Michigan vegetable crop report – May 21, 2025

Benjamin Phillips<benp@msu.edu>, Benjamin Werling<werlingb@msu.edu>, Chris Galbraith<galbra53@msu.edu>, Salta Mambetova<mambetov@msu.edu>, Lyndon Kelley<kelleyl@msu.edu>, Mary Hausbeck<hausbec1@msu.edu>, Zsofia Szendrei<szendrei@msu.edu>, Zachary Hayden<haydenza@msu.edu>, Daniel Brainard<brainar9@msu.edu>, Jeffrey Andresen<andresen@msu.edu>, Vicki Morrone<sorrone@msu.edu>, Keith Mason<masonk@msu.edu>, Jaime Willbur<willbur1@msu.edu> and Jan Byrne<byrnejm@msu.edu>, Michigan State University Extension - May 21, 2025

Between wind and rain over the last week, many growers are experiencing their first field progress slowdowns.

A well-managed garlic field with effective weed suppression using straw on the ground. — A well-managed garlic planting with effective weed suppression using straw. Photo by Chris Galbraith, MSU Extension.

Weather

The week ending on Monday, May 19, featured temperatures that were 4-8 degrees above normal. Degree day accumulations (base 50 degrees Fahrenheit) are now near normal to up to 10 days ahead across Michigan. Most areas in the Lower Peninsula had been drier than normal ahead of the recent 0.5-3 inches of rainfall that accumulated. The Saginaw Valley region is a drier exception.

In summary, this week’s forecast calls for:

Mostly cloudy and cool through Friday, May 23. Occasional rain across lower Michigan Wednesday and Wednesday evening. Cool, dry and breezy to the north. Scattered showers possible Thursday and Friday to the north and east. Fair, dry and gradually warmer this weekend.
High temperatures in the 50s Tuesday through Friday, warming to the 60s this weekend. Lows temperatures generally in the upper 30s and 40s through this weekend. Scattered frost is possible in interior northern areas of the state through this weekend.
Most of the state will see 0.25-0.75 inches additional rain today, May 21, through next Wednesday.
Medium range outlooks call for cooler than normal weather to persist for the remainder of May warming back to above normal levels again in early June. Precipitation totals are forecast to remain at normal to below normal levels.
New long lead outlooks suggest warmer than normal temperatures for much of the 2025 growing season.

Sand blowing through a hole in the windbreak of an agricultural field. — Sand blowing through a hole in the windbreak. Many areas saw strong winds last week. Photo by Ben Phillips, MSU Extension.

Share your Great Lakes Expo 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.”

Weeding

A finger weeder fracturing sandy soil near the edge of a plastic row cover. — Finger weeder fracturing sandy soil near the plastic edge, and a single spyder arranged at a 45-degree angle creating a splash of soil tossed into it from the finger weeder and redirected back toward the bed shoulder. Photo by Ben Phillips, MSU Extension.

With more plastic laid, and our first run of consistent precipitation, a weed flush is coming. Where herbicides are not used, there are many options for arranging weeding tools around plastic beds. Tools that rotate in proportion with the movement of the tractor are less likely to catch and drag plastic, but they may still puncture it. Finger weeders, disc hillers, spyders and Lilliston spider gangs are some options. High clearance and good tool visibility helps limit damage. It can help to mount some behind the rear wheels too for covering tracks.

Crop updates

Asparagus

Ever eat a 1-pound burger in 15 minutes? Probably not! But that’s what the start of harvest felt like last Tuesday as west central Michigan growers picked like mad with the warm overnight temperatures.

This week is different with a more manageable pace. One thing to watch for: Extended rainfall and cooler temperatures can favor purple spot development during. Spore-producing structures overwinter on fern that was infected the previous season. Rainy weather promotes spore release. Spores infect the spears to produce the characteristic purple lesion. Sand strikes from windblown sand may be colonized by purple spot, with more lesions on that side of the spear, but injury is not needed for infection. A timely fungicide program during the fern season can reduce the amount of inoculum that overwinters to produce spores during harvest.

A purple spot lesion on an asparagus plant. — Purple spot lesions on a spear earlier this week. Symptoms may increase with the latest bout of extended rainfall and cool temperatures. The spears will still taste great! Photo by Ben Werling, MSU Extension.

Cutworms can cause very spotty issues that may appear more during cooler weather, since there is a longer time between spear emergence and harvest. White cutworm is down in the soil during the day but climbs spears to feed on tips at night. This can create crooking. If you see this damage, dig down to “confirm the worm.” Permethrin is labeled and has a one-day preharvest interval.

A white cutworm larva next to an asparagus spear. — A likely white cutworm larva found after digging around the base of damaged spears and their neighbors. The caterpillar had eaten the bracts off part of the tip, and the spear crooked. Photo by Ben Werling, MSU Extension.

Brassicas and greens

Transplanting or seeding of cole crops of all kinds is ongoing across the state. Lettuce is being planted out in the field. High tunnel spinach and winter green harvests are finishing up and replaced by warm season crops. Sidedressing and cultivation is ongoing in cabbage. Maggots are pounding untreated transplants, with cauliflower getting the worst of it on some farms.

Brassica transplants under black plastic row covers. — Transplants placed in black plastic when the highs were in the high 70s and low 80s experienced some dieback, but are recovering. Photo by Ben Phillips, MSU Extension.

Cabbage maggots in the soil near the root of cauliflower. — Cabbage maggots and root damage in cauliflower. Using row covers immediately after transplanting can help prevent pest infestation, including those by cabbage maggots. However, it’s important to note that some maggot species emerge from the soil. In such cases, covering an already infested area could trap the pests inside, worsening the problem. There are various types of row covers available. The article “Floating Row Cover” from the University of Wisconsin-Madison discusses several options. Row covers can be purchased at garden centers, retail stores or through specialized horticultural supply catalogs/websites. Photo by Salta Mambetova, MSU Extension.

Cucurbits

Cucumbers, summer squash and pickling cucumbers are being planted/seeded outside. Melons and watermelons are being planted outside on black plastic.

Powdery mildew tends to show up in cucurbit plantings towards the middle to the end of the season. Choosing and planting varieties with genetic resistance to this plant disease now is one of the few non-chemical/cultural practices for reducing risk of powdery mildew later. For a list of cucumber, squash and pumpkin varieties with known tolerance or resistance, refer to this resource from Cornell University.

Fruiting vegetables

Tomatoes, eggplant, okra and peppers are being planted outside or held in the greenhouse still until temperatures rise. Tomatoes are staked soon after planting to keep them off the ground and growing upright. There are numerous materials that tomato stakes are made from. Wooden stakes are common, which are either made from softwoods (pine, cedar, etc.) or hardwoods like oak that may be more inherently rot-resistant. Bamboo is a lightweight option but may be too flimsy to support larger plants towards the end of the season. Steel stakes can be easier to sanitize from season to season to prevent harborage of plant pathogens as well. Fiberglass stakes are typically used more in garden settings than commercial production.

While we are still a ways from the dog days of summer, it’s wise to have a plan about how you will manage the temperature in your high tunnels this season. Periods of intense heat, specifically prolonged exposure to day/night temperatures at or above 95/80 F, according to the University of Delaware, can cause pandemonium for tomato fruit set. Some varieties, like Red Deuce, will tightly curl their leaves in high heat and bright sunny conditions. The rolling itself is not a problem but can indicate heat stress that may also manifest as fruiting issues.

At these high temperatures, pollen production can drop off and the quality of the remaining pollen grains can become tacky and have low viability. Blossoms that are not pollinated fall off and fruit does not develop. On the other side of the spectrum, zippering is one issue that occurs when fruit set occurs during low temperatures. The flower doesn’t cleanly fall off, and creates a corky line, sometimes with deep holes.

Rolling up the sides and running fans is a go-to for bringing the heat down in hoophouses. But what about shade cloth? Shading can also help reduce internal tunnel temperature and cool down plants to the range of acceptable temperatures for pollination and fruit development. Many growers use 30% shade cloth on their summer tunnels. Check out this article from Purdue for more considerations when using shade cloth in hoophouse tomatoes.

Onions and garlic

Some direct seeded onions in major production regions are mostly in the one- to two-leaf stage, others are more advanced. With warm weather last week, many problematic weeds (e.g., white campion and nutsedge) took off and some await early post emergence herbicide applications for control (see photo at the end of this section). Unfortunately, cool wet weather this week makes that challenging.

White campion, purslane and barley emerging from the soil in onions. — White campion, purslane and barley windbreak in onions last week. Photo by Dan Brainard, MSU.

Carrots and celery

The aster leafhopper sweeping season is just starting. Sign up for aster yellows text alerts.

Carrot stands were developing in Oceana and Mason counties as the cold wind blew this week. Pigweed started to germinate in at least one location Michigan State University Extension visited, probably during the warmer weather last week.

Carrot seedlings emerging from the ground. — Processing carrots varied from the “rabbit ear” stage with just cotyledons to the two- to three-leaf stage in Oceana and Mason County fields this week. This was a nice stand huddling amongst a windbreak. Photo by Ben Werling, MSU Extension.

A small pigweed seedling emerging from the ground. — A small pigweed seedling. Growers are keeping an eye out for pigweed, balancing crop safety with the need for weed control. Photo by Ben Werling, MSU Extension.

For celery, as of Tuesday, May 20, aster leafhopper was present but at very low numbers in celery fields scouts had visited. Common groundsel was developing in some celery plantings, with flowering beginning and seed production not far off (see photo at the end of this section). If possible, removing flowering weeds before seedset will prevent spread and future headaches. This is particularly important in cases where weeds like groundsel that are not well controlled by common herbicides (e.g., linuron).

Common groundsel growing amongst celery plantings. — Common groundsel (Senecio vulgaris) almost setting seed in celery. Photo by Dan Brainard, MSU.

Sweet corn

Fields are being seeded continually now and transplants are being produced in the greenhouse. Black cutworm is an early-season pest that can clip young corn seedlings. The earliest plantings are most at-risk, with risk higher in fields that had heavy winter-annual weed cover, with weeds like chickweed, in late April/early May. Cutworm moths can lay eggs on the winter annual weeds at that time, with caterpillars growing and later moving to corn when it emerges. The article “Black cutworms are here” is focused on field corn but hits key points.

Strawberries

Yellow leaves on strawberry plants caused by glyphosate injury. — Glyphosate (Roundup) drift can cause sudden yellowing of strawberry leaves, particularly on newly expanded leaves and runner tips. The affected leaves typically die within a week, and plant growth may be stunted. More information on other herbicide injury on strawberries can be found in “Herbicide injury on strawberries” from Ontario.ca. Photo by Salta Mambetova, MSU Extension.

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 22, 5:30-8:30 p.m., Urban Agriculture and Policy Workshop for Beginning Farmers
May 28, Oakland County Pesticide Applicator Training
May 29, 5:30-8:30 p.m., Produce Safety Workshop for Beginning Farmers
June 5, 5:30-8:30 p.m., Soil Health Workshop for Beginning Farmers
June 10, 10 a.m.-2 p.m., AgrAbility Farm Visit in Holland
June 12, 5:30-8:30 p.m., Integrated Pest Management Workshop for Beginning Farmers
June 18 - 8:30 a.m.-12 p.m., Scouting School 2025 (Day 2)
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.

This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).

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