
It continues to be great year for numerous plant disease issues. During the last week I observed symptoms of Phomopsis tip blight on Hetz Columnar Juniper. Look for tip dieback and cankers with a grayish area and black sporulation. Provide good air circulation for junipers and prune out infected tissue. Some fungicides are labeled for control. Avoid Juniperus scopulorum as this species is highly susceptible to tip blight. For the first time in my 15 years as an inspector I found a field of Serbian spruce with widespread needle cast symptoms. This is quite concerning, because Serbian spruce have seemed to be resistant to needle cast in the past. However, both Rhizosphaera and Stigmina needle casts were confirmed on the Serbian spruce in my yard. Perhaps Serbian spruce may no longer be a good substitute for blue spruce. Septoria leaf spot was found on red twig dogwood. I also found leaf spot developing on Peonies. Powdery mildew is a continued problem on many susceptible plants and I am starting to see Cedar-Hawthorn rust develop on hawthorns. We will likely see some new issues next week as the heat increases and the rainfall subsides.
