Wet, warm conditions in Michigan through April pushed some crop development ahead of schedule before a cooler trough in the jet stream arrived this week, slowing growth in many regions. MSU is pointing growers to current forecasts from Jeff Andresen and has Enviroweather app launched to deliver mobile weather and pest-model data in the field. Growers should expect variability between regions and varieties as cool nights stall warm-season growth.
Termination of winter rye and other cover crops is a concern after the early warm, wet period; high rye biomass will likely require additional passes or larger tillage equipment to prepare seedbeds, increasing diesel use and labor. Transplant health is now a central greenhouse issue and MSU Extension has released 2026 greenhouse disease and insect management recommendations; growers must follow pesticide labels and use products only for their labeled crops and uses.
Asparagus emergence varied by region and planting factors, and harvest began in southwest Michigan before a late freeze affected some stands. MSU’s emergence model — defining emergence as 25% of crowns with a spear over 1 inch — matched observed timing within a few days across locations, but cool air temperatures will slow spear elongation; average nightly temperatures between 42–50°F are commonly reported as minimums for steady spear growth. Consultants in Oceana County have found active white cutworm; permethrin is effective with a one-day preharvest interval where control is needed.
Planting and cover crops
Root crops including carrots, parsnips, potatoes, beets, turnips and radishes are being planted and are emerging on some farms, while onions and shallots are in as seed, sets and bareroot transplants. Small-seeded vegetables like carrots can suffer reduced stands when planted soon after cereal rye is incorporated; risk is higher with larger rye biomass. MSU recommends waiting roughly seven to 14 days after rye incorporation before planting small seeds, with longer waits advised when rye was dense.
Cucurbits such as zucchini are starting to go in and transplants of squash and cucumber are being hardened off; growers should be ready to deploy row covers when overnight temperatures threaten chilling injury. Brassicas and greens — broccoli, cabbage, cauliflower, lettuce and celery — continue to be transplanted, and the anticipated spring flight peak for cabbage maggot is approaching in parts of Michigan, so monitoring with the Enviroweather cabbage maggot degree-day model is advised. Cabbage maggot peak monitoring can guide timely insecticide or cultural controls.
Growers in eastern Michigan reported garlic rot and patchy overwinter survival on black plastic mulch; MSU diagnostic submissions are underway to rule out pathogens and insects. Possible contributors include late planting, cracked cloves at planting, low-level nematode or seedcorn maggot injury, herbicide carryover, and saturated soils with repeated freeze-thaw. To reduce risk in future seasons, recommendations include planting in September to early October, cracking seed within seven days of planting, improving drainage with raised beds in heavier soils, and avoiding fields with recent herbicide applications.
Greenhouse pests and products
Greenhouse tomatoes and peppers are setting fruit and beginning harvests in southwest Michigan, with early field tomato transplants being hardened off. Aphids, thrips and mites remain primary concerns because of virus transmission and chronic damage; growers have both chemical and biological options. MSU lists active ingredients with cross-over efficacy (examples include abamectin, acetamiprid, cyantraniliprole, spinetoram and spirotetramat), several biopesticides (azadirachtin, Beauveria and Metarhizium strains, mineral oils, potassium salts), and biological natural enemies (Amblyseius swirskii, Neoseiulus californicus, Orius and lacewings) that work when deployed early.
Peas are emerging on some farms and sweet corn seeding is underway statewide, with a few very early plantings already up. Covered plasticulture strawberries have largely survived recent frosts and covered plots are on track for harvest in mid-May; matted-row strawberries took some flower loss but many unopened buds remained undamaged. The spring herbicide window is closing in many plantings as preharvest intervals begin to limit some materials.
MSU Extension offers recorded webinars from the 2026 Veggie Virtual Coffee Break series on topics such as onion thrips, transplant bacterial disease management, organic fertility sources, cucurbit protection and soil steaming for high tunnels. Producers can schedule On-Farm Readiness Reviews for confidential, two-hour produce safety visits during harvest. This work is supported by the USDA NIFA Crop Protection and Pest Management Program, grant no. 2024-70006-43569.
Image credit: www.canr.msu.edu
