Regional Crop Update: June 1 - June 9, 2020

June 9, 2020 8:46 PM
Blog Post

Sidedressing nitrogen, post emergence herbicide applications, and putting up hay were the main field activities that took place over this past week across the state. Some of the issues ISU Extension and Outreach field agronomists saw this past week ranged from dry conditions in the western part of the state, thistle caterpillars in soybeans, alfalfa weevils and aphids in alfalfa, isolated hail damage in parts of the state, and discoloration issues in corn. Read on for more information about what’s happening in specific regions across the state.

Northwest Iowa

Paul Kassel (Region 2): “The corn crop continues to develop rapidly.  Most operations are completing post emergence herbicide applications to corn and are starting in on soybean post emergence herbicide applications. Many farmers were initially confused on what to do regarding the initial court ruling made last week of vacating the labels for Xtendimax®, Engenia® and FeXapan®. The most recent announcement that the EPA will allow private and commercial applicators to spray those products this year yet according to their labels through July 31 has provided some relief and clarification. On the weather front, a recent hailstorm in Dickinson County caused damage to corn and soybean crops. Due to the damage, there is replanting of soybeans in that area.”

Corn in Dickinson County showing signs of recovery four days after a hailstorm event. Photo courtesy of Paul Kassel.

North Central Iowa

Angie Rieck-Hinz (Region 3): “For the week of June 1 through June 8, my area received anywhere from 0.25 to 2.25 inches of rain, and the heat of last week put us slightly ahead of average for GDDs for the week. Looking at a longer time period from April 1 to June 8, rainfall is below average, with Fort Dodge at -3.23 inches and Rockwell City at -3.05 inches.  Most corn is V5 to V7. I did see a corn field south of Manson on June 8 that was completely canopied.  Soybeans are V2 to V4, and I have had many comments about how slowly the beans appear to be growing.  A lot of hay was cut late last week and over the weekend. Sidedressing nitrogen was in full force and post emergence herbicide applications happened between windy days. Generally speaking, both corn and beans are looking much better with the heat. I did look at some hail damaged crops in Humboldt County from a storm that went through the evening of June 4.  Some of those acres were being replanted on June 8. Finally, since it has been one month since our frost/freeze event of May 9, here is a timeline of photos from a soybean field I have been monitoring.” 

Timeline of how soybean plants recovered from the May 9 frost/freeze event from a field near Story City, Iowa. Left: Three days (May 12) after the frost/freeze event (28 degrees), can see that the growing point is dead. Center: Photo taken on May 20, and note growth is coming from the axillary buds above the cotyledons on bean plant where the knife is located. Note also that the bean behind the knife is showing new growth at the growing point. Right: Photo taken 30 days post frost event (June 9) and note the growth is coming from the axillary buds due to death of the primary growing point.

 Northeast Iowa

Terry Basol (Region 4): “This past week has provided a good opportunity for field operations throughout NC and NE Iowa. Corn ranges from V3 to V5. You can start to see with some of the earliest planted corn the transition to the nodal roots as the primary root system. Growers have been busy in their corn fields this past week making both post emergence herbicide and nitrogen sidedress applications. Soybeans are generally anywhere from the V1 to V2 stage and are looking good throughout the area. The first cutting and harvesting of hay fields has begun in this part of the state. Rainfall accumulations varied from about 0.5 inches up to 2 plus inches in isolated areas for the past week." 

First cutting of hay being made at the ISU NE Iowa Research and Demonstration Farm. Photo courtesy of Ken Pecinovsky.

 Central Iowa

Meaghan Anderson (Region 7): “Corn and soybeans are off to the races after the warm weather last week. Most corn is between V4 and V6, while most soybeans are V2 to V3. A lot of hay was put up in the last week with a remarkably good stretch of weather for mowing and baling. Soybeans are still looking really good; stands are fairly consistent and even, with relatively few issues in them aside from some insects like bean leaf beetles and thistle caterpillars if you look hard enough. Corn has really greened up and looks a lot better than in prior weeks, though there are still some fields with unevenness and yellowing on the landscape. Yellow leaves and corn issues were a popular topic in the past week between herbicide carryover, herbicide drift, Anthracnose leaf blight, and other general yellowing of lower leaves. Corn also seemed to show more of a visual response to post emergence herbicide applications. With the completion of most post emergence herbicide applications in corn, all eyes turned to soybeans just in time for the shocking announcement of the cancellation of the Xtendimax®, FeXapan®, and Engenia® herbicide labels, though product stocks in applicator hands are available for use through July 31, 2020. The ISU Center for Agricultural Law and Taxation did a great job of covering this topic on their Ag Docket Blog. After the rainfall this week moves through, focus will turn back to those post emergence herbicide applications in soybeans, so applicators will want to assess all the options available to them (including alternatives to dicamba in Xtend crops), especially as many soybean fields approach the “no more than 45 days after planting” restriction on those labels.”

Corn showing a visual response to a post herbicide application. Photo courtesy of Meaghan Anderson.

 Southwest Iowa

Aaron Saeugling (Region 10): “Good progress was made last week and over the weekend to “catch up” on Growing Degree Days (GDDs). Moisture is a big topic of concern as we enter the later vegetative stages for corn and soybeans. Most corn is in the V5 to V7 stages and has been sprayed with post emergence herbicides. Sidedress nitrogen applications are going on corn fields now. Continuous corn fields still have a light green to yellow color due to a cool start to the season and drier conditions in the Pottawattamie and Cass Counties. There have been isolated reports of stalk borer feeding along field edges. Corn planted the week of April 20 is not much further along than corn planted the last week of April and the first week of May. First crop hay has been baled in most locations with yield lower than in past years; however, most was baled without rain damage and quality looks to be better than previous years. Most alfalfa fields had insect pressure form alfalfa weevil and/or aphids. Soybeans are in the V1 to V3 stages and have been slower growing. Scattered reports of thistle caterpillars have been the only insect reports so far in soybeans. Post emergence herbicide applications have been challenging with several windy days stopping applications. The confusion over dicamba applications on soybeans has ag retailers working with growers to make other herbicide choices for weed control. Rainfall would be a welcome relief for pastures and row crops this week for most of SW Iowa.” 

East Central, Southeast, and South Central Iowa

Rebecca Vittetoe (Region 8): “With the warmer weather this past week, the corn and soybeans have really taken off. A week ago, we were still behind on Growing Degree Days for the year, but we have really caught up in this past week on GDDs. Corn is mostly V4 to V6, with some fields at V7. Soybeans are mainly V2 to V3. A lot of sidedressing nitrogen and post emergence herbicide applications (when it was not too windy) were made this past week in corn. With post emergence herbicide applications wrapping up in corn, many are starting in on post applications in soybeans. There was a lot first cutting hay put up last week. I did get a lot of reports on alfalfa weevils and aphids as people were mowing their alfalfa fields. Other insect pests observed this past week include bean leaf beetles and thistle caterpillars in soybeans and armyworms in corn. Other than anthracnose in corn, little disease has been noted so far this year.”

Starting to see a few thistle caterpillars here and there in soybean fields. Photo courtesy of Rebecca Vittetoe.

Virgil Schmitt (Region 9): “Rainfall last week was extremely variable in the counties I cover, not only on a large scale, but from one mile to the next. Some received heavy downpours, high wind, and hail. In general, temperatures last week in the counties I cover were five or more degrees warmer than normal. Hay harvest is two-thirds to three-fourths complete. Most corn fields are at V5 to V7 and look good. However, some fields have areas where plants are yellow, purple, or showing sulfur deficiency symptoms. Most plants look otherwise healthy and color should improve as root function improves. Soybeans are mostly V2 to V3. In general, they also look good. Herbicide selection, herbicide drift, herbicide injury, and dicamba dominated calls last week.”



Josh Michel (Region 11): “Most of my region received anywhere from a quarter to one inch of rainfall over this past week. Most farmers have completed their first cutting of hay. Alfalfa weevils and aphids have been reported in several alfalfa-hay fields. Pasture productivity is quickly slowing down with the increased temperatures. Corn is developing quickly, with most fields generally around the V5 growth stage. Nitrogen sidedressing and post emergence herbicide applications have been occurring as weather and field conditions allow. Farmers should be on the lookout for corn rootworm egg hatching. Soybeans are generally at V2 to V3, and they are looking good. A lot of the replanting that occurred over the past two weeks is now emerging. Thistle caterpillars and bean leaf beetles continue to be found in soybeans, but in relatively low numbers. Field calls last week mainly consisted of herbicide applications, herbicide drift, nitrogen sidedressing, insect identification, and insect pest thresholds.”

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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...