While there was some much-needed rain across the state last week, the rain also brought some wind with it as well that resulted in lodged or leaning corn as well as some greensnap in fields. In addition to the wind damage, herbicide injury in soybeans, tar spot concerns, and Japanese beetles were the common observations or topics of questions received by ISU Extension field agronomists. Read on for more specifics on what’s happening in different areas of the state.
Gentry Sorenson (Region 2): “Corn is in the late vegetative stages and soybeans are at the R1-R2 growth stage. On the evening of July 5, NW Iowa experienced a Derecho. A map is available to help understand the wind speed, path, and damage to property from this event. I noted lodging of corn in five counties in my region where corn plants were lodged at a 40-degree angle in fields that were affected by the storm. On July 8, I revisited some of those some fields and the corn had formed a gooseneck to become more vertical. Upon scouting, I noted some fields where greensnap was present. I would encourage those that were affected by the derecho to scout their fields to understand the level of damage to the crop. Field calls and phone calls were regarding soybean injury from post applied herbicides, questions on soybean herbicides, storm damaged corn, and questions about tar spot."
Josh Michel (Region 5): “Over the past week, most of NE Iowa has received anywhere from 1.5 to 2 inches of rainfall. Some isolated areas in Allamakee, Buchanan, and Winneshiek counties received up to 4 inches of rainfall. Most of the corn in NE Iowa continues to grow very rapidly and can be staged from V7 – V12. I’d expect to see some tassels starting to show up this week in early planted fields. I’ve received several questions about managing for tar spot. Thankfully, the weather for the next couple weeks doesn’t look conductive for tar s pot development, and producers are reminded to scout fields before making fungicide applications. Soybeans can be staged from V3 up to R2. I was able to find many fields last week that have started flowering. There’s been a few calls asking about spraying for white mold, while there’s some areas that have concerns about short soybeans on 30-inch rows that may likely not reach canopy closure. I also continue to see and hear many reports of herbicide injury on soybeans, from either tank contamination or drift injury. Over half of the oat fields that I drove by last week have started turning. In general, most of them look really good right now. Second crop harvest of alfalfa continues to get put up. Dry weather this week should allow most of it to get finished up as I continue to hear reports of potato leafhoppers and grasshopper feeding.”
East Central, Southeast, and South-Central Iowa
Rebecca Vittetoe (Region 8): “While a good portion of EC Iowa may be abnormally dry, we did get some rain events last week with totals ranging from less than 0.5 inch to some isolated areas in Johnson County getting over 5 inches. The rain also brought some wind with it too that resulted some leaning corn fields as well as some greensnap. In some of the fields there was about 2 to 5% greensnap. Corn is in the late vegetative stages, and I am starting to see some tassels showing up. Soybeans are mainly R1 to R2. Concerns and questions this last week have mainly involved tar spot, Japanese beetles, and growth regulator injury in soybeans. I also saw my first adult corn rootworm beetles out last week, both northern and western corn rootworm beetles.”
Virgil Schmitt (Region 9): “Rainfall last week in the counties I cover was extremely variable, ranging from 0.25 to over three inches, with heavier rainfall amounts generally north of the Muscatine latitude. In general, temperatures during the last week in the counties I cover were one to three degrees above normal, with the warmest temperatures south of I-80. Most corn is V13-V15 and looks good to excellent. A few fields started displaying tassels last week, and those fields are at full tassel on Monday morning of this week. Most soybeans are at V8-R2 and also look good to excellent. Japanese beetles continue to be found in all of the counties I cover. Potato leafhoppers continue to be present in alfalfa and there are some winged grasshopper adults in some grassy areas. Phone calls and field visits last week mostly involved insect identification and management and pasture weed management (mostly Canada thistle management)."
Check out the map below to find your local ISU Extension field agronomist and find their contact information here!