Corn, soybeans and wheat are moving lower this morning. Corn is at 11-month lows, failing to hold base of support and risks further break. Wheat also struggling to hold contract lows. 

Rain overnight in Iowa was welcome. Farmer rating in Feedback from the Field there was lower than USDA.

Big speculators are selling ag. 

Federal Reserve meets in Jackson Hole, Wyoming, beginning Thursday. European Central bank will be there, too.