8 RELATION OF DROUGHT TO WEEVIL RESISTANCE IN COTTON. 



Without a supply of moisture in the soil the same drought that 

 hinders the reproduction of the weevils will also stop the growth of 

 the plants, thus reducing the advantage that might be gained from 

 the dry weather. But if the land has been well prepared by deep 

 plowing and thorough cultivation so that it absorbs and retains 

 moisture, the plants continue to grow and set their crop through the 

 dry weather. The weevils do not prosper during drought because 

 the young larva? are killed when the infested buds fall off and lie 

 exposed on the hot, dry ground. The importance of thorough till- 

 age is especially great in the very compact impervious soils of the 

 " black-land prairies " that produce a large part of the Texas cot- 

 ton crop. Unless such soils are stirred by cultivation very little 

 water penetrates beyond the surface layers, and these are very soon 

 dried out. 



Under conditions of humidity other factors determine the success 

 or failure of the crop. \Tet and cloudy weather is likely to interfere 

 with the growth of the plants without checking the propagation of 

 the weevils. The more humid the climate the greater the necessity 

 for a rapid, uninterrupted development of the plants if a crop is to 

 be set before the weevils can prevent. 



TTith conditions continuously favorable the weevils can seldom 

 cause any complete loss of the crop, but if a period of unfavorable 

 weather interrupts the growth of the cotton after the first crop of 

 buds has been infested, enough weevils may be bred to infest all the 

 subsequent buds, so that no crop can be set. The luxuriant growth 

 of the plants may continue, each producing hundreds of flower buds, 

 but all pruned off by the weevils. A whole field of the overluxuri- 

 ant weevil-pruned cotton may not average more than two or three 

 bolls to the plant. 



The idea of avoiding weevil injuries by early planting needs to be 

 supplemented by a recognition of the importance of securing an 

 uninterrupted development of the plants. The chief object to be 

 attained is the early setting of the crop in as short a period as pos- 

 sible after the plants have begun to produce flower buds in which 

 the weevils can breed. This object should be taken into account in 

 the breeding and adaptation of varieties and in devising improved 

 methods of culture for weevil-infested regions. 



COMPLETE CESSATION OF WEEVIL INJURIES DURING DROUGHT. 



The condition of the cotton on the San Antonio Experiment Farm 

 in the middle of July, 1909, afforded an unusually striking illustra- 

 tion of the importance of dry weather as a factor of cotton produc- 

 tion in Texas. In spite of the fact that weevils appeared very 

 numerous in the same fields early in the season and infested nearly 

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