* Rains could limit yield loss in corn
* Soy fields vibrant after showers
By Karl Plume
TRAER, Iowa, July 26 (Reuters) - Corn yield prospects in central and east-central Iowa were highly variable as drought and periods of extreme heat this summer diminished production potential, scouts on a crop tour said Thursday.
Plants were tall and mostly green, although leaves on some plants were turning brown as the worst U.S. Midwest drought in five decades expanded from harder hit states such as Illinois and Indiana, scouts on the MDA EarthSat July Crop Tour observed.
Some ears appear to have pollinated with little stress, which scouts said was likely aided by early planting. But kernels on others were sparse, not filling all the way to the end of the cob or not completely around, which was likely caused by heat and moisture stress at pollination.
Ears were also beginning to abort kernels at the tip due to a lack of moisture.
Fields surveyed in the No. 1 corn and soybean growing state of Iowa on Thursday morning received some rain -- enough to dampen soils but not enough to create puddles -- but more rain would help stop the yield loss, scouts said.
Johnson, Linn and Benton counties had, before Wednesday night's rain, received less than 50 percent of their normal rainfall since June 1.
Three fields surveyed in the counties averaged about 125 bushels per acre, down 27 percent from a yield of about 169 bpa last year.
Soy fields in Iowa got rain overnight, although totals were lighter than expected and plants needed more. Still, the soybean plants were vibrant after the rain and temperatures cooled into the low 80s degrees Fahrenheit (27 degrees Celsius). Flowers seem to have popped up overnight and soils in fields were wet but not muddy.
The tour stops in Fort Dodge, in the western part of the state, later on Thursday before concluding on Friday in Omaha, Nebraska.
(Reporting by Karl Plume; editing by Jim Marshall)