10 THE RED SPIDER ON COTTONo 



REMEDIAL MEASURES. 

 PREVENTION. 



Control on 'violets. — First among preventive measures against the 

 red spider is that of its control on violets. In most cases, as before 

 stated, infested cotton fields upon examination are found to have 

 near them infested violet borders. In early June of the past season, 

 in one particular instance, violets adjoining fields of past severe 

 annual infestation were thoroughl}^ sprayed. It is of great interest 

 to record that subsequent infestation in these fields was practically 

 negligible. These and similar observations certainly emphasize the 

 important part.that the violet plays in the seasonal history of the red 

 spider. 



Clean culture. — Borders of weeds and underbrush about fields 

 should be burned or grubbed out. Margining a field close to a spot 

 which was heavily infested the previous season there was found to 

 occur a thick border of wild geranium, dock, and other weeds which 

 at that time contained many red spiders. These weeds were de- 

 stroyed by burning over them a heavy application of straw. No 

 spiders appeared in the adjoining cotton throughout the season. 



Broadcasted cotton. — An opportunity was accidentally provided of 

 testing the value of thickly broadcasting cotton at the boundary of 

 a field as a trap crop for red spiders. This cotton, intended as a 

 cover crop, intervened between the cotton field proper and a large, 

 heavily infested border of violets — a former abundant source of 

 migration. The broadcasted cotton became infested and was later 

 plowed in. The adjoining field remained free from mites. The suc- 

 cess of this experiment would strongl}' indicate that the cotton trap 

 crop is one of the most practical cultural expedients to be used in 

 controlling this pest. 



Spacing. — Experiments at Batesburg, S. C, have shown that the 

 red spider commonly travels between plants upon the ground. This 

 shows the futility of spacing as a remedial measure. 



Time of planting. — The advantages of early or of late planting 

 are not sufficiently clear to justify serious consideration. It would 

 seem reasonable, however, to suj^pose that early planting would en- 

 able the plants to attain greater size and vigor b}^ the time of the 

 appearance of the spiders and that this would perhaps assist the 

 plants in withstanding the weakening effects of the pest. 



Rotation. — In an effort to test the rotational value of other crops, 

 cowpeas, corn, beets, and peanuts were planted in or near infested 

 areas. In addition, grains, beans, peas, onions, tomatoes, squash, 

 watermelon, okra, turnip, lettuce, and other vegetables in infested 

 locations have been observed frequently. Excepting the grains and 

 peanuts, the red spider has been seen commonly upon all of these. 



