Regional Crop Update: July 22 to July 30, 2019

July 30, 2019 9:24 PM
Blog Post

Growth regulator damage in soybeans, potato leaf hoppers, gray leaf spot, and thistle caterpillars have been some of the issues or pests ISU Extension and Outreach field agronomists have seen in fields this past week. Read on to see what is happening in specific areas across the state.  

Northwest Iowa

Joel DeJong (Region 1): “The corn for much of NW Iowa looks quite good. Yes, you can see the “sins of planting” in many fields, but the consistent rainfall so far has limited the damage. The June corn along the Minnesota border is still not pollinating, and for some it will still likely be a week before it starts to pollinate. Soybeans are at full flower (R2) to beginning pod (R3) stage. The first part of the week was filled with calls about thistle caterpillars. However, now the butterflies are again present, so we know that the second generation’s damage is mostly completed in this area. Some discussions on gall midge continue, plus a few on corn rootworm beetles, and also on corn fungicide applications with late planting. Weed escapes are becoming more visible. Green snap reports from the wind a week ago last Saturday also generated a few phone calls.”

 Southwest and West Central

Aaron Saeugling (Region 6): “On the corn side, gray leaf spot is being reported; however foliar fungicide applications in corn are starting to wrap up.  On the soybean side, while thistle caterpillar populations are decreasing, herbicide drift calls are flooding in.  Additionally, waterhemp populations continue to challenge producers in some fields. I expect late emerging populations of waterhemp to continue to be an issue until harvest.”

East Central, Southeast, and South Central:

Rebecca Vittetoe (Region 8): “EC Iowa saw little rainfall over the last week and a few of my counties are showing up as abnormally dry on the U.S. Drought Monitor. Corn ranges from late vegetative to R3 and soybeans are mainly R2 to R3. Gray leaf spot is becoming more prevalent in corn fields, but I am seeing little foliar diseases in soybeans. The second generation of thistle caterpillars in soybeans seems to be winding down. Potato leafhoppers are pretty prevalent in alfalfa fields, so take some time to scout our alfalfa. Common questions this past week have been on thistle caterpillars, fungicide applications, late-season weed escapes, and growth-regulator (Group 4 herbicide) damage in soybeans.”

Alfalfa showing severe hopper burn from potato leaf hoppers. Photo courtesy of Rebecca Vittetoe.

Virgil Schmitt (Region 9): “Rainfall last week was mostly between 0.00 and 0.25 inch with a few locations receiving as much as 0.50 inch. Corn ranges from V13 to R2. Last week I reported that there was considerable corn leaf rolling on the June planted corn due to moisture stress over the previous week’s hot days. The cooler temperatures at the beginning of this past week allowed the corn to “relax”, and when the temperatures began to rise again late last week, those fields did not return to showing signs of stress except for coarse textured or compacted soils, so apparently root growth has gotten down to more moisture. There is a little gray leaf spot. Soybeans are from R2 to R4. There is little disease pressure at this point. Group 4 injury calls and farm visits began last week and are continuing into this week. Oats are turning to turned. Pastures are turning brown. Potato leafhoppers continue to be an issue in hay. Inquiries about uneven corn, potato leafhoppers, weed management, corn fungicides, maximizing fall forage availability, and Group 4 herbicide injury on soybeans dominated calls last week.”

Rainfall totals across the state for the past seven days as of July 29. Source:

Josh Michel (Region 11): “While the temperatures were overall cooler, much of my area stayed dry this past week, with some areas receiving a quarter inch of rain. I’ve had reports of grasshoppers and also potato leafhoppers in some hayfields. Pastures have slowed down and are showing stress. Oat harvest has basically wrapped up. April planted corn ranges from R2 to R3 and the June planted corn is around V9 to V10. The June planted corn continues to show some more signs of heat and moisture stress. Early planted soybeans are mostly around R2 to R3, while later planted soybeans are around V6. Common questions this past week have been on foliar diseases in corn (common rust, gray leaf spot, and eye spot), insect defoliation in soybeans (Japanese beetles and caterpillars), managing late season weed escapes, and off-target herbicide injuries in soybeans.”

Insect feeding from a soybean field in Van Buren County. Photo courtesy of Josh Michel.

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...