Ag Weather Forum

Heat Affects Crop Ratings

Mike Palmerino
By  Mike Palmerino , DTN Senior Ag Meteorologist
U.S. corn crop ratings are still high at 72% good to excellent, but are now lower than hallmark recent years of 2016 and 2014. (DTN ProphetX graphic)

Crop ratings for corn and soybeans were mostly unchanged in the highest-production states last week; however, dryness and heat have begun affecting both southwest and northeast Corn Belt states.

Good-to-excellent ratings for corn in the highest-producing states of the Midwest were down by four points in Indiana, likely due to dryness; and by two points in Minnesota, likely due to wetness. Corn ratings in the rest of the top-producing states were basically unchanged. But, some notable declines because of consistent dryness and heat were in Kansas, with a four-point decline to under 50% good to excellent; Michigan, dropping 11 percentage points; and Missouri, with a 15-percentage-point decrease in the good-to-excellent total, now standing at just 33% good to excellent, the lowest such total since the 2012 heat and drought year. Nationally, corn crop ratings, which were sporting the same level of performance as 2016 and 2014, have now slipped below both those year. Ratings are still high historically, however.

For soybeans, the top-producing states were basically unchanged, except for a two-percentage point decline in Indiana's good to excellent total. But, once again, the northeastern and southwestern Midwest states had notably-lower numbers: Kansas with a six-point decline; Missouri, down eight percentage points; and Michigan, down ten percentage points in the good-to-excellent total.

Upper-atmosphere high pressure ridging edged out of the Southern Plains during the past week and into the Midwest. This brought on dry and hot conditions. The hotter temperatures have also led to corn pollination running well ahead of normal; corn silking this week is tabbed at 63% compared with 37% average. With this kind of pace, concern for early freeze damage this fall is very low. However, there could be an adverse effect on corn yield, due to lighter weight being put into the grain as plants consume more energy for maintenance. The forecast over the next ten days is for below-normal temperatures, which will be more beneficial for crops in this regard.

Soil moisture was depleted in the eastern Midwest last week, but not enough to be overly concerned about, as enough rain is expected to occur this week to help recharge soil moisture and temperatures will be moderate. Soil moisture is more varied in the western Midwest, with northern areas still having adequate to surplus soil moisture, and southern areas of the western Midwest now in severe to extreme drought, according to the U.S. Drought Monitor.

In the Southern Plains, row-crop stress has some easing in Kansas due to a better chance for showers in the next week. However, areas farther south are still likely to have above-normal temperatures and below-normal rainfall.

Mike Palmerino can be reached at



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