Regional Update: May 9 - May 22, 2023

May 23, 2023 12:57 PM
Blog Post

Planting is starting to wind down across the state as 95% of the expected corn crop and 84% of the expected soybean crop has been planted according to the May 22 USDA NASS Crop Progress Report. With planting winding down, other field activities have included herbicide applications, sidedressing nitrogen, and taking the first cutting of hay. ISU Extension and Outreach Field Agronomists share what they are hearing and seeing with how the crops are progressing and what pest and crops issues are showing up in their respective regions across the state. 

Northwest Iowa

Gentry Sorenson (Region 2) “Per the May 22, 2023, USDA NASS Crop Progress & Condition Report 97% of corn and 82% of the soybeans have been planted in northwest Iowa.  With warmer weather forecasted for the next few days it will aid in those finishing soybean planting.  Heavy rainfall was experienced in some areas of the region from May 11th-13th, leading to ponding and standing water in low lying areas. Evaluation and understanding of the effects of standing water to the soybeans growth and development and corn growth and development will be important as those areas become accessible. I have also noted grass and broadleaf emergence in some corn fields where post applications will be needed soon. Continue to scout for black cutworm as the predicted date that black cutworm will reach the 4th instar (large enough to cut corn plants) is after May 16th in NW Iowa, we should continue to scout for black cutworm until corn reaches V5.”

North Central Iowa

Angie Rieck-Hinz (Region 3): “Things have mostly dried out again and field activities resumed over the weekend of May 20-21. Corn planting is nearly complete, and corn is primarily VE to V2. Stands look good and to date very few problems have been reported. Sidedressing nitrogen has started and post-emerge weed control spraying has also started. We are getting close to wrapping up soybean planting in NC Iowa and the forecast for the week of May 22 should let us finish.  Most beans are VE-VC. Field calls have included concerns with PPO injury to emerging soybeans. It should be noted that any herbicide application is not without risk, but in these situations pounding rain increased the injury to the soybeans (Photo). When these situations happen it is important to accurately identify what you are seeing in the field as sometimes herbicide injury and seeding diseases can cause be confused. Alfalfa weevil larvae are active and producers should consider plans to cut alfalfa earlier where feeding pressure is high." 

Group 14 (PPO) injury to soybeans. Photo courtesy of Angie Rieck-Hinz.

Northeast Iowa

Alfalfa weevil larave feeding damage in an alfalfa field in Dubuque County. Photo courtesy of Josh Michel. 

Josh Michel (Region 5): “Northeast Iowa has received some timely rainfall over the past two weeks. Cumulatively, areas along Hwy 20 have received around 1.5 inches, while areas further north have received up to 3.5 inches in isolated areas. Soil temperatures continue to hover around 60°. Many herbicide applications have been taking place as weather conditions have allowed. Approximately 90% of the corn has been planted. The earliest planted fields are around V2-V3, while most of fields planted in the last 2 to 3 weeks are around VE to V1. I’ve been seeing a few fields with small amounts of herbicide injury and carryover from last year. I haven’t seen or heard of any insect damage yet, but a recent 2023 Iowa Moth Trapping Network Update, has reported significant true armyworm and black cutworm flights, prompting producers in NE Iowa to intently scout their fields. Approximately 85% of the soybeans have been planted. The earliest planted fields are at VC to V1, while the majority of fields are around VE to VC. I’ve seen some early bean leaf beetle activity, but numbers were very low. Early season soybean calls have consisted mainly of seedling diseases and possible herbicide injury. The recent precipitation has greatly helped many of the small grains and forages. Approximately 90% of the oats have emerged and they’re looking good. Pastures continue to green up and are actively growing very well. Recent pasture questions have focused on weed identification, weed management and fertilizer applications. While initially starting out slow, alfalfa fields have really taken off the past two weeks. First crop is taking place in many areas. Alfalfa weevillarave are starting to show up in many fields. Most populations have been below threshold levels, but a couple fields were cut early due to increasing numbers.”

Central Iowa

Meaghan Anderson (Region 7): “The rain seems to be on a hiatus now after bringing several nice totals across central Iowa close to a month ago; if anyone is keeping track, several counties have areas at or above average rainfall for the past 90-days, but almost everyone is far short of average rainfall for the last month. Corn and soybean planting is in the process of wrapping up, though some fields are still in the process of being planted this week. Early-planted corn is V3 to V4 and early stand assessments all things that are emerged look great for the most part. We do have some corn that sat underwater due to our early-May rainfalls and stands are short or missing in some of the prairie potholes. Most emerged soybeans are in the VC/unifoliate stage as a field, but there are some plants with the first trifoliates out. Some soybeans, particularly those planted just ahead of the rainfall on May 6-9, are seeing some herbicide injury symptoms or issues with crusting in early stand assessments. Be sure to monitor stands carefully as they emerge to determine whether filling in is necessary. Weeds are gaining size and POST sprays have started slowly in corn, which is good since I’ve seen waterhemp as tall as 3” already and it seems like grass pressure is very high this spring. Many questions in the past week have been on weed identification, herbicide issues, and replant decisions." 

Soybean seedling diseases found on soybean plants in wet areas in Central Iowa. Photo courtesy of Meaghan Anderson. 

Likely some herbicide carryover showing up in a corn field in Central Iowa.

 Photo courtesy of Meaghan Anderson. 



Southwest Iowa

Aaron Saeugling (Region 10): “Crop progress in SW Iowa is moving along at a rapid pace due to warm temperatures, dry conditions, and low wind. Herbicide applications are the most common field work this past week and will be for the next several weeks. Corn planting is estimated at 95% complete with soybean not far behind at 85%. Forage conditions have improved dramatically over the past two weeks, most cool season grasses are starting to head out. Area farmers are mowing hay this week and cows are going to grass. Long-term soil moisture may be a concern in some areas of SW Iowa where large precipitation events have missed some locations. River and creek levels are extremely low for this time of year. Isolated reports of herbicide injury prior to rain events and cool temperatures have a been a concern is small areas.”  

East Central, Southeast, and South-Central Iowa

Rebecca Vittetoe (Region 8): “Planting is winding down in EC Iowa, but other field activities going on include herbicide applications, sidedressing corn, and taking the first cutting of hay. Some alfalfa fields were harvested a little sooner than normal due to alfalfa weevil damage. If you have alfalfa and haven’t mowed it yet, I encourage you to keep your eyes out for alfalfa weevil. Corn mainly ranges V2 to V5 stage. Soybeans range anywhere from just planted to V1. There have been some concerns about uneven stands or less than ideal stands, but overall the crops are looking good. I did hear my first report of black cutworm feeding in corn, so keep your eyes open not just for cutworm, but armyworms as we’ve been seeing moth activity with both these pests. Questions over the last week have centered around alfalfa weevil, weed identification, herbicide considerations, and stand assessments." 

Virgil Schmitt (Region 9): “Rainfall in the last two weeks in the counties I cover was about 1.5 to 2.5 inches. In general, temperatures during the last two weeks in the counties I cover were one to three degrees above normal. Most alfalfa is about 26 inches tall and in the late bud stage. Mowers began operating seriously last week except even earlier in areas where alfalfa weevil was causing significant damage. Alfalfa weevil have been very active in areas generally south of Highway 92. Bluegrass and orchard grass began heading out over a week ago and smooth bromegrass is heading out now. Corn planting is mostly complete. Most corn is V2-V3 and looks good to excellent. Soybean planting is winding down. Most soybeans are un-emerged to VC look good to excellent except for areas where crusting issues have lowered populations. Some fields have had been “thicken up” with additional seeds being planted. Phone calls, emails, and field visits last week mostly involved soybean replant decisions and alfalfa weevil management options."

Rainfall totals across the state of Iowa for May 8 - May 21, 2023. Source: 

Clarabell Probasco (Region 11): “Planting progress is beginning to wrap up in south central Iowa. Approximately 95% of corn fields and 80% of soybean fields are planted. Corn can be staged anywhere from VE to V3/V4 while soybeans are anywhere from VE to V1/V2. Most of the area received moisture with the more western counties recording around 1" and up to 2" while the eastern counties only pulled in a couple tenths. Pasture and hay field growth has really taken off. Many producers have turned cattle out to pasture for the summer and have begun their first cutting hay harvest. Alfalfa fields are also being harvested in most of the territory. Some consideration for the alfalfa harvest taking place is due to the feeding pressure being seen from alfalfa weevil. The pictures below show alfalfa weevil larvae and the feeding damage to the alfalfa field. Be sure to keep an eye on your alfalfa fields to know if you are receiving pressure from this pest.”

Alfalfa plants in a SC Iowa hay field showing feeding damage from alfalfa weevil. Photo courtesy of Clarabell Probasco. 


A sweep net with alfalfa weevil larave. Photo courtesy of Clarabell Probasco.



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Rebecca Vittetoe Field Agronomist in EC Iowa

Rebecca Vittetoe is an extension field agronomist in east central Iowa. Educational programs are available for farmers, agribusiness, pesticide applicators, and certified crop advisors.

Areas of expertise include agronomy, field crop production and management of corn, soybeans, and...