Strong storms rolled across the state again bringing more heavy rain and even some damaging wind to areas. Despite the flooding in some areas and drought in the southern part of the state, 78% of the corn crop and 76% of the soybean crop was rated in the good to excellent condition based on Monday’s USDA Crop Progress Report. Iowa State University Extension and Outreach field agronomists share what they are seeing in fields across the state.
Northwest Iowa
Paul Kassel: “Herbicide application for the soybean crop will be the main activity this week in NW and NC Iowa. Dicamba applications on the soybean crop will be challenged this year as weed size has exceeded label requirements. Off-target movement may be an issue as well due to the windy conditions that have replaced the rainy conditions of last week. Some farmers are also considering aerial application of urea to add some nitrogen to a corn crop that is showing signs of nitrogen loss. Areas of fields that have stunted corn due to the waterlogged conditions may not respond to additional nitrogen. However, corn fields with nitrogen deficiency symptoms in better drained areas of the field may respond to additional nitrogen.”
This flooded corn field in Dickinson County is typical of many corn fields in my area. Photo by Paul Kassel.
North Central Iowa
Angie Rieck-Hinz: “Corn is V8 (northern Iowa) to R1 in Story/Boone Counties. There are still a lot of ponds, and heavy rains in places on Friday have left more crop fields with standing water to fields that are almost completely submerged. Where there isn’t standing water, the corn crop looks good. I have seen some gray leaf spot, but all very minor at this point in time. There is still nitrogen being applied in some places and even urea being flown on where it continues to be too wet to get into the field. I have not seen any Physoderma brown spot, but there have been several reports of bacterial leaf streak in corn in NC Iowa. Soybeans are mostly R2, but there are some fields at R3. There were even soybeans just recently planted where pea harvest has been completed. In areas that continue to receive rainfall even, if the beans were not submerged or had ponded water, they are short, yellow and appear to be “going backwards”. Phytophthora root and stem rot is evident. The combination of small beans and lack of canopy closure along with delayed herbicide applications is causing some increased weed pressure in soybean fields.”
Septoria brown spot is starting to show up lower in the canopy in soybean fields. Photo by Angie Rieck-Hinz.
Central Iowa
Meaghan Anderson: “It seems like some parts of central Iowa cannot catch a break from the wind, rain, and even hail this year. The Saturday night storms through parts of Dallas, Polk, Jasper, and other counties have caused some significant flooding in areas that may have season-long implications. Steve Johnson, farm management specialist for central Iowa, wrote a nice post on steps to take following these flood/wind/hail events. Aside from those issues, much of the corn is starting to tassel and pollinate, and really looks good overall. Soybeans look a little tougher in some areas with soggy roots, yellow plants, and some weed pressure and volunteer corn. Keep an eye out for insects feeding on corn silks and soybean leaves, as well as gray leaf spot showing up in corn fields."
The heavy rains that feel in Central Iowa put many fields underwater. Photo by Meaghan Anderson.
Southwest and West Central Iowa
Mike Witt: “Crops in WC Iowa generally look good across the area minus some places that have drowned out due to previous flooding events. Last week’s rains were sporadic with totals in some areas of .25 inches to 3 inches in others. There were a few storms that caused damage around the I-80 corridor with some greensnap and root lodging reported. Corn is in the late vegetative stages with most fields already starting to tassel or will within the next week as they are only a few leaves back depending on planting date and maturity. Soybeans are in the R1-R2 stages, meaning blooming flowers are abundant and reproduction is occurring. Soybean fields look more patchy and ragged than corn with a lot of volunteer corn still needing to be removed. For diseases, there have been a few reports of very small amounts of gray leaf spot disease on the lower canopy of corn plants and some Septoria brown spot in the lower canopy of soybeans. Insects have not been a huge problem yet this season but farmers should remain vigilant in scouting. Post herbicide applications are continuing to occur with a few reports of dicamba damage and other issues coming in from the area.”
Southeast and East Central Iowa:
Rebecca Vittetoe: "Overall, crops continue to look really good in this part of the state. We've been fortunate to not be getting too much rain like some parts of Iowa. Some isolated areas did have some wind and green snap damage from last Thursday's storm. Most corn is tassel high by this 4th of July, with some fields already starting to pollinate. Most soybeans are in the R2 to R3 growth stage. With the warm and humid weather, we are starting to see some gray leaf spot show up lower in the corn canopy as well as some Physoderma brown spot. Common calls and questions over the past week include weed control issues, cupped soybeans, potato leaf hoppers, and gray leaf spot in corn."
Cupped soybean leaves due to off-target movement from a plant growth regulator herbicide. Photo by Rebecca Vittetoe.
Josh Michel: “Some well-timed rains fell across much of the area last week, ranging from half an inch up to two or three inches in some parts of SC Iowa. Based on the most recent U.S. Drought Monitor map that was released on June 28, most of the area is considered abnormally dry to being in a severe drought. Alfalfa fields and pastures are hanging on, but most ponds are pretty low. Overall, corn and soybean fields are looking very good. Isolated areas did see some minor lodging and green snap from the storm that rolled through last Thursday. Most corn fields have tassels poking out, and there are many fields already at R1. Soybeans are at R2 with some fields at R3. Issues and calls from this past week include herbicide drift, late season weed control challenges, potato leaf hoppers, Japanese beetles, and corn flea beetles. Recent rains have provided favorable conditions for gray leaf spot and Physoderma brown spot to start to appear in some fields.”
Corn flea beetle feeding on corn leaves from a field in Davis County. Photo by Cecil Reed.
Virgil Schmitt: “During the last week, rainfall varied from less than 0.5 inch (mostly south of Highway 30 and near the Mississippi River) to over two inches in northern Jackson County. Corn is V14 to R1 and generally looking good. There is some gray leaf spot if you look in the right place. Soybean are R2 and also looking good. Calls have centered on weed ID and management, Group 4 herbicide drift, S & K deficiency symptoms, flooding impact on crops, and Japanese beetles. Grasshopper nymphs are hopping around and katydids are singing.”
Rainfall totals as of July 2 across the state of Iowa for the past week. Source: http://www.weather.gov.
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Rebecca Vittetoe Field Agronomist in EC Iowa
Rebecca Vittetoe is an extension field agronomist in east-central/southeast Iowa serving Iowa, Jefferson, Johnson, Keokuk, Poweshiek, and Washington counties. Vitteoe works with farmers, landowners, and ag retailers to answer agronmy-related questions. Her areas of expertise include general ...