European Corn Borer has been doing damage in tasseling corn. The small ECB larva feed in the tassels as well as the developing ears. It is important to thoroughly inspect the plants as you are scouting, especially with early season corn as their damage will not always be detected in the tassel like in later planted sweet corn. The ECB moth traps were high again this week, which is consistent with the amount of damage being done in early planted sweet corn.
Japanese Beetles are also starting to increase in number. They are a pest on most any crop. They can be especially damaging to sweet corn. The beetles can defoliate the leaves, but they can also clip the silks which can prevent proper pollination from occurring.
Worm feeding on cole crops has really started to pick up. I am finding a lot of imported cabbageworms doing damage on all ages of cole crops such as cabbage and kale. The adult butterflies can be seen in large numbers in cole crop plantings laying eggs on the plants. Read more here on pests of crucifers. I saw an uptick in the population of the flea beetle as well. Keep in mind that especially on younger plants, the flea beetles can cause a lot of damage and may stunt the plant.
This hot and dry weather has been perfect weather for onion thrips. The thrips population has been high already in some areas, so this weather is favorable for large populations of thrips to develop. The thrips feeding can open the plant up to diseases such as purple blotch, so early detection and management are crucial to maintaining the health of the plant.
Downy Mildew has been confirmed, again, in southern Michigan. Considering the proximity to Ohio, it has been recommended that cucumber growers begin a downy mildew fungicide program immediately. “Managing Downy Mildew in Cucurbits”
Powdery mildew is starting to show up on cucurbit crops around the state. I have not yet had any cases in Wayne County, but this disease should be watched for closely.
Some of the field peppers I am scouting showed signs of damping off. Damping off is caused by soil borne fungi such as Rhizoctonia, Pythium, Fusarium and Phytophthora.
Angular leaf spot has started to show up on some cucurbit crops, however, the hot and dry weather has helped slow it down or stop its progression altogether. Angular leaf spot is a bacterial disease, meaning that fungicides are not effective for management of this disease.
Spotted Wing Drosophila are here. All the traps out in Wayne County were positive for SWD. These traps are out in blueberry and strawberry patches. Strawberries are winding down, but blueberries and raspberries getting ripe should be managed accordingly.
Codling Moth and Oriental Fruit Moth trap counts were down this week. Another week with our traps not over threshold.
Keep an eye out for aphids and mites in orchard crops. We are getting into the time of year where aphid and mite populations begin to increase and can do so rapidly. Leafhoppers are also a pest to be on the look out for, especially in grapes. More on Spider Mites
It is the right time to consider looking at managing summer diseases such as flyspeck, sooty blotch, and fruit rots. This can go for peaches as well with diseases such as brown rot and scab.
Necrotic leaf blotch and Alternaria leaf blotch can be found on some apple trees right now. Alternaria leaf blotch can be made worse by red mite infestations. With high populations of mites and the leaf blotch, severe defoliation can occur. More on foliar apple diseases: Leaf Spots
Another note on apples, although not a disease, the effect of freeze/cold damage can appear unsightly and may be confused for a disease. This scabby looking ring or spots on the fruit are known as “frost rings”. This is a result of the tissues being damaged in cold or freezing temperatures.
Grapes are now around the “shatter” stage where the unfertilized berries fall off the clusters. It is important to be considering proactive treatments for grape downy mildew especially if you have a variety of grapes that are susceptible to downy mildew.