Regional Crop Update: Aug. 26 - Sept. 9, 2024

As the 2024 growing season winds down and as we gear up for harvest, check out what the ISU Extension and Outreach field agronomists are seeing in their regions across the state.  

Northwest Iowa

Leah Ten Napel (Region 1): “Rainfall in the last 2 weeks has varied across my region of NW Iowa. Some areas accumulated almost 2 inches, while other areas received only 0.2 inch over the 14-day period. Areas with less moisture and lighter soils are starting to dry down quickly. Most corn is in the dent to black layer stage. Soybeans stages range from beginning seed to beginning maturity. Disease and insect pressure are staying relatively low in soybean fields. I am seeing some soybean gall midge damage in fields where it has been identified in the past. Corn fields have more disease present. The most common is southern rust. Weed issues are present in both corn and soybean fields. Challenges with short application windows, flooding and chemical resistance all impacted weed control this year. Silage harvest has been in full swing and will continue throughout this week. Tonnage is looking good. Standability will have a big impact on harvest timing this year. Two tests can be used to evaluate standability:

1. “Pinch test”
   • Check stalk firmness by pinching the lower internodes near the ground between your thumb and forefinger
   • Be concerned when: stalks crush easily
2. “Push test”
   • Push the plant at shoulder height approximately 30 degrees from vertical
   • Be concerned when: plants pinch over, plants fail to snap back to vertical

If more than 10% of plants in a field crush easily or lodge, this indicates stalk rot may be an issue, and that field should be prioritized for harvest."

North Central Iowa

Angie Rieck-Hinz (Region 3): “Rainfall from September 1 through September 9 has totaled 0.03 inches at Webster City to 0.64 inches at Northwood.  Normally we average around 1 inch of precipitation for that time period. When I look at rainfall from August 1 through September 9 we are 3.18 inches below average at Iowa Falls and 1.96 inches above average at Northwood. The predicted heat of this coming week, along with moisture stress will finish off a lot of the crop in NC Iowa.  Pastures are thin and turning brown and likely not to recover for fall grazing. There is hay cut at this point in time, silage harvest has started, and there is even some corn being harvested. Corn is R5.5 (milk line is 50% down the kernel) to R6 physiological maturity. Soybeans are R6 (full seed) to R7 (beginning maturity). It is amazing to see a prevalence of Southern rust in corn in NC Iowa, which is a bit of an oddity.” 

Northeast Iowa

Josh Michel (Region 5): “Over the past two weeks most of NE Iowa received anywhere from just over 1 inch of rainfall, up to 2.5 inches in isolated areas. Despite the rain, farmers have been able to stay caught up on the current alfalfa harvest. Recent regrowth and pastures have benefited well from the rainfall. Warm temperatures are pushing corn and soybeans to maturity. Corn is mostly R5.5 to R6, while most soybeans are anywhere from R6 to R8. Corn silage harvest has been ongoing now for the past couple weeks, and I’d expect that most fields should be completed within the next 7 to 10 days. Stalk integrity is a concern as some fields may be ready for grain harvest within the next 2 to 3 weeks.”

Central Iowa

Meaghan Anderson (Region 7): “All of my central Iowa counties received some rainfall in the last two weeks, mostly in the 1-2 inch range. Corn ranges from early dent (R5) to mature (R6). Yield expectations are good overall, but I expect there will be a lot of variability. Now is a great time to check those fields in the R5 stage and check out what the ear leaf and the upper canopy looks like from a foliar disease standpoint, do the “push” test to make sure stalk rot isn’t setting in, and do some yield checks yourself. We had numerous hail pockets during reproductive stages, so those fields may be more likely to have ear rot or other issues that are good to scout for ahead of harvest. Soybeans are anywhere from R6 (full seed) to R8 (mature). Fields are maturing variably, with some areas that were under more stress or had disease pressure maturing faster. Weed pressure is apparent in some fields, with waterhemp and foxtails as the most common species. Silage and seed corn harvest is in full swing, and I expect to see harvest of field corn and soybean get started in the next week. Make sure your grain bins are in good shape prior to harvesting the new crop; check out this article for more information!”

East Central, Southeast, and South-Central Iowa

Rebecca Vittetoe (Region 8): “Rainfall in my region of the state the last two weeks ranged from just shy of 0.6 to over 2.8 inches. Most of that rain came the very end of August with the first part of September being rather dry. Crops are moving right along with corn ranging from R 5.5 (half milk line) to R6 (black layer) and soybeans from R6 (full seed) to R8 (mature). Tar spot is quite prevalent in some fields, especially earlier planted corn fields. Standability in corn is going to be a concern this year based on what I’ve seen in some corn fields. Take time to evaluate standability in your corn with the pinch or push test. In addition to corn silage harvest going on, I have seen just a hand full of corn and soybean fields be harvested. I expect it will be another couple of weeks before harvest is in full swing. As we gear up for harvest, here are some good reminders to have a safe harvest! On the forage side of things, while my fall armyworm calls have died down, I have noticed some egg masses and have also had reports of armyworm egg masses, so continue to keep an eye out for this pest in the coming weeks.”  

Virgil Schmitt (Region 9): “Rainfall during the last two weeks in the counties I cover was from 1.0 inch to about 4.0 inches, with the heavier amounts generally in Muscatine County and lesser amounts with distance from Muscatine. Most corn is mid-to-late R5 and looks good. Corn silage harvest is in full swing. Most soybeans are at R6 – R8 and look good. Most fields have leaves that are starting to senesce. Pastures look good. Contacts last two weeks mostly involved weed management, herbicide resistance, and forage seeding and improving.”

Check out the updated map below to find your local ISU Extension field agronomist and find their contact information here!