Wayne County Scouting Notes from the week of June 21-June 27

Vegetable Pests

            Potato Leaf Hoppers are feeding on potato and green beans. They will also cause damage to eggplant and other crops as well. Their feeding causes what is known as “hopper burn” around the leaf edges and if left untreated, the feeding will eventually cause the leaves to turn brown and begin to die back.

Cucumber Beetles are high in numbers right now. Cucumber Beetles vector the Bacterial Wilt disease so early season control of the beetles is vital to the long-term health of the plant. Also note that as your plants are blooming, the beetles may be in the blossoms. In small enough numbers, this is okay, but they can also damage the fruit from feeding on the blossom. Consider the pollinators when planning out treatment options for cucumber beetle.

European Corn Borer is now doing damage in tasseling corn. The small ECB larva feed in the tassels as well as the 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. An ECB trap in Wayne County had 9 moths in the trap this week.

Onion thrips populations have really trended upwards. Damage from thrips occurs primarily in the center of the plant where the new growth is emerging. Heavy feeding can lead to reduced bulb size or even plant death. The thrips damage can also open the plant up to purple blotch which is able to infect the plant via the wounds created by the thrips feeding. Click here to see photos of thrips and the damage they cause.

Colorado Potato Beetle are still feeding on eggplant and potatoes. Although their numbers are not as high where there has been several treatments, their populations can quickly get out of hand.

Vegetable Diseases

            Downy Mildew has been confirmed in south west Michigan. Considering the proximity to Ohio, it has been recommended that cucumber growers begin a downy mildew fungicide program immediately. Read more from Sally Miller’s lab.

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.

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.

Fruit Pests

Spotted Wing Drosophila are starting to be found in Wayne County and surrounding areas. As more small fruits come into season, expect the number of SWD to increase rapidly. “Monitoring and Managing Spotted Wing Drosophila in Fruit Crops” 

Codling Moth and Oriental Fruit Moth traps had an increase in numbers but nothing above threshold levels.

Keep an eye out for aphids in orchard crops. We are getting into the time of year where aphid populations begin to increase and can do so rapidly. Leafhoppers are another pest to be on the look out for.

Fruit Diseases

            It is the right time to consider looking at managing summer diseases such as flyspeck, sooty blotch, and fruit rots. This note can go for peaches as well with diseases such as brown rot and scab.

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. Rich Marini from Penn State notes “Sometimes frost during bloom may not kill a flower or small fruit, but may injure the skin tissues and cause a ring of russet around the fruit and these are referred to as frost rings.” Read more here about apple skin disorders.

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.

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