316 EXPERIMENT STATION RECOED. [Vol. 37 



" The results obtained from using the factors 1/2 for 110 years and 2/3 for 

 50 years are conservative for eastern United States. These factors, however, 

 should not be used for the western part of the count it. for they are shown 

 to be much less west of the Mississippi River." 



Effect of a late spring upon crop yields (C7. S. Dept. Agr., Nat. WeaHier and 

 Crop Bui. 11 (1917), pp. 2, S, 5, figs. 4). — Diagrams are given which show the 

 fallacy of the belief that a late spring is usually followed by a poor crop season, 

 especially as applied to corn, oats, and cotton. 



Safe dates for planting com (U. S. Dept. Agr., Nat. Weather and Crop Bui. 

 8 (1917), pp. 2, S). — It is stated that the average date of beginning corn plant- 

 ing in the United States varies from February 1 in the extreme South to the 

 latter half of May in the extreme North. The average number of days neces- 

 sary for maturity of the crop varies from 120 days or slightly less in the North 

 to 150 days or slightly more in the Gulf States. In the corn-belt region the 

 growing period varies from about 130 days in Kansas to 140 days in the Ohio 

 Valley, the period varying, however, with the variety of corn, soil, prevailing 

 temperature, moisture, etc. 



" The average date of the first killing frost in the fall east of the Rocky 

 Mountain region varies from about the middle of September in extreme north- 

 ern districts to December 1 at some distance from the Gulf coast. From Ne- 

 braska and Iowa eastward to northern Ohio the first killing frost in the fall is 

 observed on the average between Octot)er 1 and 11. From Kansas and Mis- 

 souri eastward to the Appalachian Mountains the frost date varies between 

 October 11 and 21. In Oklahoma these dates are between October 21 and 

 November 11, while in central and eastern Texas they vary between November 

 11 and November 25. Eastward across the Southern States from Oklahoma 

 and Texas the variation from the dates recorded in those States is largely a 

 matter of topography. Between the Appalachian Mountains and the Atlantic 

 coast the dates vary from November 1 to 11 In the South ; October 21 and No- 

 vember 1 in central districts ; and October 11 to 21 farther north. In northern 

 New England and central New York State frost frequently occurs before the 

 middle of September." 



The number of days from June 1 to the average first killing frost in the fall 

 varies from 100 to 120 in the extreme North to 120 to 140 in the principal 

 corn-growing region, and from 150 to 170 in the Gulf States. 



The above figures show that there are few sections of the country east of 

 the one-hundredth meridian where corn may not safely be planted any time 

 during May, with the expectation that it will mature before the average fall 

 frost date. " In some sections of the central part of the country, and In many 

 districts in the South, corn may be planted until near the close of June, with 

 the expectation that it will mature sufficiently to escape damage from frost 

 nine years out of ten." 



Weather and cotton (U. S. Dept. Agr., Nat. Weather nnU Crop Bui. 9 (1917), 

 p. S). — From a review of the data bearing on this subject, it is concluded that 

 " In general, the most favorable weather conditions for cotton are warm and 

 comparatively dry weather during May and June and moderate rainfall during 

 the succeeding three months. The most unfavorable are cool and wet weather 

 during the former period and dry and hot during the latter. It is especially 

 harmful for May and June to be cool and wet, as this greatly retards growth 

 and final maturity, and also prevents proper cultivation. For best results 

 thorough cultivation is especially Important, owing to the length of the time 

 between the final chopping-out period and the maturity of the last fruit, and the 

 resulting tendency of the fields to become grassy. 



