Indiana Department of Natural Resources sent this bulletin at 08/01/2017 02:06 PM EDT
Weekly Review for August 1, 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.
Japanese beetles are still heavy and causing quite a bit of damage on a variety of plants. New for this week is what appeared to be a rust on white oak. I have never seen rust on oak before but apparently some of the pine gall rusts in the genus Cronartium use oak as an alternate host. I also came across sumac gall aphid while assisting another inspector in Elkhart County.
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
Only 0.10 inches of rain at my house last week. Mimosa webworm is quite heavy on honey locust in some landscape environments in in Monroe County, but I have not seen any infestation during my nursery inspections. Fall webworm infestations continue to develop of multiple hosts including sweet gum, walnut, callery pear and winterberry holly. I am not seeing large infestations of fall webworm, but they are scattered throughout my entire region. I am finding some heavy infestations of tulip tree scale on Magnolia. Look for the orange scales on branches. If enough scales are present to encircle the branch, they you may start to see significant branch dieback. Crawler stage, for this pest is in August and September, which is different than many other soft scales. Crawlers can be easily killed with a contact pesticide and this life stage provides a good opportunity for control. I also found evidence of peach tree borer on weeping cherry and Yoshino cherry during nursery inspection and on my own property. We have actually had a fairly dry July in parts of my region with some heat stress. Look for gummosis and bleeding at the base of tree trunks. Frass can sometimes be seen in the gummosis. I have also found leafminer, thrips injury and twospotted spider mites on daylilies during the last week.
Powdery mildew was found on common lilac, drift roses and continues to be a major problem on Flowering dogwoods. Many flower dogwoods in my region have such heavy infestations of powdery mildew that they have stunted growth. Phyllosticta leaf spot was found on Catalpa in Monroe County. Phyllosticta is also causing serious damage to the serviceberry in my yard. Currently I have only 25% of the leaves remain on the tree. Every year I fight this problem. The tree is near my house and as my landscape matured the air circulation has decreased around the tree which has exacerbated the leaf spot issue with my tree. The tree looks like garbage. Foliar sprays during leaf expansion may help, but being close to the house it would be tricky to spray. Also, since it is a multiple stemmed tree, it would not really be a candidate for fungicide injection. My choice is to enjoy the tree in the spring time and close my eyes in mid to late summer. The tree has buds set for next year and the early defoliation does not appear to be causing serious health issues to the tree.
I was able to do two USDA Honey bee health surveys this last week. I worked on getting ready for the beekeeping event in Perry County that took place on Saturday the 29th. We had over 85 people at the event. We had great weather for the hive demonstrations we did. I demonstrated how to do splits, make nucs, and how to do a Varroa mite check. I also did presentations on diseases and pest of bees and beekeeping basics. The two hives we had for the demonstrations classes were raffled off at the end of the meeting.
Friday, we worked on the butterfly garden at the State Fair. We planted new plants in the enclosure and prepared the butterfly feeders. These feeders are different than hummingbird feeders. A butterfly feeder is flat so the butterflies can land on it and collect the sugar water inside. There is also a place on the feeder to put fresh cut fruit that the butterflies will sip on. We spruced up the outside area a little and looked at what we can do to improve the butterfly garden for next year. The butterflies will come in this Wednesday and throughout the fair.
Saving monarch butterflies and native pollinators are big things right now. For native pollinators, you want native plants. Some hybrid plants are no longer attractive to bees or butterflies. They have features that prevent bees and butterflies from landing or accessing the nectar. Simple flowers are better than multiple peddle verities. We do have to settle for some cultivated varieties since some native varieties are scare, protected or hard to propagate. While on the increase, it would be great to see even more native plants for sale in nurseries. Landscape designers – learn more about native plants and use them in your landscapes. Native plants can go great in home gardens. I have several in my home garden. My favorite is Joe-Pye weed (Eutrochium purpureum). I have several plants clumped in the back part of the garden since they do get tall. In front of them I have sneezeweed, lantana or coneflower. Then in front of these I will have smaller flowers such as tickseed, coreopsis, and some annual flowers. The big thing I have to work around is my trees I. Trees provide shade which can cause trouble for growing the sun loving plants that pollinators like. I just try new plants that will take some shade and trim up the trees so some sunlight gets to the ground. By trimming up, I mean I trim the bottom branches off. Never trim the top off. I shake my head when I see a tree company came in and topped the trees in someone’s yard. Poor trees – and how unattractive.
Purdue has several publications about Indian’s Pollinator Protection Plan. These brochures can be found at Purdue Extension Education Store. Put “Pollinator” in the search box. These publications can be purchased or downloaded for free. POL-6-W lists Indiana native plants for pollinators.
Over the past week, I’ve seen the following pests: maple mites on red maple, aphids on red oak, oak anthracnose on red oak, rust and leaf galls on bur oak, button gall on bur oak, hawthorn lace bug and hawthorn rust on thornless cockspur, fire blight on crabapple, maple petiole borer damage on red maple and pear blister mite damage to ornamental pear.
Japanese beetles seem to be winding down, still seeing a few but a lot less of them. Saw a lot of mites this week at on a variety of things including service berry, a lot of oaks, maples, and found more mites on bald cypress. We had a grower concerned about Japanese maple scale but we had a hard time finding any on the hornbeams he thought it was on. We did manage to find it on his service berry, though. Saw some defoliation damage from catalpa worms both in the nursery and widespread in the landscape. Lastly we found an assassin bug having one of the few remaining Japanese beetles for lunch.
I am working to get the last few nurseries in Elkhart and Marshall Counties done. At this point, I am seeing a lot of the same. Japanese beetle and red-headed flea beetle damage is significant in some nurseries, but there’s nothing to be done at this point. Same with spider mite injury and most of the foliar diseases like powdery mildew or anthracnose.
I have seen a few things that can be dealt with, however. Black knot can girdle branches and cause cracks opening the tree to other diseases. On large trees, galls may not do much damage. But smaller nursery trees, especially the plums, can be severely disfigured by this disease. Galls can be pruned out by removing at least 4 inches behind the knot and destroying the branches to prevent further spread of the spores. Black knot is prevalent in the environment so selecting resistant varieties is an important management strategy.
Speaking of cherries, this time of year you can find all kinds of holes in the leaves. While they might look like insect feeding, the damage was probably caused by a fungus. Once the tissue in the leaf spot became neurotic, it fell out leaving a nice circular hole. This is another one of those issues that can be alarming to homeowners, but by the time they see it, it is far too late to do anything about it. In the scope of things, this is a pretty minor disease.
The dogbane leaf beetle feeds primary on dogbane and milkweed. As a pest, it’s not of major concern, but it sure is photogenic! Finally, I found some localized bronze birch bore exit holes on Jocquemont birch. BBB prefers the white birches and, in my experience, this cultivar is particularly susceptible.
