Crops continue to move toward maturity in Iowa with both corn and soybeans more than a week ahead of the five-year average. Looking at the overall picture statewide, 75% of Iowa’s 2018 corn crop and 74% of soybeans are now rated good-to-excellent, both down slightly from the previous week. That’s according to USDA’s latest weekly statewide survey, released Aug. 6.
While fields of corn and beans in northern Iowa have had plenty of rain this summer, it’s a different story in the south-central and southeast parts of the state. Lack of moisture is a concern there.
Southeast, south-central Iowa remain dry
According to the U.S. Drought Monitor, southeast and south-central Iowa are experiencing prolonged heat and moisture stress. In early August, there were some two-spotted spider mites detected in some corn and soybean fields. Iowa State University Extension specialists recommend scouting corn and soybean fields for mite infestations this month, especially in these two driest areas of the state.
Iowa farmers had six days suitable for fieldwork during the week ending Aug. 5, according to USDA’s National Ag Statistics Service. Activities for the week included harvesting hay and oats for grain, spraying for aphids and moving grain.
Topsoil moisture statewide averaged 12% very short, 24% short, 61% adequate and 3% surplus. Subsoil moisture rated 10% very short, 21% short, 65% adequate and 4% surplus. Subsoil moisture levels in south central and southeast Iowa, the driest parts of the state, continued to fall with 48% considered very short.
Almost the entire 2018 Iowa corn crop has now silked. And, 55% of the corn crop has reached dough stage or beyond, over a week ahead of average. Corn in the dent stage was at 8% as of Aug. 5. Corn condition fell to 75% good-to-excellent.
Corn, bean conditions decline slightly
Looking at soybeans statewide, 94% of the crop was blooming with 81% setting pods, over a week ahead of both last year and the average. Soybean condition declined slightly to 74% good-to-excellent.
Iowa’s oat crop as of Aug. 5 was 82% harvested for grain. Second cutting of alfalfa hay is near completion. Third cutting of alfalfa hay is 30% complete, three days behind the previous year but four days ahead of average. Hay condition fell to 61% good-to-excellent last week. Pasture conditions declined to 46% rated good-to-excellent statewide. Regrowth of pastures and hay has been a concern, especially in the southern two-thirds of Iowa.
According to Justin Glisan, IDALS climatologist, much of Iowa had below average temperatures and precipitation for the week ending Aug. 5. The week started July 30-31 with unsettled weather, as widely scattered thunderstorms crossed Iowa, especially Monday afternoon and evening. At Cresco (Howard County in northeast Iowa) and Greenfield (Adair County in southwest Iowa), farmers received rainfall of 1.10 inches and 1.04 inches, respectively.
On Aug. 1, a cold front worked its way from the northwest to southeast, producing severe thunderstorms across central Iowa. There were multiple reports of one-inch diameter hail from Otho in Webster County to Boone in Boone County. Local rainfall accumulations ranged from 0.61 inch in Ames in Story County to 0.53 inch in Dubuque County.
Temps, rain below average
Statewide average high temperatures last week were generally in the lower 80s, between 2 to 5 degrees below average north to south.
Another cold front crossed the state on Aug. 2, bringing spotty thundershowers to parts of Iowa, though very little in measurable precipitation. On Aug. 3 a warm front lifted over the state, bringing warmer temperatures; highs ranged from the mid-70s to low 80s in the north and mid-80s in the southern third.
During the early morning hours of Aug. 4, an organized storm system moved into western Iowa, bringing rainfall to many stations. Sioux Center in Sioux County reported 2.02 inches, the week’s highest accumulation.
Severe weather returned on Aug. 5 as a surface front brought multiple rounds of thunderstorms along Highway 20. There were reports of hail and high winds from Webster City in Hamilton County to Dubuque in Dubuque County.
Measurable rainfall was reported at many stations across the state’s northern half, with Sheldon in O’Brien County reporting 2 inches, 1.88 inches above normal.
On Aug. 3-5, temperatures were near normal in the north and above average, by around 3 degrees, in the south. Lamoni in Decatur County observed the week’s high temperature of 98 degrees, 13 degrees above normal.