THE RED SPIDER ON" COTTON. 17 



This plan has been tested in several instances and has given complete 

 immunity the following season. Too much emphasis can not be 

 l^laced on the importance of destroying, so far as possible, all weed 

 growth — especially the pokeweed, which should be grubbed out by 

 the roots. 



Control on violets. — As before stated, most cases of infestation in 

 urban localities have their origin in borders of cultivated violets 

 growing in near-by house yards. In several instances violets adjoin- 

 ing fields of past severe annual infestation have been thoroughly 

 sprayed, with the result that no red spiders appeared subsequently 

 in these fields. The objection to this treatment is the failure on the 

 part of the average person to persevere with the spraying until the 

 pests have been entirely exterminated. The most satisfactory pro- 

 cedure in such cases consists in the removal and destruction of the 

 t>tFending violets. 



Varietal immunity in cotton. — From several tests conducted in 

 different fields with numerous standard varieties of cotton, and from 

 the information volunteered by farmers from many portions of 

 South Carolina, data have been accumulated which clearly indicate 

 that certain varieties are susceptible to red-spider infestation, while 

 others exhibit considerable immunity. Careful observations on a 

 considerable number of varieties grown for the purpose showed that 

 Dixie '' Wilt Proof," Toole, Peterkin, Broadwell, and Cook suffer 

 most (in the order named) from the attack of the pest, while Hite, 

 Russell, Summerour " Half and Half," and Cleveland showed the 

 greatest immunity of all the varieties investigated. 



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 strongly indicate that the cotton trap 

 crop is a practical cultural expedient to be used in controlling this 

 pest. 



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

 red spider commonly travels betAveen plants upon the ground. This 

 shows the futility of spacing as a remedial measure. 



Time of planting. — There is yet much doubt as to the relative ad- 

 vantages of early and late planting. Extremely early planting nat- 

 urally permits the plants to develop a maximum growth of weed 

 and fruit by the time of serious mite appearance. It is noticeable 

 that plants of considerable size are rarely killed by the pest, nor are 

 well-advanced bolls commonly shed from infestation. On the other 

 hand, several fields about Leesville, S. C, which were planted as 



