Michigan vegetable crops face weather and pest challenges

Michigan vegetable growers are experiencing a mix of weather conditions and pest problems, according to Michigan State University Extension.

The Upper Peninsula has seen cooler and drier weather, while the southern parts of the state have been warmer and wetter, according to the July 31 report. This week’s forecast includes warm, humid weather with scattered thunderstorms through early Thursday, followed by more showers and thunderstorms in lower Michigan into Friday. The weekend is expected to be fair and warm, with cooler, mostly dry conditions early next week.

Corn leaf aphids have been identified in West Michigan, migrating from corn-belt states. These aphids primarily affect sweet corn, where they reproduce, but they can also land on other vegetables like tomatoes, radishes, pumpkins, celery, and carrots without reproducing. Growers are advised to monitor their crops and consider control measures for sweet corn infestations.

Hail damage was reported in Sanilac County the week of July 14, affecting various vegetable crops. The damage varies depending on the crop and stage of growth. Growers are encouraged to focus on disease control post-hail to prevent pathogen entry. Hail-damaged vine crops like melons are at risk of sun exposure and direct fruit damage, reducing marketability.

In asparagus fields, growers are focusing on protecting fern from purple spot, especially given the recent muggy weather. Brassicas and greens such as broccoli, kale, and cabbage are being harvested, with new plantings underway. Tip burn in lettuce and brassicas, caused by soil moisture-mediated calcium issues, is being managed to prevent internal rot.

Carrot and celery fields are seeing foliar diseases, managed through fungicide programs guided by TOMCAST. Scouts have reported aphids on celery field edges, and control measures have been successful.

Cucurbit crops, excluding pumpkins, are being harvested, with vigilance against downy mildew and Phytophthora pathogens. Downy mildew has been confirmed in 13 Michigan counties, affecting cucumber and melon crops. Phytophthora symptoms are expected to increase following recent rains, impacting plant crowns and fruit.

Fruiting vegetables like eggplants, peppers, tomatoes, and okra are currently being marketed. Early yellow onion harvests have started in west-central Michigan, and late blight has been detected in St. Joseph County potatoes.

Sweet corn is facing early corn leaf aphid colonization and manageable corn earworm numbers. Nightly earworm captures remain low, but growers are advised to continue monitoring.

For more detailed information, read the full report here.