West central Michigan vegetable regional report – July 6, 2016
Start watching cucumbers and melons for cucurbit downy mildew. It has not been detected in Michigan, but has been found in Ontario this week.
Asparagus growers are now focusing on applying protectant fungicides for asparagus purple spot and rust. Tarnished plant bugs and Japanese beetles were active in west Michigan asparagus fields last week. Carbaryl and permethrin are helpful for Japanese beetles, while permethrin is helpful for tarnished plant bugs.
For carrots, an Oceana County aster leafhopper sample from June 27 had zero percent infectivity.
Thrips continue to be present in onions I visited this week. Consider reserving Radiant until the second half of July/early August. The forecast suggests hot weather will continue, making it important to have this good knockdown material available for late summer.
Aphids and tarnished plant bugs seem to be more abundant in carrots this year. Beleaf and Fulfill are effective aphid products.
For potatoes and tomatoes, the weather forecast is producing a high risk for late blight development for three of the next five days, with highest risk today through Friday, July 6-8. Late blight was detected on volunteer potatoes in Branch County, Michigan this week. Colorado potato beetle activity is reportedly higher this year than in recent years. We are seeing the end of the overwintering generation of Colorado potato beetles, and the start of emergence of summer adults.
For sweet corn, Insect Forecast suggests a forecast conducive to scattered flights of corn earworm into our area over the next four days. Now is a good time to get corn earworm and western bean cutworm traps established.