Southwest Michigan field crops update – July 16, 2026
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EmailSoybeans are flowering and entering early pod formation. Tasseling started in corn, and seed corn detasseling began in earnest.
Weather
High temperatures and no precipitation made for a hot week with high water demand. Scattered showers forecast for the weekend will bring slightly cooler temperatures, with the next significant precipitation expected on Monday, July 20.
Crops and pests
Most soybeans are in reproductive stages, ranging from R1 (one open flower anywhere on the stem) to R4 (a pod 3/4 inches long at the fourth node down). Fungicide applications to prevent white mold should be applied between R1 and R3. The Crop Protection Network’s Crop Risk Tool showed high risk of white mold development on irrigated soybeans and low to moderate on non-irrigated soybeans in southwest Michigan for the past week.
More corn put out tassels this week. Detasseling of seed corn fields began in earnest. As corn enters reproductive stages, scout for tar spot by looking for small dark lesions on leaves. Make sure to add water and try to rub the lesion off. If it can be rubbed off, it is not tar spot, but insect droppings. Tar spot fungicides are most profitable when applied between R1 (silking) and R3 (milky kernel) in corn. According to the Tar Spot Map, tar spot has now been confirmed in Calhoun and Jackson Counties.
Watch for western bean cutworm in fields that are close to tasseling or freshly tasseled. Put the sun behind the leaves to watch for egg masses, which will appear as dark shadows on the backlit leaves. The threshold for western bean cutworm treatment is 5% of plants affected (cumulative week after week).
Western bean cutworm adult moth counts spiked in St. Joseph and Van Buren counties last week, most likely brought in on recent storms, and dropped this past week. Bucket traps in Berrien (Eau Claire), Branch (Union City), St. Joseph (Centreville and Sturgis) and Van Buren (Lawrence) counties have caught the following:
|
Date |
Branch 1 |
Branch 2 |
Centreville |
Eau Claire |
Lawrence |
Sturgis |
|
6/29 |
-- |
-- |
15 |
13 |
11 |
-- |
|
7/6 |
-- |
-- |
106 |
35 |
117 |
61 |
|
7/13 |
85 |
76 |
33 |
50 |
45 |
41 |
Winter wheat harvest and straw baling were in full swing the past week.
Most potatoes have finished blooming and are in tuber bulking stages. Early crop Russets are about a month away from harvest. Scout for aphids in potatoes by checking the undersides of lower leaves.
Alfalfa and forage cutting and baling continued over the past week.
Irrigation and water use
Corn has reached the VT (tasseling) stage and is now at peak crop water use, requiring approximately 1.7 inches of water per week (0.24 inches per day). The most critical period for corn extends from one week before tassel emergence through three weeks after tasseling, and water stress during tasseling and silking can significantly reduce yield potential.
Soybeans are also at peak water use (1.5–1.7 inches per week), with the greatest yield sensitivity to water stress occurring during the R3–R4 (pod development and elongation) and R5–R6 (seed fill) growth stages.
Potatoes in the tuber bulking stage continue to have high water demand, requiring approximately 1.3 inches of water per week.
Irrigation demand is expected to remain high over the next days as hot weather persists across the region. Watch for visible signs of water stress, such as leaf rolling in corn and flipped leaves in soybeans during the early morning or evening, as these may indicate inadequate soil moisture.
Stay ahead of crop water needs by monitoring soil moisture, crop growth stage, weather forecasts, and rainfall when scheduling irrigation.
To improve irrigation management, consider using irrigation scheduling tools such as the free and updated MSU Irrigation Scheduling Mobile App, available for Apple and Android devices. The app provides field-specific irrigation recommendations based on crop growth, weather, and soil type.
Weekly crop water use updates will continue to be shared through the Southwest Michigan Crop Updates. For added convenience, updates will also be sent through direct email and text messages. Sign up here. If you would like to see an additional location included in the report, please contact Angie Gradiz at gradizme@msu.edu or 531-249-4956.
The following table summarizes estimated crop water use (inches per week) for major irrigated field crops across Michigan's primary irrigated regions.
Estimated weekly crop water use for field crops in Michigan (inches/week) for the week of July 13-19, 2026:
| Crop | Growth stage | Constantine | Berrien Springs | Entrican | Hart |
|---|---|---|---|---|---|
| Reference ET | 1.5 | 1.58 | 1.16 | 1.54 | |
| Corn | V12 | 1.5 | 1.58 | 1.16 | 1.54 |
| Corn | V14 | 1.65 | 1.74 | 1.28 | 1.69 |
| Corn | VT and Silk | 1.65 | 1.74 | 1.28 | 1.69 |
| Soybeans | V4-V5 | 1.17 | 1.23 | 0.9 | 1.2 |
| Soybeans | R1 | 1.5 | 1.58 | 1.16 | 1.54 |
| Soybeans | R2 and R3 | 1.65 | 1.74 | 1.28 | 1.69 |
| Potato | Tuberization | 1.5 | 1.58 | 1.16 | 1.54 |
| Potato | Blossom | 1.5 | 1.58 | 1.16 | 1.54 |
| Potato | Tuber bulk | 1.37 | 1.44 | 1.06 | 1.4 |
Field Crops Virtual Breakfast Series
Insect management, presented by Chris DiFonzo, was the topic for the MSU Extension Field Crops Virtual Breakfast this week. Several minor pests have been sighted this season, but the next economic pest to watch for as corn tassels is western bean cutworm.
Recordings of this and all the Virtual Breakfast meetings are closed-captioned and available at the Field Crops Virtual Breakfast webpage and the MSU Extension Field Crops Team social media platforms: Facebook, Spotify, Mediaspace, YouTube, Apple Podcasts and Twitter/X.
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.
