Southwest Michigan field crops update – July 9, 2026
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EmailMost soybeans have entered reproductive stages, and corn is approaching tasseling. Watch for western bean cutworm and tar spot in corn.
Weather
The past week was hot, humid and rainy. Precipitation over the weekend filled the soil profile and slowed down field work for the early part of the week. Temperatures are expected to increase next week. It will be a hot and dry week, with the only chance for significant precipitation occurring today, July 9, and potentially running into tomorrow.
Crops and pests
Most soybeans are in reproductive stages, ranging from R1 (one open flower anywhere on the stem) to R3 (a pod 3/16 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 light to moderate on non-irrigated soybeans in southwest Michigan for the past week.
Corn is mainly in late vegetative stages and approaching tasseling. Some early fields have started to tassel and a few seed corn fields had detasseling equipment running this week.
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.
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 over the past week, most likely brought in on recent storms. Bucket traps in Berrien (Eau Claire), St. Joseph (Centreville and Sturgis) and Van Buren (Lawrence) counties have caught the following:
|
Date |
Centreville |
Eau Claire |
Lawrence |
Sturgis |
|
6/29 |
15 |
13 |
11 |
-- |
|
7/6 |
106 |
35 |
117 |
61 |
Winter wheat is at Feekes 11.3 (hard dough) and Feekes 11.4 (harvest ready), with harvest occurring as weather permits.
Most potatoes have finished blooming and are in tuber bulking stages. Colorado potato beetle summer adults have started to emerge. The new insecticide Zivalgo is an additional chemical option for managing Colorado potato beetle. Check out the new insecticide options for Colorado potato beetle management to learn more about when and how to use it.
Alfalfa and forage cutting and baling continued over the past week.
Irrigation and water use
Corn water use continues to increase as the crop reaches peak demand. Corn at the V10–V12 growth stages is using approximately 1.0–1.45 inches of water per week.
Soybeans entering early reproductive stages are also at peak water use, requiring 1.3–1.6 inches of water per week (about 0.19–0.23 inches per day). Irrigated fields are at high risk for white mold. Monitor soil moisture and disease pressure carefully and avoid excessive irrigation, which can increase canopy humidity and favor disease development.
Potatoes in the tuber bulking stage continue to have high water demand, requiring approximately 1.3 inches of water per week.
Irrigation demand will remain high over the next couple of weeks as hot weather moves into the region. 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 6–12, 2026:
|
Crop |
Growth stage |
Constantine |
Berrien Springs |
Entrican |
Hart |
|
Reference ET |
1.32 |
1.44 |
1.46 |
1.49 |
|
|
Corn |
V8 |
0.74 |
0.81 |
0.82 |
0.83 |
|
Corn |
V10 |
1 |
1.09 |
1.11 |
1.13 |
|
Corn |
V12 |
1.32 |
1.44 |
1.46 |
1.49 |
|
Soybeans |
V4-V5 |
1.03 |
1.12 |
1.14 |
1.16 |
|
Soybeans |
R1 |
1.32 |
1.44 |
1.46 |
1.49 |
|
Soybeans |
R2 - R3 |
1.45 |
1.58 |
1.61 |
1.64 |
|
Potato |
Tuberization |
1.32 |
1.44 |
1.46 |
1.49 |
|
Potato |
Blossom |
1.32 |
1.44 |
1.46 |
1.49 |
|
Potato |
Tuber bulk |
1.2 |
1.31 |
1.33 |
1.36 |
Field Crops Virtual Breakfast Series
Irrigation management, presented by Younsuk Dong, was the topic for the MSU Extension Field Crops Virtual Breakfast this week. Evaluating irrigation system performance is an important part of irrigation efficiency. Plants in different growth stages use different amounts of water, so check fields and be aware of crop stage and evapotranspiration rates.
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.
