14 THE RICE WATER-WEEVIL. 



RESULTS OF DRAINING. 



Conclusive observations upon tests of draining conducted by the 

 writer or under his instructions during the season of 1911 are pre- 

 sented in the following statements. 



At Crowley, La., on June 9, a rice grower drained some parts of 

 his field of early planted Honduras rice in which fully one-fifth of the 

 plants, then at a height of 15 to lo inches, showed yellow blades. 

 The roots had been rather severely pruned, but enough remained 

 together with newly grown ones to permit draining with safety. 

 As many as six and seven larvae infested the roots of a stool. Reflood- 

 ing was effected June 1!>. after a period of drying which had lasted 

 nearly 10 days. Quite a noticeable difference existed between the 

 drained and undrained rice on July 21. The plants in the drained 

 areas had nearly all headed out uniformly, while most of the un- 

 drained rice was behind in growth, either not having headed or hav- 

 ing heads just formed and blooming. Regarding recovery, the ownei 

 said that the plants which grew in the fresh water after reflooding 

 soon lost their yellow color and took on a vigorous growth of healthy 

 green, but in the undrained parts with standing water the plants re- 

 covered much more slowly. At harvest time the owner estimated 

 his best yield on land that had been drained to check the weevil 

 larvae. 



In the field of another grower, however, results were not so suc- 

 cessful. These small young plants were not injured badly and 

 showed only incipient spots and streaks of weak yellow color. This 

 was a variety of Japan rice. The field was drained May 29 and re- 

 flooded June 8, giving a drying of 10 days. One week after reflood- 

 ing the plants had taken on a fresh green color, and the infestation of 

 the most injured, root- had been reduced to a minimum, as shown 

 by the nearly normal growth. Owing evidently to a second infesta- 

 tion, during which no draining was done, an irregular belated growth 

 was displayed at heading time. "Whether the outcome might have 

 been worse without any draining can only be surmised. 



Acting under a cooperative agreement, Mr. C. G. Haskell reported 

 some very important results of his examinations at Almyra, Ark. 

 On draining a field July 20 he found 25 larva? on the roots of 25 

 stools. On flooding the field July 28 he found only two larva 1 on the 

 same number of roots. The result was accomplished by eight days of 

 draining and drying. A stool usually produced five stalks or stems. 

 By calculating percentages of infestation according to the number of 

 stalks the draining must have reduced the proportion of larvae from 

 20 per cent to l.G per cent. 



Again, on draining a field July 25 Mr. Haskell found 50 larvae on 

 the roots of 25 stools, but on reflooding the field July 31 he found no 

 more than 9 larvae per 25 stools. The draining and dicing therefore 



