Regional Update: May 17 to May 25, 2021

May 25, 2021 10:02 AM
Blog Post

While the rain may have limited fieldwork across the state this past week, it was much welcomed in many areas that have been on the drier side. Most of the corn and soybeans that have been planted are now emerged. Two of the more common issues seen in fields this past week included alfalfa weevils in alfalfa fields and weeds getting a nice start in some crop fields. Read on to learn more about what ISU Extension and Outreach field agronomists are hearing and seeing across the state.

Northwest Iowa

Joel DeJong (Region 1): “Rainfall was spotty this past week. The southern part of my region had good rainfall with reports of 1 to 3 inches depending on your neighborhood. As you went north, the counties near the Minnesota border received well under a half inch with some under a quarter. However, I have not seen an field of corn that is not emerged (except for a few where rye silage was harvested and replanted back to corn for silage this fall), and it is rare to find a non-emerged soybean field, too. Corn is mostly V2 and V3, with enough moisture to really get the nodal roots started in fields where I have dug plants. Weedy cornfields are becoming more common. Alfalfa near LeMars measured 27 inches on Monday (May 24) morning and buds are just becoming visible. If the weather cooperated, the stage of growth for first cutting is about right for good quality hay. More alfalfa weevil injury is present, and I saw some very significant damage in an Ida County field from this pest. Rye is headed, and brome is starting to head out.”

Corn plant with three full leaf collars, putting it at the V3 stage. Photo courtesy of Joel DeJong.

Paul Kassel (Region 2): “A quick check of the weather in Spencer shows a change in the last ten days. The weather station in Spencer has received 1.9 inches of rain since May 17, which is 0.7 inches above normal.  Growing Degree Days (GDDs) since May 17 are also above normal with an accumulation of 150 GDDs. Crop development has responded. Some early planted corn in Kossuth county is approaching the V5 stage and early planted soybean are approaching the V1 stage.  Woolly cupgrass, foxtail and waterhemp are also coming to life. Postemergence herbicides have been applied to some corn fields. Pest problems have been few to date.  However, I did have a report of some seed corn maggots affecting soybean stands in Sac County.”

Seed corn maggot and damage was seen in a soybean field in Sac County. Photo courtesy of Paul Kassel.

North Central Iowa

Angie Rieck-Hinz (Region 3): “Corn is VE to V3, with a few places with larger corn.  Soybeans are VE to V1.  We had widespread rainfall across NC Iowa the week of May 17 with varying amounts from 0.69 inches at Eldora to 1.86 at Webster City.  The far northern reaches of my area finally received much needed rainfall with Northwood getting 1.08 inches the week of May 17.  Soils in areas that received lesser amounts have already dried out in the upper inch due to more heat and wind.  We are going to continue to need timely rains this growing season. I have seen very few bean leaf beetles and I have found no cutworm activity, although I have had reports of cutting.  Alfalfa weevils are active in alfalfa. Post-emerge herbicide applications have started this week in corn and I have to say it was likely too windy for applications that I saw happening this morning (5/24).  Monitor weed size now!  Because of our earlier planting dates this year, and what appears to be compromised effectiveness of our pre-emerge herbicide due to dry conditions, post application will be highly critical for weed control."

Alfalfa field in NC Iowa with a pretty heavy alfalfa weevil larvae infestation. Photo courtesy of Angie Rieck-Hinz.

Northeast Iowa

Josh Michel (Region 5): “Scattered light rain showers delivered 0.5 to 1 inch of precipitation, with some isolated areas along Hwy 9 receiving up to 1.5 inches of rainfall. Planting is around 95% complete, and emergence of both corn and soybeans continues to be slow due to cooler than normal temperatures. Stand assessments have revealed some emergence issues in several fields, especially those with moderate to high amounts of crop residue. I haven’t heard of any black cutworm feeding yet, but now is the time to be scouting for this pest. Some cold overnight temperatures from the previous week did cause some very minor leaf damage in low-lying areas, but I haven’t seen or heard of any replanting that will be needed. Alfalfa first crop harvest is starting in many areas, with reports coming in of shorter than normal yields. Reports of light alfalfa weevil feeding are also starting to come in more frequently. All planted oats have emerged and stands continue to look good. Pasture growth continues to do well with timely rainfall and cool temperatures. Recent field calls and questions have included the following: weed identification and controlling escapes, stand assessment and replant considerations, alfalfa management, and questions pertaining to frost damage to crops.”

This image captures some of the variability being observed with corn emergence in fields this spring, showing how some plants have emerged nicely and look great, whereas other plants are just emerging, and some have leafed out underground. Photo courtesy of Josh Michel.

Southwest Iowa

Aaron Saeugling (Region 10): “Crop conditions have improved in most locations in SW Iowa. Showers are hit and miss in most locations, with rainfall amounts the past week form a trace to over an inch. Moisture continues to be a long-term concern due to low subsoil moisture. Corn has emerged along with soybeans.  Most corn is V1 to V3 and most soybean are VC to V1. Some fall cereal grains are being harvested for forage. I expect hay harvest to begin late this week and yields should be good due to recent warm weather.”  

Emerged corn from a field in Montgomery County. Photo courtesy of Aaron Saeugling.

Central Iowa

Meaghan Anderson (Region 7): “Central Iowa received consistent, if small, rainfalls through the week to total something in the 0.5 to 3 inch range, depending on how lucky you were. Most crops have emerged and look quite nice, especially now that we’re getting some sun and warmer conditions. Corn is mostly in the V1 to V3 range, with the biggest corn at V5. Soybeans are mostly in the VE to V1 range. Insect issues seem fairly minimal, but crop stands are somewhat uneven and corn suffered some stand loss in many fields due to a variety of factors. Volunteer corn is prolific through the area and needs to be treated as a weed. All weeds are getting some good size on them in many fields, just in time for POST herbicide applications."

A soybean field in central Iowa with a severe volunteer corn issue. Photo courtesy of Meaghan Anderson.

East Central, Southeast, and South Central Iowa

Rebecca Vittetoe (Region 8): “Rainfall totals ranged from about 0.5 inche near Central City to 2 inches around Knoxville. The rain put a limit on the amount of field work that got accomplished this past week. Emerged corn is mainly in the V1 to V3 stage, and emerged soybeans are mainly VC to V1. I continue to get questions and concerns about uneven emergence and stand uniformity. Overall though the crops along with the pastures and hay fields are looking pretty good. Insects to be on the look out for this week include black cutworm, true armyworm, and alfalfa weevil larvae. Also as you are out scouting, pay attention to what weeds have emerged and their size. This includes volunteer corn.”   

Be scouting your fields for what weeds have emerged and pay attention to weed size. Photo courtesy of Rebecca Vittetoe. 

Virgil Schmitt (Region 9): “Rainfall last week in the counties I cover was generally 0.75 to 1.5 inches of rain, with the heaviest rains generally south of I-80. In general, temperatures last week in the counties I cover were 2 to 5 degrees above normal. Very little field work occurred last week, especially south of I-80. Corn planting is over 95% complete and soybean planting is about 75% complete, with more planted north of I-80 than south of I-80. Emerged corn in mostly V2 to V3. The most soybeans are VC to V1.I have heard of no serious insect feeding, and I really don’t expect much insect feeding, based on moth captures, but farmers should be scouting for black cutworms on all corn until it reaches V5 and also be watching for true armyworm.”

Accumulated rainfall totals aross the state this past week. Source:

Josh Michel (Region 11): “Scattered rain showers delivered around 0.5 to 1 inch of precipitation across most of the region this past week. Due to the persistent light rain, fieldwork continues to remain at a standstill in many areas. Warming temperatures are slowly helping both seedling emergence and early plant growth. Early planted corn is generally around V2 to V3, while early planted soybeans are just starting to reach V1. Hay harvest should continue as fields dry out and light alfalfa weevil damage is being reported in most fields. Oat emergence is around 95%, and stands are generally looking good so far. Pastures continue to look good as well with recent rainfall. Recent field calls and questions have centered on weed identification and controlling escapes as well as forage management.”

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


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...