CONTROL OF BOLL WEEVIL IN MISSISSIPPI DELTA. 19 



rows extending beyond the plat lines of the picked plat were shaken 

 each time for further protection. A buffer system was also instituted 

 between the two plats to reduce as far as possible the influence that 

 either plat might have on the other. This system consisted of drop- 

 ping four rows from each plat immediately adjoining the dividing 

 line when considering the plat production. As treated throughout 

 the season the plats consisted of 22 rows each, or an area of 1.44 

 acres. With the four-row buffer dropped from each plat, however, 

 the plats proper each consisted of 18 rows with an area of 1.18 acres. 

 The soil was of a rather heavy " buckshot" type. The drainage 

 was fair over most of the plats, but a low area which extended across 

 the center of both plats was rather poorly drained. The outer two 

 rows of the check plat immediately adjoining the roadside ditch were 

 also lower than the remainder of the plat, especially at the eastern 

 end. In an ordinary season this difference in drainage would have 

 made little difference in the plats, but the summer of 1916 was so 

 exceedingly wet that the slightest difference in drainage was greatly 

 accentuated. As a result a narrow strip across the middle of the 

 picked plat and a wider strip through the check, as well as a con- 

 siderable area in the southeast corner of the check plat, suffered 

 from an excess of water. This tended to throw the plats " off 

 balance," as a much greater area in the check was injured than in 

 the picked plat. This fact of course should be borne in mind in 

 considering the results secured. 



PICKINGS. 



The idea of this test was to start the pickings as soon as the weevils 

 became sufficiently abundant to make the operation worth while. 

 In order to determine this time, regular examinations were made at 

 different points throughout the plats, beginning with May 8. On 

 this date 2,100 plants were examined, and no weevils were found. 

 On May 13, one thousand plants yielded eight weevils, but on the 19th 

 the same number yielded four weevils. On May 24, twelve weevils 

 were found on 1,000 plants. These records were made in belts 

 extending along the plats parallel to the timber line. After this 

 time, however, separate records were secured for the two plats. 

 The observations were made at both ends and the middle of each 

 plat. In the examination of June 1 it was found that plat 1 averaged 

 one weevil to 55 plants, while plat 2 averaged one weevil to 33 

 plants. On June 5 both plats averaged one weevil to 75 plants. 

 From these observations it is seen that a fairly heavy infestation 

 was being developed rather gradually in this field, and it was not 

 until the middle of June that a considerable increase in the number 

 of weevils was noted. Consequently, the plat was first picked over 

 on June 16, at which time 129 weevils per acre were collected. This 



