8 



THE CONTROL OF COTTON WILT AND ROOT-KNOT. 



WEEDS ATTACKED BY ROOT-KNOT AND THEREFORE TO BE ERADICATED. 



Balloon vine (Cardiospermum halicacabum 



L.). 

 Indian potato {Ipomoea sp.). 

 Maypop or passion flower. {Passifiora 



incarnata L.). 

 Mayweed (Anthemis cotula L.). 



Papa\'a or melon pawpaw (Carica papaya 



L.i 

 Pigweed (Amaranthus hybridus L.). 

 Purslane {Portulacca oleracea L.). 

 Sawbrier (Smilax glauca, Walt.). 

 Sweet fennel (Foeniciduni vulgare Hill). 



The following rotations are suggested for fields infected with both 

 wilt and root-knot: Beginning in the fall, sow winter oats if they can 

 be gotten in early enough to make a fairly good growth before it is 

 necessary to plow the land for the next crop. Plow the oats under 

 for green manure and plant corn %vith Iron or Brabham cowpeas 

 between the rows, putting the corn in at the usual time, about March 

 15 to 20 for middle Georgia and South Carohna. In the fall sow a 

 winter gra;in; this can be cut for ha}^ the next May or allowed to ripen. 

 Coupeas, either the Brabham or the Iron variety, may then be sown 

 broadcast, or, better, in 2-foot drills, where they can be cultivated once 

 or t^nce. Cut the cowpeas for hay and follow with another crop of 

 winter grain. This should be plowed under in the spring in time to 

 plant a wilt-resistant variety of cotton the third year. If it is desired 

 to make a 4-year instead of a 3-year rotation, the last-mentioned crop 

 of winter grain may be harvested for hay or allowed to ripen, a second 

 crop of Iron or Brabham cowpeas broadcasted for hay, and this fol- 

 lowed b}" oats to be plowed m for green manure. A wilt-resistant 

 variety of cotton should then be planted. "Wheat, rye, or barley may 

 be substituted for oats as a winter gram crop and velvet beans for the 

 Iron or Brabham cowpea in the more southern districts. 



THE CONTROL OF WILT BY THE USE OF RESISTANT VARIETIES. 



The experiments of the Bureau of Plant Industry, wliich have now 

 been carried on for 12 consecutive years, have shown that the only 

 practicable solution of the wilt problem is through the use of resistant 

 varieties developed by special breeding. Such varieties have been 

 produced and grown successfully for the past six years m a large num- 

 ber of localities ' until no doubt remains as to the possibility and 

 practicability of controlling wilt in this manner. During this time 

 these cottons have been further improved by selection for better 

 ^ield, greater resistance, higher percentage of lint, and other desirable 

 characters. 



The first wilt-resistant Upland cotton produced was the Dillon, a 

 limbless, cluster variety derived from the old Jackson Limbless. 

 The Dillon cotton is highly resistant to wilt and is a productive 

 variety. It has produced a bale and a half per acre where other 

 varieties were a complete failure. The yield of lint is from 37 to 38 per 

 cent. Tliis variety has been quite widely grown for several years with 

 uniform!}" good results. 



[Cir. 92] 



