bulletin is therefore prepared to supply this important information to 

 growers of tobacco in wilt-infested areas. It is particularly applicable 

 to the area included in the circle on the map (front page), where the 

 disease is generally prevalent although wilt is known, in addition, to be 

 present sparingly in the counties of Ashe, Guilford, Davidson, Yadkin, 

 Chatham, and Greene. 



EFFECTIVENESS OF CROPPING AND ROTATION TESTS. 



It is believed that the suggestion of definite systems of rotation can 

 best be made after results have been briefly presented showing the 

 value of the employment of rotation systems. The field on which all 

 these experiments were made was badly infested with tobacco wilt, since 

 about 75 per cent of the tobacco died the year before these experiments 

 were started. The data upon which these results are based were secured at 

 Creedmoor, N. C. The infested field in which the tests were made was 

 appropriately divided into plots of one-fourth acre, each of which was 

 cropped differently. The results of a five-year cropping system are 

 shown in Table I. 



Table I, Five-Year Cropping and Rotation Tests at 

 Creedmoor, N. C, in 1916. 



Name of Plot. Percentage of wilt. 



Rotation Plot A. (Corn, wheat, corn-clover and mixed grasses, 



clover and mixed grasses, tobacco) 10.9 



Plot B. (Sweet potatoes continuously) 21.2 



Plot C. (Peanuts continuously) 57.7 



Plot D. (Corn continuously) 3.7 



Plot E. (Red clover and mixed grasses continuously) 4.9 



Plot F. (Wheat and cowpeas continuously) 6.0 



Plot IB. (Tobacco continuously) 81.3 



It will be seen from this table that over 80 per cent of the plants 

 showed wilt where the land was cropped to tobacco each year. Most of 

 the M'ilt in rotation Plot A occurred in a poorly drained corner, and in 

 Plot B, only 5 per cent of wilt was present when the tobacco was 

 mature, whereas, when it was harvested, two weeks later, 21 per cent of 

 the plants were affected. Peanuts are subject to wilt, which accounts for 

 the large amount of disease on Plot C. In general, therefore, barring 

 Plot C, there Avas about 5 per cent of wilt on the several five-year test 

 plots as compared with 80 per cent on the one devoted to continuous 

 cropping with tobacco. Since it is important to learn the shortest prac- 

 ticable rotation for controlling tobacco wilt, a certain plot was planted 

 to crops other than tobacco for three years, another for four years, 

 another for five years, and another for six years. These results are 

 assembled in Table 11. 



