Regional Crop Update: June 17 - June 24, 2024

Heavy rain across northern Iowa resulted in major flooding in areas. For those dealing with flooding, additional resources can be found here ranging from farm and home to cleaning up after flooding. Read on for more specifics about what Iowa State University Extension and Outreach field agronomists saw over the last week.

Northwest Iowa

Gentry Sorenson (Region 2) “Rainfall that occurred across Region 2 was heavy, resulting in ponding and flooding. Rainfall ranged from 2 to 9 inches, streams and rivers in heavy rainfall areas have overflowed their banks leading to road closures. The city of Spencer has received extensive flooding to homes and businesses. Low lying areas that were replanted earlier in the season now have standing water that is larger than the original replant area. Resources on flooding and have been compiled at this link. The resources include information for corn, soybean, and home flooding. Field work before the recent heavy rainfall consisted of post emergence herbicide applications to corn and soybeans. Nitrogen deficiency symptoms in some corn fields can be found and iron deficiency chlorosis can be seen in some soybean fields. Corn growth stages range from V6 to V9. Soybean growth stage ranges from V1to V4. Phone calls and field calls were regarding herbicide drift, herbicide injury, nitrogen questions, and concerns about recent rainfall.”

North Central Iowa

Angie Rieck-Hinz (Region 3): “For the week of June 17 through June 24, rainfall reports ranged from 1.7 inches at Webster City to 6.09 inches at Northwood. Rainfall amounts across my northern counties refilled the ponds and generally speaking has drowned out crop that has been replanted 2 and 3 times in those ponds. Low-lying areas along rivers and streams are either flooded or will flood as the slug of water continues to drain southward along the Des Moines, Boone, and Iowa Rivers. Crop conditions vary drastically, but there are some good-looking crop in places. Corn is generally V4 to V11 and both sides of that range. Soybeans are V2 to R1. I have had no calls about insect or diseases, but I have seen a few thistle caterpillars in soybeans. With all of the recent humidity and rain now, is the time to be scouting for crop disease.  Dr. Daren Mueller just posted an ICM News article comparing rainfall and temperature this year to years with either white mold or sudden death syndrome disease prevalence, “Disease Risk in White Mold and Sudden Death Syndrome of Soybean.” Most of my phone calls and field calls are regards to herbicide issues. I fully admit, we seem to be experiencing more herbicide carryover issue than I would have expected to see this year, but I guess I should not be surprised considering how dry it was last year.”

Northeast Iowa

Josh Michel (Region 5): “Persistent rain showers came through NE Iowa last week delivering anywhere from 2.5 up to 4 inches of precipitation, with heavier amounts closer to the Minnesota border. In between rain showers, producers have been trying to complete N side dressing applications and post herbicide applications. Early planted corn fields can be staged up to V10, while later planted fields are around V4. Many fields that had wavy corn a few weeks ago are starting to even out and most fields look good. Last week I was able to find my first soybean flowers. I would expect many early planted soybean fields to reach R1 within the next few days. It’s important to check post herbicide labels for any flowering restrictions. Oats are mostly headed out and beginning to turn color in some fields. If the weather forecast becomes favorable, I would expect the second cutting of alfalfa to begin in some places. Potato leafhoppers can be found in many fields, but so far have been below threshold limits. The majority of field calls last week consisted of nitrogen management, forage management, weed identification and control, along with a couple calls about possible pesticide drift and injury in soybeans.”

Central Iowa

Meaghan Anderson (Region 7): “Central Iowa received somewhere between 1-3 inches of rainfall in the last week, which has been a great drink for the crops, especially given the extreme heat of the last several days. While the weather early last week was probably ideal for tar spot, these hot temperatures are more like what gray leaf spot prefers. Corn is rapidly reaching late vegetative stages, and I even received an image of a field with some plants starting to shoot tassels yesterday. I’ve received calls in the last week on corn rootworm, foliar disease and fungicide decisions, weed control (or lack thereof), and nutrient deficiencies, primarily sulfur, in corn. Soybeans are at beginning flower (R1) in most fields, while some are already at full flower (R2); this is the time when many herbicide applications need to finish due to label restrictions. While I haven’t seen any soybean gall midge yet this year, it is likely that they’re out in soybean fields across parts of central Iowa, along with more common insect issues like Japanese beetles. Weed control has overall looked good, but there are fields with heavy pressure that have lots of waterhemp escapes or newly-germinated individuals in both corn and soybean. With cooler weather this week, it is a good time to make a pass through both corn and soybean to look for foliar disease, weed control, and insect pressure.”

East Central, Southeast, and South-Central Iowa

Rebecca Vittetoe (Region 8): “We received some much-welcomed rain later last week with rainfall totals ranging from 0.4 to over 4 inches. Rainfall totals seemed to vary quite a bit from one neighborhood to the next. Prior to the rain you could start to see effects of the drier conditions on the crops, especially in the afternoon. The earlier planted corn is getting into the later vegetive stages, and a lot of the soybean fields are at R1 or getting really close to R1 (beginning flower). Concerns about herbicide control efficacy, herbicide injury, weed identification, potato leaf hopper, Japanese beetles, and soil compaction (sidewall compaction) where most of the calls or questions I received last week.”

Virgil Schmitt (Region 9): “Rainfall during the last week in the counties I cover was from 0.01 to 2+ inches, with the smallest amounts in the far south and the larger amounts generally to the north. Most corn is about V9 to V11 and looks good. Most soybeans are at V4 to R2 and look good. Both crops appear to have few disease or insect issues. Oats has been headed out for a few weeks and continues to look good. I hear reports of some oat fields beginning to turn color but have not observed any personally. Grasshopper nymphs are plentiful in tall grass areas. Contacts last week mostly involved weed identification, postemergence herbicides injury to soybeans, dicamba drift, and fungicide application need and planning." 

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