As we approach the end of the 2025 growing season, several stressors such as the excessive moisture in July and disease pressure have accelerated crop development across the state, particularly in corn. With silage harvest either well underway or wrapping up in many areas, combines are beginning to roll through corn fields. Read on for more details about what ISU Extension and Outreach field agronomists are seeing and hearing from fields across Iowa.
Leah Ten Napel (Region 1):
Cherokee, Ida, Lyon, Monona, O'Brien, Osceola, Plymouth, Sioux, Woodbury counties
“It’s beginning to look a lot like fall as you drive around the countryside of NW Iowa! Early planted corn and soybeans are going from green to gold, silage is being chopped and combines are making their way out of the sheds. Early corn yield reports are lower than farmers expected, so it will be interesting to hear more as numbers come in. Tools like the Cligrow GDD plotter can be helpful to estimate black layer for your location and your corn maturity based on Growing Degree Days. Continue to scout fields through the fall season, paying close attention to stalk integrity as harvest gets closer!”
Josh Michel (Region 5):
Allamakee, Buchanan, Clayton, Delaware, Dubuque, Fayette, Jones, Linn, Winneshiek counties
“Over the past couple weeks most of NE Iowa has received a few light rain showers, generally resulting in 0.25 to 0.75 inch of rain. A couple isolated areas received up to 1 inch of total precipitation. Thankfully, stretches of dry weather have allowed corn silage harvest to continue mostly uninterrupted. In general, most corn fields are at R5 (half milkline) to R6 (black layer). Grain moisture has quickly started drying down in several fields, especially in some early maturing hybrids. Soybeans are generally around late R6 (full seed fill) to R7 (beginning maturity). A few early maturities are quickly turning and reaching full color. Forages continue to look good. The last cuttings of alfalfa will most likely be taking place this week as warmer temperatures should help with drying times. The majority of field calls this past week centered around pasture fall weed management, forage management and silage harvesting.”
Meaghan Anderson (Region 7):
Boone, Dallas, Jasper, Madison, Marshall, Polk, Story, Tama, Warren counties
“Central Iowa received another small shot of rainfall in the last week, though many areas received less than a quarter of an inch. Corn harvest has started, with some earlier maturity corn coming out at fairly low moistures (17-22%) and less-than-desired yields based on the early-season weather we had. I did my Polk County Corn Yield Tour on Sept. 8 and it seems that kernel counts are high, reflecting the adequate soil moisture during vegetative growth and relatively moderate conditions during pollination, but ear counts were lower than 2023 and 2024. Most corn fields looked very dry and mature, even though more than half the fields we checked were not yet at physiological maturity. More information to come on that, but farmers should be checking fields for standability now as stalks were weak in many fields. Most phone calls in the last week were about pasture weed management, southern rust, cover crops, and weeds in crops. Stay safe out there as harvest gets rolling!”
Rebecca Vittetoe (Region 8):
Iowa, Jefferson, Keokuk, Poweshiek, Washington, Johnson counties
“We went from one extreme of being excessively wet in July to the other extreme with rounding out August with below average rainfall. In the counties I cover, August rainfall totals ended up being 2 to 3 inches below average. Corn is late R5 to R6, with some fields reaching R6 prematurely. Silage chopping has been underway for a couple of weeks and over the last week, combines have started to roll in fields. I haven’t specifically heard on yield reports, but the moisture seems to range from upper 20s to some fields already under 20%. Keep an eye on stalk integrity/standability in corn fields. Soybeans are mainly R6 to R7. The pockets of sudden death syndrome in soybean fields seemed to have slowed down in expanding with the drier August conditions. Overall, forages and pastures look good for this time of year, and many are wrapping up their last cutting of hay for the year. Do keep an eye out for fall armyworms. I saw some at our Southeast Research and Demonstration Farm last week in our cover crop demonstration plots and had a couple of folks report seeing them as they were making their last cutting this past week. Now is also a good time to start thinking about fall weed management in forages as well as if you plan to do any renovations or new seedings for next year. ”
Virgil Schmitt (Region 9):
Cedar, Clinton, Des Moines, Henry, Jackson, Lee, Louisa, Muscatine, Scott counties
“In general the counties I cover received a few hundredths to 0.5 inch of rain in the last two weeks, with a few areas receiving a little more rain. Most corn is at or within a few days of R6 (physiological maturity). Some fields are completely brown. Corn silage harvest is under way. Soybeans are generally R6 to R7. Areas of soybean sudden death syndrome have declined quickly. Forages continue to look good. The last of third cutting of hay should pretty well wrap up this week. Calls during the last two weeks mostly centered around corn and soybean diseases and pasture weed management.”
Aaron Saeugling (Region 10):
Adair, Adams, Cass, Clarke, Decatur, East Pottawattamie, Fremont, Mills, Montgomery, Page, Ringgold, Taylor, Union, West Pottawattamie counties
“Well, the roller coaster just topped the hill. This crop is rapidly maturing despite excess rainfall in July and warm summer temperatures. This crop has decreased in yield potential from late July through August. Several factors are involved, from late season disease pressure in corn and soybeans to stand issues from early season stand establishment. It still is a particularly good corn crop, but I am not sure this will be a record-breaking crop across the majority of SW Iowa. Silage harvest and high moisture corn are being harvested, with yield reports coming in below previous years’ estimates. The crop is maturing too fast and dry down indicates plants are dying prematurely, which may lead to standability issues at harvest. Be actively checking moisture levels in corn to avoid any surprise grain moisture levels. Soybeans, I think, have benefited from the isolated August and September rains and in the absence of disease appear to be the better crop at this point in the growing season. Time will soon tell as leaves are dropping as the early maturity soybeans are in the R7 to R8 stage. Hay and forage production have been the big story this year with late season pastures doing well. The final cutting of hay has begun with all indications of good yields and quality.”
Logan McCrea (Region 11):
Appanoose, Davis, Lucas, Mahaska, Marion, Monroe, Van Buren, Wapello, Wayne counties
“Across south-central Iowa over this past week, there's been plenty of activity with hay being put up, silage being chopped, corn harvest underway, and cover crops being flown on, to name a few. Much of the corn crop ranges from mid R5 to R6, while soybeans mainly are R6 to R7 with some fields nearing R8. Standability in corn will be a big concern this fall, and so this early window for getting fields harvested may prove to be very valuable. Pinch test/push tests are a great way to determine potential issues and identify if some fields need prioritized over others in your harvest order. Pastures look phenomenal for this time of the year, and final cuttings of hay will be wrapping up soon. Fall management topics have been popping up lately, with forage weed management, cover crop seeding, and general fertilizer plans being a few to name. Rainfall has been lower over the past few weeks (compared to the rest of the summer), and the heat looks to turn back up later this week, so the crops will get a big push towards the finish line.”
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on September 9, 2025. The information contained within may not be the most current and accurate depending on when it is accessed.
- Field Agronomist in EC/SE Iowa