MSU Extension Vegetables

Weather

The past week featured temperatures that were well below normal for the time of year, resulting in crops being in a kind of “suspended animation,” which will soon change with the arrival of warmer weather. Most areas of the state got 1 inch of rain over the past week, with some west central Michigan areas getting 2 inches.

This week’s forecast calls for:

• Occasional light rain developing southwest in lower Michigan, spreading northeast during the day. Fair and dry in upper Michigan. Lingering light rain possible early Thursday, May 29. Scattered showers also possible Friday to the north. Fair, dry and warmer statewide this weekend.
• High temperatures in the 60s Wednesday, May 28, warming to the 70s this weekend. Lows generally in the 40s to low 50s through this weekend.
• Medium range outlooks call for a return of warmer than normal weather next week. Precipitation totals are forecast to remain at normal to below normal levels early, increasing to normal to above normal levels by the second week of June.

Share your GLEXPO session ideas

The organizers behind the Great Lakes Fruit, Vegetable and Farm Markets Expo (GLEXPO) are asking you to share your ideas for topics and speakers you would like to see at the conference in future years. This is your chance to provide input for an educational agenda you would like to see at GLEXPO. See more details in the Michigan State University Extension article, “Submit your session or speaker ideas for 2025 Great Lakes Fruit, Vegetable and Farm Market Expo.”

Mulch madness

Plastic mulches are widely used in onion production and provide multiple benefits, including weed suppression, increased yield, temperature and moisture retention, as well as an insect repellent. With several types of plastic mulch available, you may be wondering which one is the best fit for your operation. Below is a short summary based on a study conducted by the Vegetable Entomology Lab at Michigan State University, along with observations from growers. You can read the full study on onion thrips control with plastic mulches in the Onion World magazine.

Black mulch can help increase soil temperature early in the season but may cause the soil to become too warm during and later in the season (Photo 1).

White mulch helps retain soil moisture but does not increase soil temperatures as much as black mulch does. However, both black and white plastic mulches have been associated with higher onion thrips populations compared to bare ground, red and silver mulches (Photo 2A).

Red mulch has been shown to increase soil temperature and promote faster onion growth compared to other mulches, while also reducing onion thrips populations (Photo 2B).

Silver mulch has also been effective at reducing onion thrips numbers but may delay onion growth early in the season (Photo 2C). Not all silver mulches are equally effective at reducing onion thrips, we tested a silver mulch with a textured surface for increased reflectivity which worked much better at repelling thrips compared to a silver mulch that had a smooth surface.

Silver mulch with black mulch stripe in the center is a newer option tested by growers which we are seeing this season. The silver portion is where onions are planted and is made from a different material (smooth) than the textured silver mulch discussed above. This combination of silver and black is expected to increase soil temperature and reduce thrips pressure (Photo 2D). However, to our knowledge, no formal studies or field observations have been conducted with this combination yet. We will be monitoring its performance closely this season and will keep you updated.

Crop updates

Brassicas and greens

Transplanting or seeding of cole crops of all kinds is ongoing across the state. Insect management for flea beetles, cabbage maggot and caterpillars is underway. Symptoms that appeared to be edema were reported on cabbage. Edema of vegetable crops occurs in conditions of high soil moisture and cool, overcast conditions. Plants take up more water than they can get rid of due to reduced transpiration rates. The excess water held in plant cells cause them to rupture. As the plant tissue heals over, it leaves raised, rough-textured bumps. Certain varieties can be more susceptible to edema than others.

For more information, check out this MSU Extension article and this article from Bayer.

Cucurbits

Cucumbers, summer squash and pickling cucumbers are being planted/seeded outside. Melons and watermelons are being planted outside on black plastic. Last week’s cool wet weather has caused some early crops some stress.

Powdery mildew has been reported on cucumbers growing in greenhouses. For greenhouse disease management, check out this fact sheet developed by the Hausbeck lab at MSU. Make sure that the vegetable crop you are growing is listed for any product you consider using, and confirm that the specific disease you are targeting is also listed.

Fruiting vegetables

Tomatoes, eggplant, okra and peppers are being planted outside. Viruses have been reported.

Onions and garlic

Garlic plantings are coming along nicely on many small farms. Garlic can be delineated into two main types: softneck and hardneck. Hardnecks tend to have a firmer stalk and form scapes. Softnecks generally do not form scapes and have stalks that are flexible enough to be braided for storage or market. Hardneck varieties are further split into Porcelain, Rocambole and Purple Stripe types and softneck varieties are classified into Artichoke and Silverskin types. These different types vary in their number of cloves, flavor, storability and other attributes. MSU has two comprehensive bulletins on growing garlic: E-3371 and E-2722.

Whether or not to remove garlic scapes is an important question. Both bulletins mentioned above in the garlic section recommend removing scapes to avoid yield reductions. An article from Ontario suggests that the timing of scape removal impacts both yield and bulb size. It recommends removing scapes as early as possible (usually in early June) to minimize any negative impact on yield. However, study found that the method of removal matters. Removing scapes by hand is more effective than mowing. While mowing is less labor intensive, it can remove both scapes and leaves, which has been shown to reduce bulb size and overall yield.

Carrots and celery

Carrots and celery are at various stages. They are still in an early weed management phase.

Sweet corn

Fields are being seeded continually now and transplants are being produced in the greenhouse.

Strawberries

Early plasticulture berries started to get harvested in southwest Michigan this week.

Produce Food Safety On-Farm Readiness Reviews

Schedule an On-Farm Readiness Review today for a two-hour educational visit that takes place during the harvest season and is meant to be casual and low stress. Everything discussed during an On-Farm Readiness Review is confidential and focuses on ways to reduce risks in relation to produce safety. There is no pressure to take our advice either, we are just here to support you in your produce safety efforts.

Events

• May 29, 5:30-8:30 p.m., Produce Safety Workshop for Beginning Farmers
• May 29, 7-9 a.m. Field Crops Virtual Breakfast Series: Dry Bean Management: Data-Driven Decision (RUP/CCA)
• June 3, 10 a.m.-2:30 p.m., Beginning Farmers "Train the Trainer" Workshop - Grand Rapids
• June 5, 5:30-8:30 p.m., Soil Health Workshop for Beginning Farmers
• June 5, 7-8 a.m., Field Crops Virtual Breakfast Series: Wheat Fungicide (RUP/CCA)
• June 5, 12 p.m., Monthly Drop-in Organic Farming Q & A - JUNE 2025
• June 6, 10 a.m.-3 p.m. Beginning Farmers "Train the Trainer" Workshop - Flint
• June 10, 10 a.m.-2 p.m., AgrAbility Farm Visit in Holland
• June 10, 1-5 p.m., Beginning Farmers "Train the Trainer" Virtual Workshop
• June 12, 5:30-8:30 p.m., Integrated Pest Management Workshop for Beginning Farmers
• June 12, 7-8 a.m. Field Crops Virtual Breakfast Series: Cercospora for Sugar Beets (RUP/CCA)
• June 17, 1-5 p.m. Beginning Farmers "Train the Trainer" Workshop - Chatham
• June 18, 8:30 a.m.-12 p.m., Scouting School 2025 (Day 2)
• June 19, 7-8 a.m., Field Crops Virtual Breakfast Series: Legacy Phosphorus: The Hidden Driver of Drainage Loss (CCA only)
• June 19, 5:30-8:30 p.m., Pollinator Workshop for Beginning Farmers
• June 26, 5:30-8:30 p.m., Farm Financial Management Workshop for Beginning Farmers
• July 16 - 8:30 a.m.-12 p.m., Scouting School 2025 (Day 3)
• July 30, Edible Flint Food Garden Tour
• August 5, 12-1 p.m., Seed Treatment Webinar Series
• August 12, 12-1 p.m., Seed Treatment Webinar Series
• August 18 – 19, Northern Michigan Small Farm Conference
• August 19, 12-1 p.m., Seed Treatment Webinar Series
• August 26, 12-1 p.m., Seed Treatment Webinar Series

This work is supported by the Crop Protection and Pest Management Program [grant no 2024-70006-43569] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.