Regional Update: May 24 to June 2, 2021

Frost damage, uneven corn, yellow looking crops, and volunteer corn becoming more prevalent were some of the more common issues observed in fields this past week. Read on for more specifics about what ISU Extension and Outreach field agronomists are hearing and seeing across the state.

Northwest Iowa

Paul Kassel (Region 2): “Frost injury to both corn and soybean crops is the main topic this week.  Sometimes the injury is confined to a few rows near waterways or field edges.  Some continuous corn fields do have scattered frost injury across the entire field; however, much of the corn is expected to recover.  Some of it may be slow to recover since nearly all the dead leaf tissue is wrapped around the new leaf tissue.  With soybeans, the no-till fields have the most injury. Some plants will recover, but some are done. Take time this week to evaluate fields and how plants are recovering and if replanting is necessary."

Terry Basol (Region 4): “Corn is mainly V3 to V4, and soybeans VE to V1 in NW Iowa. The first cutting of alfalfa began this past week. Growers also began some postemerge herbicide applications in corn before we started receiving some welcomed rain events. We were very fortunate in our area the past couple of weeks to get some much needed rain. According to the ISU Environmental Mesonet, the Northeast Iowa Research and Demonstration Farm near Nashua received 2.06 inches of rain between May 17 and June 1. The cold temperatures late last week caused some frost damage in corn and soybeans in low lying areas, along waterways (2 to four rows in), and in no-till fields. Affected corn plants may look a little rough but should recover as their growing point is still below the soil surface. Frost affected soybeans, however, will need to be assessed in in the next couple of days to see if there is any new growth from the axillary buds. Also, it is recommended to delay herbicide applications until corn and soybean plants show signs of recovery."  

Josh Michel (Region 5): “Scattered light rain showers delivered 0.25 to 0.5 inches of precipitation across most of the region, with some isolated areas along Highway 9 receiving up to 1 inch of rainfall. Overnight temperatures near freezing have resulted in light frost damage to corn and soybeans in low-lying areas and areas that have moderate to high levels of crop residue. Stand assessments should be conducted in order to determine if any replanting is warranted.  Early planted corn is mostly around V4, while soybeans are generally around V1 to V2. The first crop of alfalfa is well under way, with many reports coming in of average to slightly below average tonnage, due to cooler than normal temperatures throughout most of the spring. Oats continue to look good, with some early planted stands starting to head out. 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 assessments and replant considerations, alfalfa management, and questions pertaining to frost damage to corn and soybeans.”

Southwest Iowa

Aaron Saeugling (Region 10): “Thankfully SW Iowa didn’t experience the frost like other parts of the state did last week. Most soybeans are in the V1 to V2 stage and look good. I did get my first notification from across the river in Nebraska that soybean gall midge adults are starting to emerge. So if you have fields that have been impacted before by this pest, you should be on the lookout for soybean gall midge. Corn has been the crop generating the most questions this past week with the most common question focusing on the variability in corn height. The cause for this variability can only truly be assessed on a field to field basis. While sometimes it may be a planting depth issue other times it goes back to the drier conditions at planting and inconsistent moisture. Consequently, seeds didn’t all absorb water and start germinating at the same time. Additionally, the cooler conditions didn’t help and has slowed growth. To illustrate, during the week of May 8 to May 14, we only accumulated 43 GDDs. On the forage side of things, the alfalfa crop conditions are vastly improved from just a few weeks ago. However, the one big challenge now is that insect damage was more severe than first thought.  Most alfalfa is being cut now with yields variable based on alfalfa weevil, aphid or lygus bug damage. I have also received reports of poor-quality stands. Pastures are in better shape due to some May rainfall and cooler than normal temperatures. Let’s hope for some much need June rainfall to replenish sub-soil moisture.”

Central Iowa

Meaghan Anderson (Region 7): “Central Iowa got another week of mostly moderate temperatures and some rainfall to bring our total rainfall in the last 60 days to mostly in the 4 to 6-inch range. While some of my area, like southern Madison and Warren Counties are >75% of normal rainfall for that timeframe, most of my area is 25-75% of normal. Corn is mostly in the V4 to V6 range now and soybeans are in the VC to V2 stage. This week of warmer weather and sun will be good for crop growth (and getting rid of that yellow tint on corn & soybeans!) and postemergence herbicide spraying. Most of my area missed significant affects from the frost late last week, but some of my more northern territory (north of Hwy 30) did catch frost. Much of the corn in central Iowa has some silver leaf appearance due to the cold temperatures last week. Corn is still quite uneven looking in many fields due to variable seeding depth and emergence timing, but many soybean fields are looking excellent. Volunteer corn continues to be more evident in many fields and will need treated soon! Recent phone calls have been on herbicide injury to crops, cold temperature effects, POST herbicide treatments, and weed identifications.”

East Central, Southeast, and South Central Iowa  

Rebecca Vittetoe (Region 8): “The sunshine and warmer temperatures this week are much welcomed. Many either have or are planning to take their first cutting of hay this week. Corn is mainly in the V3 to V5 stages, and soybeans range from VC to V2. The northern part of my area is seeing some frost damage in corn and soybeans. Low-lying areas, the first couple rows next to waterways, and no-till fields have the most damage. The corn should grow out of it since the growing point would still have been underground. We should start to see some new regrowth on soybeans here in the next day or so if they are going to recover from the damage. Besides the frost damage, the other big observations and issues this past week included unevenness in corn fields, yellow looking crops, herbicide injury, and volunteer corn become more and more prevalent in fields (plan to treat soon)."

Virgil Schmitt (Region 9): “Rainfall during the last eight days in the counties I cover was generally 0.75 to 3.0 plus inches of rain south of I-80 and 0.5 to 1.5 inches north of I-80. In general, temperatures during the last eight days in the counties I cover were 1 to 3 degrees below normal. Very little field work occurred last week, especially south of I-80. Corn planting is for all practical purposes complete north of Highway 92 and about 95% complete south of Highway 92. Soybean planting is about 95% complete north of Highway 92 and about 75% complete south of Highway 92. Corn is mostly V4 plus or minus one collar. Most soybeans are VC to V2. Hay mowing began in earnest on Sunday and continued on Monday and Tuesday. Many are reporting that the hay is shorter than normal for first cutting. Calls last week centered mostly around weed management, herbicide injury, and yellowish corn.”

Josh Michel (Region 11): “Rainfall totals ranged mainly from 0.25 to 0.50 inch this past week with some isolated areas along Highway 2 receiving closer to 1 inch of rain. Farmers were able to get a couple days of fieldwork done between rain showers last week.  Corn is generally around V1 to V2, with early planted fields around V4. Soybeans are generally still emerging, with early planted fields around V1 to V2. The first crop of alfalfa harvest is well under way as fields continue to dry out.  Oats continue to look good, with early planted stands starting to head out. Pasture continue to grow well with timely rainfall. Recent field calls and questions have centered on weed identification and controlling escapes, stand assessments, as well as forage management.”

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