DECORAH, Iowa (AP) – A surprisingly chilly April has had an adverse effect on crops in Iowa.     Officials say freezing temperatures last month has damaged crops throughout the state. The Waterloo-Cedar Falls Courier reports that horticulture and agronomy experts say up to 80 percent of the apple crop in eastern Iowa has been ruined.  Apple trees blossomed about a month early because of unseasonably warm temperatures in March. But temperatures dipped to the low 20s for several nights in early to mid-April, killing those blossoms. Thousands of acres of corn may need to be replanted in the northern part of the state and Gail Nonnecke, a horticulture professor at Iowa State University, estimates Iowa strawberry production will be reduced by 20 percent.