TWENTY-FIRST ANNUAL YEAR BOOK— PART VIII 665 



WEATHER AND CROP REVIEW. 



All reference in this publication to the effect of weather on crops, is 

 the result of cooperation between the United States Weather Bureau and 

 the Iowa Weather and Crop Service. 



Winter set in early and severely, preceding the crop season of 1920. 

 For the three winter months the average precipitation was the least of 

 record, but that of the early winter fell mostly as snow, giving ample 

 protection to winter grains and grasses during the rigorous, record break- 

 ing temperatures of early December. Under the snow covering, the ground 

 froze very little, though cold weather was practically continuous till after 

 the middle of February. There were considerable periods without snow 

 covering in the south central and southeast districts and extending a few 

 counties northward along the Mississippi and Missouri Rivers. About 6 

 per cent of the winter wheat was winter killed, which is less than the 

 average. 



March was wet, warm and windy. The snow cover disappeared in the 

 northern portion about the middle of the second week, having been con- 

 tinuous there since November. By the end of the third week frost had 

 left the ground. Several wind storms seriously damaged farm buildings. 

 The ground was too wet for much field work. 



April was cold and wet with a snow storm in the southern third of the 

 State on the 3d-4th. It was too cold for plant growth and too wet for 

 field work. However, a larger oats acreage than last year was sown in 

 the larger producing counties of the west and northwest portions of the 

 State. In the wetter, later, southern districts, oats seeding was pro- 

 longed unusually till as late as the middle of May. The development of 

 fruit buds was beneficially delayed by the cold weather. 



The season continued cool till about May 20, when a warm spell set in 

 that brought vegetation forward rapidly. Field work progressed slowly, 

 particularly in the south central and southeast districts, where much 

 corn was yet to be planted at the close of May. The most advanced sec- 

 tion was the upper Raccoon River watershed where corn planting began 

 about May 4 and was finished before the close of the month. In Union 

 and portions of adjacent counties not more than one-third of the corn 

 had been planted up to June 1. Fruit bloomed generally about the middle 

 of May, with conditions favorable for pollination. Peaches in the southern 

 tier of counties showed more bloom than for the past seven years. Young 

 live stock suffered greatly from the cold, wet, cloudy spring. 



June was warmer and drier than usual in most sections of the State. 

 The week ending June 15, with a mean temperature of 80 degrees was 

 the warmest week of the entire season and the warmest June week since 

 June 3-9, 1911. The humidity, however, averaged 20 per cent lower than 

 during a similar hot period last year, with the result that diseases of 

 small grains were much less prevalent, though causing considerable dam- 

 age to spring wheat in the west central and northern counties. The fol- 

 lowing week averaged 15 degrees cooler and was very beneficial for small 

 grains, which were m or approaching the critical heading and blooming 



