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Column: Crop Watch - Iowa corn badly damaged by windstorm; widespread rain still needed

SIOUX FALLS, S.D. (Reuters) - Yield potential for Iowa corn took a nosedive after the damaging windstorm, or derecho, swept through last Monday. Otherwise, it was another relatively dry week for the U.S. Crop Watch corn and soybeans, including those in Iowa.

The sun lights a corn field waiting to be harvested near Akron, Iowa, U.S., October 28, 2017. REUTERS/Lucas Jackson

Expectations also declined last week in North Dakota and Nebraska, which need rain urgently, although many of the Crop Watch fields have needed rain for some time now. Temperatures should remain favorably cool over the next week, but the precipitation forecast is sparse.

Crop Watch 2020 follows one corn and one soybean field in eight major U.S. Corn Belt states, and these are the same eight growers who participated in the 2018 and 2019 versions of Crop Watch. Weekly updates will be issued for those fields through harvest.

The producers rate yield potential each week on a scale from 1 to 5. Scores of 1 or 5 represent yields close to or exceeding 15% below or above average, while 2 and 4 are assigned to yields around 5% to 10% from the average. Conditions are also evaluated from 1 to 5, where 1 is very poor and 5 is excellent.

The unweighted, eight-field average corn yield fell to 3.91 from 4.19 a week earlier on a large cut in Iowa and a minor drop in Nebraska. Soybean yield fell to 3.88 from 4.0 as a slight increase in Minnesota was offset by declines in Iowa, North Dakota and Nebraska.

Corn conditions are down to 3.66 from 4.25 on a huge reduction in Iowa and smaller cuts to North Dakota and Nebraska. Soybean condition fell to 4.0 from 4.09 on minor adjustments in North Dakota and Nebraska.


Conditions for the Iowa corn field fell to 1 from 4.5 a week earlier after last Monday’s derecho snapped many of the plants and flattened large parts of the field. Yield expectations are reduced to 2.5 from 4.5, although there will be much uncertainty around that score until harvest.

The storm brought wind gusts of more than 100 miles per hour (160 kph), and the producer notes that 85% of all his corn fields are as bad or worse than the Crop Watch field. He had four grain bins damaged, although they are still usable.

Soybean condition stays at 5 but yield falls a half point to 4.5 due to dryness. The derecho did not damage the soybeans, but the fast-moving storm dropped only 0.5 inch (13 mm) of rain on the crops, which were already in desperate need of rain.

Harvest should begin in about a month for the Iowa fields, although the producer expects corn to take at least three to four times longer than usual because of the storm damage.


Last Monday’s storm moved over the Nebraska crops earlier in the day, although the parched crops picked up only 0.2 inch of rain due to the speed of the system. All four ratings are lowered by a quarter point to 3.5 after another week with nearly no rain. The last decent rain was in the first days of July.

The North Dakota crops are in serious need of precipitation as well, and corn condition was cut to 2.5 from 3.5 as a result. Corn yield is unchanged at 3, although the producer notes downside potential, and both soybean scores are down a half point to 2 because of the dryness. Not all the surrounding area is dry, though, as some places not too far away are dealing with too much rain.

All four scores in Kansas hold at 4, but the past two weeks have been very dry with only 0.6 inch of rain. Corn and soybeans have been able to hang on thus far since there were not a lot of prolonged heat spells this summer and the crops got excellent rains earlier in the season.

The Minnesota producer raised soybean yield a quarter point to 5 as recent weather has been largely ideal. Pods are plentiful and are filling nicely. Corn and soybean conditions both remain at 5, and corn yield continues at 4.5.


Scores were unchanged in Ohio this week: 3.75 for both conditions, 4 for corn yield and 3.5 for soybean yield. Crops are holding together despite another week of minimal rain, but moisture is very much needed. The cooler temperatures are helping and those are expected to continue through the week.

The Indiana producer left all scores unchanged: corn condition 4.5, corn yield 4.75, soybean condition 3.75, soybean yield 3.5. The area got a half inch of rain last week, and there is some concern for soybean potential given the recent dryness.

All scores remain at 5 in Illinois. The crops received around 1 inch of rain last week, and harvest is expected to start in about five weeks.

The following are the states and counties of the Crop Watch corn and soybean fields: Griggs, North Dakota; Freeborn, Minnesota; Burt, Nebraska; Rice, Kansas; Cedar, Iowa; Crawford, Illinois; Boone, Indiana; Fairfield, Ohio.

Photos of the 16 Crop Watch fields can be tracked on Twitter using the hashtag #CropWatch20.

The opinions expressed here are those of the author, a market analyst for Reuters.

Reporting by Karen Braun; Editing by Peter Cooney