Dry conditions continued in Iowa last week, with half of the state rated short or very short on topsoil moisture. Iowa received only scattered reports of rain for the week ending July 30, according to USDA’s latest statewide survey.

Corn conditions in Iowa declined to 10% poor to very poor, 25% fair, 52% good and 13% excellent. Soybean conditions decreased slightly with 12% rated poor, 28% fair, 51% good and 9% excellent. “Much of the state remains very dry with farmers looking for a good soaking rain as we enter August. August is a critically important time for soybeans,” points out Iowa Secretary of Agriculture Bill Northey.

South-central, northwest Iowa are driest
Parts of south-central Iowa were under severe drought conditions last week. In south-central, 98% of the topsoil was rated short to very short on moisture as of July 30. Topsoil was 89% short to very short in southeast Iowa, and 83% short to very short in northwest Iowa.

“The rainfall we’ve had this summer has been very spotty,” says Rebecca Vittetoe, Iowa State University Extension field agronomist who covers south central Iowa. “We are definitely seeing stress on the corn from lack of moisture and from excessive heat, here in areas of south-central and southeast Iowa.”

Ears aren’t fully filling out with kernels
“Most of the fields I’ve been in have hit the nick for pollinating,” Vittetoe says. “The pollen was out there and so were the silks in time to catch it during pollination in July. But I’ve now started to notice, as I’ve gone back to check the ears for kernel fill, I’m seeing some of the kernels starting to abort. I’m seeing some tipping back of kernels on the ear. That is, ears aren’t filling out all the way to the ear tips. It varies from a little bit of tipping back on some ears to no kernels half way down the ear.”

Two weeks ago, Vittetoe began seeing “firing” of plants in cornfields. Corn plants started losing leaves near the bottom of the stalk. Plants in driest areas are sacrificing those leaves in an effort to stay alive. Usually, firing shows up along field borders first and then outside rows. Other issues aggravate it. “If there is any corn rootworm feeding or soil compaction, those are places in a field where firing shows up,” she says. “Also in sandy spots, where soil doesn’t have much moisture holding capacity, you’ll see firing.”

Some cutting droughty corn for silage
Last week Vittetoe had quite a few phone calls from farmers wanting to harvest their crippled corn crop as silage and feed it this summer, instead of leaving the crop in the field to produce grain.

“It’s pretty sad in some areas,” says Vittetoe. Most areas didn’t get much if any rain last week. ISU Extension is organizing drought meetings for farmers in south-central and southeast Iowa. The meetings will be held next week. “Also, at ISU’s McNay Research Farm Field Day on Aug. 2, we will discuss drought-related topics,” she adds. “We changed the format for that field day; we’ll cover drought-related topics as well

The complete weekly crop and weather report is available on the Iowa Department of Agriculture & Land Stewardship’s website IowaAgriculture.gov or on USDA’s site nass.usda.gov/ia. The report summary follows.

Summary of Iowa crop conditions
Iowa remained mostly dry with scattered reports of rainfall during the week ending July 30, according to USDA’s National Ag Statistics Service. Statewide there were six days suitable for fieldwork. Activities for the week included applying fungicides and insecticides, harvesting oats and haying.

Subsoil moisture 19% very short, 31% short
Topsoil moisture on average statewide rated 22% very short, 31% short, 45% adequate and 2% surplus. South-central Iowa reported two-thirds of topsoil moisture as very short. According to the July 25 U.S. Drought Monitor, parts of south-central Iowa were considered under severe drought conditions. Subsoil moisture as of July 30 fell to 19% very short, 31% short, 48% adequate and 2% surplus as a statewide average.

Statewide, 91% of Iowa’s corn crop has reached the silking stage, three days behind last year but five days ahead of the five-year average. And 19% of the corn crop has reached the dough stage, four days behind last year and two days behind average. Corn condition declined to 2% very poor, 8% poor, 25% fair, 52% good and 13% excellent.

Corn, soybean condition declined last week
Soybeans blooming reached 85%, four days behind last year but one day ahead of average. Soybeans setting pods reached 52%, two days ahead of average for the state. Soybean condition decreased slightly to 3% very poor, 9% poor, 28% fair, 51% good and 9% excellent. Iowa’s oat crop as of July 30 was 73% harvested (for grain or seed), one day ahead of average.

Second cutting of alfalfa hay reached 95% complete, four days ahead of last year and nearly two weeks ahead of average. Third cutting of alfalfa was 22% complete, one day ahead of average. Hay condition dropped to 54% good-to-excellent; pasture condition was rated 37% good-to-excellent. Reduced temperatures improved livestock conditions; however, supplemental feeding of hay and rotation of pastures were reported due to lack of rain causing poor pasture conditions in a widening area of the state.

Weather summary for Iowa
Harry Hillaker, state climatologist with the Iowa Department of Ag and Land Stewardship, provides the following weather summary for the week ended July 30.

It was a mostly dry week across Iowa with seasonal temperatures. The week’s only rain came July 26 when showers and thunderstorms covered most of the state. The most widespread rains fell across about the western one-third of the state, plus far eastern portions of Iowa. No rain fell over portions of central and south-central Iowa at such locations as Waterloo, Marshalltown, Grinnell and Fairfield. Mount Pleasant recorded the most rain with 2.20 inches, while Denison and Schleswig in Crawford County both picked up 1.90 inches. The statewide average rain amount was 0.36 inch, while normal for the week is 0.95 inch.

July 2017 ranks third driest July in past 25 years
Temperatures for the week averaged 1 or 2 degrees above normal over the southwest portions of Iowa and 1 or 2 degrees below normal across the northeast, with a statewide average of 0.3 degree below normal. Weekly temperature extremes varied from a July 25 afternoon high of 97 degrees at Sioux City to lows of 51 degrees at Cresco on July 29 and Lowden on July 30.

Preliminary data suggest a statewide average temperature for July 2017 of 75.1 degrees or 1.5 degrees above normal, while precipitation averaged 2.89 inches or 1.61 inches less than normal. This ranks as the 38th warmest and 41st driest July among 145 years of records for Iowa. Only 2012 and 2013 brought less July rainfall to the state among the past 25 years. Preliminary monthly rain totals varied from 0.41 inch at Pocahontas to 13.88 inches at Guttenberg, where this was the highest rain total for any month at that location among 86 years of records.