Iowa Field Reports: Moisture Stress – Too Much or Too Little

    Drought stressed corn.

    Isolated hail and wind damage, iron deficiency chlorosis, herbicide damage, and moisture stress (too much or too little depending upon the area) were some of the big issues that ISU Extension field agronomists noted in fields across the state. Read on to for more specifics about what’s happening in different areas across the state.

    Northwest Iowa

    Gentry Sorenson (Region 2): “Corn growth stage is at V6 to V7 and soybean growth stage is V2 to V3.  Rainfall information gathered from the Iowa Mesonet shows light precipitation totals for the week with most areas under a ½ inch to a trace. The largest rainfall amount was in Kanawha with a total of 1.1 inches.

    “With the high heat during the daytime, I am seeing some areas of corn rolling its leaves. Field work consisted of POST herbicide application to soybeans and baling the first crop of hay.  In fields with high pH areas, soybean are exhibiting IDC (Iron Deficiency Chlorosis). Phone calls and field visits consisted of general post herbicide questions, herbicide drift, and questions about insects.”

    North Central Iowa

    Angie Rieck-Hinz (Region 3): “For the week of June 13 through the 19, NC Iowa had anywhere from 0.65 inches of rain to 3.8 inches of rain, with local heavier amounts of 4.5+ inches. Another hail event occurred on Tuesday the 14th in the Hubbard area.

    “For the most part it does not seem like a lot of crop was replanted in the Boxholm to Gowrie area from the prior week’s hailstorm due to wet soils. Corn is V3 to V9 and soybeans are V2 to V5.  Generally speaking, unless there is drowned out crop in the potholes, the crop is looking good. Iron deficiency chlorosis (IDC) started showing up last week in soybean fields on high pH soils.

    “The majority of phone calls this past week have been about herbicide drift onto alfalfa and soybeans, nitrogen sidedressing questions, and inquiries to herbicide options if dicamba can’t be applied by June 20.”

    Northeast Iowa

    Terry Basol (Region 4): “Corn and soybeans are looking really good in the area. Corn fields range anywhere from V4 to V7, and with the warm weather, they are starting to stretch their “legs”, especially due to the relatively full moisture soil profile we have for NC and NE Iowa. Strong winds have depleted some of the surface soil moisture.

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    “With the wind and warm temperatures combined, we will still need timely precipitation events to continue through the growing season. Pretty much all the corn has been sprayed with a POST application, and growers are working hard to get the planned sidedress nitrogen applications completed before the corn gets too big. For some fields, we’re starting to see canopy closure. Soybeans range from VC to V2 for the area.

    “Growers are working hard to get timely applications of POST herbicide applications completed, which has been challenging due to the strong winds and isolated areas in which we have had excessive amounts of rainfall (ranging from 4 to 6 inches from one storm event).  Corn rootworm larvae hatch is right around the corner.

    “As a rule of thumb, 50% of egg hatch occurs between 684-767 accumulated GDDs (since January 1; base 52°F, soil). Currently as of June 20, 2022, we’re at 672 accumulated GDDs at the Northeast Iowa research and demonstration farm near Nashua according to the Iowa Mesonet.

    “Regarding how our area is doing for accumulated GDDs for the 2022 growing season (derived from the Iowa Mesonet), we’re right on track (slightly above) in comparison to the 30 year average (May 1 – June 21, 2022). As far as precipitation, according to the Iowa Mesonet, the NE IA Research and Demonstration Farm here at Nashua has received 1.44” of rain for the period of June 6 to June 19.”

    Josh Michel (Region 5): “Post-emergence herbicide applications and fertilizer sidedressing applications continued to be the main activities being conducted last week. Over the past week, most of the region received anywhere from 0.10 to 0.50 inch of rain, but some isolated areas in parts of northern Winneshiek County received up to 2 inches of rain.

    “Additionally, last Wednesday, some isolated thunderstorms rolled through parts of Buchanan County delivering up to 2 inches of rain, accompanied by some strong winds and small hail. Thankfully, scouting the next morning revealed very little damage to any corn and soybean fields.

    “Most of the corn in NE Iowa can be staged from as small as V1/V2 up to V7 in some early planted fields. Many fields have been receiving POST herbicide applications as well as some sidedressing fertilizer applications. True Armyworms continue to be a pest in isolated fields. Soybeans can be staged from V1 up to V4. Like corn, many soybean fields have been receiving POST herbicide applications.

    “Many fields of oats are headed out and continue to look good so far. Alfalfa first crop harvest has finally been finished up. The new alfalfa regrowth is looking good so far. Pastures continue to look good, even though warm temperatures have started slowing down many of our cool season grasses.

    “Recent field calls and questions have consisted mainly of weed management, herbicide applications, small grains and forage management, and questions about managing insect pests.”

    Central Iowa

    Meaghan Anderson (Region 7): “Central Iowa is a tale of two dramatically different scenarios yet again this summer, with the northwestern portion of my area receiving significant rainfall in the last week and much of the area to the east and south receiving very little or none; this is a trend that seems to be persisting and will be something to watch as we approach reproductive stages in corn and soybean.

    “Crops are developing quickly, with corn ranging from V4 to V8 and soybeans mostly ranging from V1 to V4. Many fields in the wetter portion of central Iowa have drowned out spots or ponds that are still drying/receding and general wet field conditions, making timely POST herbicide applications a big challenge.

    “As POST herbicide applications wrap up, I expect to hear more about herbicide injury concerns and areas of poor weed control. Questions over the last week have been on herbicides, herbicide injury, seedling disease, and weed identification.”

    Southwest Iowa:

    Aaron Saeugling (Region 10): “Wild June weather continues to impact some locations in SW Iowa. We had high winds and building damage in the Pottawattamie and Mills counties last week. Replanted crops are making good progress and the hailed off corn has started to grow and look better.

    “Unaffected areas are more on pace with normal crop growth and development and are now shading the row and look good. Pasture conditions deteriorated over the past week in areas that have not received rainfall in the last 10 days due to high temperatures and high wind conditions. Grass hay is being put up and appears to be in good condition.

    “Herbicide applications continue to be the primary activity with soybean weed control the primary target.”

    East Central, Southeast, and South-Central Iowa:

    Rebecca Vittetoe (Region 8): “Overall, crops look good in EC Iowa. Corn is mainly in the V4 to V8 growth stage and soybeans V3 to V5. With the heat last week and into this week, I have noticed some corn fields where plants are rolling their leaves in the afternoon, particularly on sandier soils or more compacted areas in fields.

    “We did receive rainfall last week with totals ranging from a trace to less than 1.0 inch across the area. Although we’ve been catching rains, we are an inch below normal for the month of June and since April, EC Iowa ranges from approximately 2.5 to just shy of 5 inches below normal rainfall.

    “Field activities last week mainly consisted of herbicide applications, some sidedressing, and putting up grass hay. The main concerns or questions I got last week involved POST herbicide applications, herbicide injury and herbicide drift.”

    Virgil Schmitt (Region 9): “Rainfall last week in the counties I cover was extremely variable, ranging from a trace to about 1.5 inches. In general, temperatures during the last week in the counties I cover were four to seven degrees above normal. Most corn is V6 to V8 and looks good to excellent.

    “Some yellow flag leaves are showing up, known as rapid growth syndrome. POST herbicide spraying is pretty well wrapped up. Most soybeans are at V3 to V4 and also look good to excellent. I have not seen any blossoms yet. A great deal of post emergence spraying occurred last week. First cutting hay harvest is wrapping up.

    “Some ditches are being mowed. According to the Iowa Administrative Code, in most cases, ditch mowing should not occur between March 15 and July 15 to allow bird nesting to near completion. Phone calls and field visits last week mostly involved herbicide injury and herbicide drift.”

    Clarabell Probasco (Region 11): “Rainfall was received across the region, with some places having much more than others. The northern counties only caught a few tenths, whereas some areas of the southern counties recorded anywhere from 0.5 of an inch up to 2.5 inches.

    “The week was full of very warm temperatures which helped crops accumulate some growing degrees that we may have lacked in the beginning stages of development. Corn and soybean fields are continuing to develop well across the area. With the warm temperatures, many growers have had a good run on getting their hay crop harvested.

    “Throughout the area, there have been many sidedressing and top-dress applications of corn fields as well as POST herbicide applications being made. Continue to scout fields for any insect pressure that may be seen, such as stalk borers or Japanese beetles.”




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