Indiana Department of Natural Resources sent this bulletin at 06/30/2021 07:20 AM EDT
Weekly Review for June 30, 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.
As you may be aware, there are reports of sick and dying songbirds across several states including Indiana. This incident is the subject of an ongoing investigation. In the meantime, DNR Fish & Wildlife recommends removing birdfeeders. To report birds or find the latest information, please visit the Fish & Wildlife Songbird Deaths page.
As gypsy moth caterpillars get ready to pupate, we’re getting lots of reports of defoliation. If you see gypsy moth or need to report defoliation, email DEPP@dnr.IN.gov and include your contact information and location please.
Japanese beetle flight season has officially begun. I was fortunate enough to do inspections in south-central, central and northeastern Indiana last week and saw Japanese beetle at each of the inspections. There were just a few adults out, and damage was light so far, but it’s just the start of flight season so we should see a lot more in the coming weeks.
In central Indiana, red-headed flea beetle, Systena frontalis, has been causing noticeable feeding damage. I typically find more damage on Itea sp., Hydrangea sp. and Weigela sp. Flea beetles overwinter as eggs in the soil and the larva feed on roots of plants. This tends to cause less damage than the adult feeding. The number of generations per year is dependent on location, but it’s been reported there are at least 3 on the Atlantic Coast in container nurseries. In this photo two adults can be seen.
Periodical cicada emergence has peaked and is fairly well finished in much of the state. In southern Indiana, flagging is evident. The small branches where eggs are laid will break off and fall to the ground. Eggs will hatch, and nymphs quickly burrow underground where they will spend the next 17 years.
Ren Hall (Nursery Inspector & Compliance Officer) - RHall@dnr.IN.gov
Last week I found impatiens necrotic spot virus (INSV) at a greenhouse I inspect annually. Last year I also found INSV on coleus at the same greenhouse. This year I found symptoms on fancy coleus varieties, ‘Flapjack’ kalanchoe, and ‘Sunpatiens’ impatiens. This virus is spread by thrips and has hundreds of known host plant species. Whenever I’ve found it, concentric ringspots have been the primary symptom, and there is always a noticeable thrips problem as well. Plants can harbor the virus without showing symptoms, so controlling the insect vector is the main way to control the spread. I’m including a microscope picture taken at Purdue Plant & Pest Diagnostic Laboratory of a thrips found on a geranium sample from the same greenhouse.
I have also started seeding cicada damage on trees both in my neighborhood and in nurseries, including oviposition furrows on the bark and flagging of affected branches. I’ve been seeing a lot of scale issues at nurseries this year, especially Japanese maple scale, tulip tree scale, and the resulting sooty mold. Other interesting finds over the past week include beech erineum mite causing galls on American beech leaves in the landscape and elongate hemlock scale on hemlocks at a nursery in southern Indiana.
Ken Cote (Nursery Inspector & Compliance Officer) - KCote@dnr.IN.gov
Most of my region received anywhere from 4-7 inches of rain last Friday. So far for the month of June I have received nearly 9 inches at my house. Too wet in many areas.
Damage from spruce spider mites and active populations of two spotted spider mites were found in many locations during the past few weeks. Look for stippling and yellowing leaves or browning of older growth on evergreen plants. Spruce spider mite has undergone diapause for now, but two spotted spider mite populations will continue to cause issues for the rest of the growing season. Treat populations at early stages to avoid damage.
Japanese beetles were found in low numbers in Monroe County on June 21. It seems that the recent storms knocked down the remaining cicada populations, but I am starting to see a lot of flagging and small broken branches associated with cicada oviposition. Bagworm is a problem in certain nurseries, but numbers continue to be low compared to most years. Look for young bagworms to cause browning from early stages of feeding at this time of year. Treat them early to avoid serious plant injury. Fall webworm was also found for the first time this year in my region. Population levels are not large, but I did find fall webworm on winterberry holly. Redheaded flea beetles were found feeding on Hydrangea paniculate, but I have not found large populations like in years past. Its early yet. Keep an eye for this pest causing Swiss-cheese like damage on the tips of new foliage. Itea, red twig dogwood, and Hydrangea panicualta are some of their preferred hosts.
Japanese maple scale was found feeding on red maple in Monroe County. This pest continues to be a problem in the nursery industry and is readily moved around in the nursery industry. When I worked in Virginia, we had Japanese maple scale confirmed on boxwoods. It is difficult to control and has a wide host range. Look for oyster shell shape scales that are whiter in appearance compared to oyster shell scale. They can look somewhat similar. Interestingly, during an inspection I found a species of Chilocorus, a beneficial ladybug feeding on the scale. These are the good guys and are all black with two red spots.
Hibiscus sawfly feeding injury was found on ‘Lord Baltimore’ perennial hibiscus, but I was not able to find any actively feeding larvae. Look for defoliation and small, pale green larvae on the undersides of leaves. I also found damage from 4 lined plant bug, but I was not lucky enough to find actively feeding adults. Look for small circular to irregular shaped feeding damage that appears somewhat like etching on leaf surfaces. This pest is active for a short time in early summer and then it is gone. In some cases, it can cause serious damage, but it is generally not a serious pest.
Long tailed mealy bug was found on greenhouse grown Ficus. Mealybugs can be a real pain because they like to hide deep inside plant buds and leaf rolls where they can avoid pesticides. Sometimes a systemic may be the best option for plants that have continual problems with this pest. Mealybugs tend to be a greenhouse pest, but there is a Taxus mealybug, which I have only ever observed this once in my time as an inspector.
Maple mites are causing issue on red maples, but the recent severe storms may have suppressed populations for a bit. Look for fine stippling on red maples. Hybrid maples such as ‘Autumn Blaze’ are very prone to maple mites. White pine weevil was found feeding on the leaders of Norway spruce. Norway spruce and white pine are the preferred host of this pest. It is too late to treat for this pest. Treat adults in April before they lay eggs.
So now on to the disease that I have encountered. Cedar-Hawthorn rust was found on ‘Winter King’ hawthorn. Look for orange spots on foliage. I did not see any cedar-quince rust. Cedar-quince rust infects fruits and causes large calls on stems.
Symptoms of needle cast were found on large white pines in my region. I did not get any confirmation in the nursery industry this year, and this problem continues to be more or less a forest and landscape issue on older trees with reduced air circulation. Look for needles turning brown and small red or brown spots on those needles. This can often result in needle drop at this time of year, which is not normal. Last year we had a very wet May and a very dry June in my region. I was thinking that we would not see this issue this year because the damage we are seeing now is a result of infection that occurred last year; however, we are seeing the problem again despite the dry June in 2020. I did not observe late summer or early fall foliar symptoms, which was common in 2018 and 2019 on infected stands. It seems that the infection occurred, but the symptom development was somewhat delayed due to the dry conditions that occurred in May, August and September of 2020.
Tar spot was found on Amur maple. This appears as irregular blackspots on the leaves of maples and can also infect hollies. At this time of year, it can also be confused with maple anthracnose; however, tar spot has a slightly raised feel to it when you rub your fingers over the leaf surface. I also found some interesting fungus causing my newly planted turf to melt out after a week of heavy rain. Dewpoints were in the mid 70s and it was just too hot to try to get the seed going. I watered the area 2 times a day, got the seed to germinate, and kept it moist.
Too moist, apparently. The seed germinated and then died. Oh well. I will probably put sod there this fall. I got some neat pictures as a result of my mistake.
Not much to report that hasn’t already been expounded on. I’ve seen a few Japanese beetles in Carroll and Marshall counties. Maple mite and leafhopper injury are becoming more apparent on maples. White pine weevil damage is showing up in both nurseries and dealers on hosts ranging from white pine, Norway spruce, blue spruce, and the occasional fir.
One concern is the amount of herbicide injury I am seeing, especially on oaks. It has mostly been light, but there are a few trees out there that I’m not sure are going to recover from the hit. If you are going to use any herbicide or insecticide, read and follow label directions.
