Regional Crop Update June 18 to June 26, 2018

The saga continues with areas of northern Iowa receiving too much rain while southern Iowa continues to be on the drier side. Rainfall totals across the state ranged anywhere from nearly 10 inches in NW Iowa to less than half an inch in parts of southern Iowa. According to Monday’s USDA Crop Progress Report, 81% of Iowa’s corn crop and 79% of Iowa’s soybean crop is rated in the good to excellent condition. Check out what Iowa State University Extension and Outreach field agronomists are seeing in fields in NW, WC, EC, SE, and SC Iowa.   

Rainfall totals across the state of Iowa as of June 25th for the past week. Source: http://www.weather.gov. 

Northwest Iowa

Paul Kassel “Heavy rains were the main topic of discussion last week. Almost all of my area received between 4 to 5 inches of rain since June 20.  Most of that rain fell in areas that were already saturated. The exception is the southwest corner of Buena Vista County where rainfall amounts have been almost ideal this spring. Field work continues to be at a standstill. Weed control in the soybean crop will be a compromise since weed size has been exceeded for almost all postemergence herbicides. The good news is that the preemergence applications have worked very well. Corn development looks good in the well-drained fields. There is some corn that was planted on April 30 that is at the V12 stage, is 4 feet tall and is predicted to start tasseling on July 6.”

This Clay County soybean field is showing stress from water logged conditions. Photo by Paul Kassel. 

Southwest and West Central Iowa

Mike Witt “This week in West Central Iowa rain is the name of the game. Flooding issues will impact yields this year, but it is too early in the process to make a good assessment. Corn generally is looking good and is in the late vegetative stages with a few tassels showing in the area. Soybeans are mostly in the R1 and R2 stages which means blooming is occurring. Nutrient issues such as Nitrogen deficiency or general yellowing from water will show up with the rain patterns and wet areas in the fields. Japanese beetles are starting to show up in fields in west central Iowa so be aware of them and damage they can cause. Overall crops are handling the rain and flooding issues the best they can. Once things dry out a bit there will be more evaluations to do as far as weeds, nutrients and blank field hole filling in.”

Southeast and East Central Iowa:

Meaghan Anderson: “Corn is in late vegetative stages and looking beautiful across most of east central Iowa. Many fields will likely begin to shoot tassels this week, and agronomists will be keeping an eye out for diseases like gray leaf spot. Given the recent rainfalls, Physoderma brown spot may be showing up in corn as well. Soybeans are flowering across much of the area, with many fields already at R2.  Phone calls in the last week have continued to include potassium deficient corn and herbicide issues in both corn and soybean. Dicamba injury phone calls in soybeans have started and will likely continue over the next several weeks.”

A good reminder to pay close attention to what traits are planted where and where what herbicides get sprayed. Here is some glyphosate tolerant corn that was accidently sprayed with Liberty or glufosinate instead. Photo by Meaghan Anderson. 

Herbicide group 15 injury in a soybean field that was mistaken for dicamba injury. Photo by Meaghan Anderson. 

A known infested field of Palmer amaranth in EC Iowa. This is a good reminder that when out scouting to double check any suspicious looking plants. Here's a handy resource for identifying Palmer amaranth. Photo by Meaghan Anderson.  

Rebecca Vittetoe and Josh Michel: “Based on the U.S. Drought Monitor much of SC Iowa is considered to be in either a moderate or a severe drought. Thankfully, some much needed rains fell last week and over the weekend, with rainfall totals ranging from half an inch to over two inches of rainfall. Alfalfa fields and pastures are looking good with the recent rains, but many ponds are still low. The warmer summer temperatures are slowing forage growth, which we often call the summer slump. Overall, corn and soybean fields are looking very good.  Most corn fields are at least V14, with some fields already starting to show some tassels. Soybean fields are pretty much all in the reproductive stage, being either at R1 or R2. Common issues seen this past week include potassium deficiency, herbicide issues, weed control challenges, potato leaf hoppers, and Japanese beetles. With the recent rains, gray leaf spot is also starting to show up on the lower leaves in some corn fields. Take some time to scout fields this week and see how your post herbicide application is working and check for any potential disease or insect issues.”  

Warm and humid weather provides favorable conditions for gray leaf spot to develop. This gray leaf spot lesion was found lower in the canopy in a corn field in Washington County. Photo by Rebecca Vittetoe. 

Virgil Schmitt: “Over the last week, most of my territory received 2 – 3 inches of rain, with some spots receiving 5+ inches and some spots between 1 and 2 inches. Corn is mostly V12 plus or minus a leaf and is generally looking good. Soybean are mostly R2 and also looking good. Dicamba drift, potassium deficiency symptoms, sulfur deficiency symptoms, glyphosate resistant waterhemp, Japanese beetles, poor soybean emergence, herbicide carryover, and spray equipment contamination dominated calls last week.”

Check out this map to find your local ISU Extension and Outreach field agronomist here!