12 The Bulletin. 



no spread in the field except through the soil. This is by the slow growth 

 of the fungus through it, or by any transfer by implements in cultiva- 

 ton or by other means. * 



Control. — Do not plant seed that have had a chance to become con- 

 taminated externally. Do not allow stock to run on infected land. Clean 

 all implements after using on an infected field. Guard against_ manure 

 contamination. If only a small area is involved it will be advisable to 

 remove and burn affected stalks. It would be well to fence off such an 

 area and handle is separately. Fertilizers have no influence directly on 

 the disease and good results in crop yield will result from the proper use 

 of them and of uncontaminated manure. Two varieties of upland cot- 

 ton, Dixie and Dillon, possess a marked resistance to the disease, and 

 may be grown in a proper rotation on infested land. The Dillon seems 

 better adapted to North Carolina conditions. It is an improved strain of 

 Jackson Limbless, with some but not all, of the objectionable features of 

 that type modified. It has produced one and a half bales to the acre 

 under good cultivation on land where other varieties were a total failure 

 because of wilt; and this quality of resistance makes it valuable on wilt 

 infested soils in spite of its being only an average cotton otherwise. Four 

 other varieties that show a considerable degree of wilt resistance and are 

 worthy of trial are Wood (similar to Hawkins), a strain of Covington- 

 Toole, Modella (a selection from Excelsior), and several strains of Cook. 

 Cotton should not be planted on infested land oftener than once in three 

 years. If cotton wilt alone is present, any crops other than cotton and 

 okra may be planted on the land. Frequently nematode root-knot occurs 

 also, in which case crops susceptible to it must be avoided. (See under 

 "Boot-Knot of Various Crops," in this Bulletin.) A suggested rota- 

 tion* under such circumstances includes winter oats or rye, followed by 

 Iron cowpeas thickly sown ; when these are off, the land is put in winter 

 grain again, which may be followed by corn with Iron cowpeas between 

 the rows; a resistant cotton may be planted the third year. 



COWPEA WILT. 



Distribution in North Carolina. — Keports have been received from 

 Cabarrus, Cumberland, Granville, Johnston, Mecklenburg, Moore. 

 Wake, and Wayne counties. 



Cowpea is the only crop affected. 



Symptoms — The leaves turn yellow and drop prematurely, begin- 

 ning with the oldest. Often the* stems are left bare except for a few 

 young leaves at the top. If the plants are in a succulent condition, 

 wilting of the leaves may be prominent. Very young plants may rot 

 or damp off near the base. Affected plants are scattered through a field 

 or occur in particular spots. On cutting across the stem a dark brown 

 discoloration of the wood tissue is prominent. Some of the roots are 

 black and dead. m . 



This disease may be confused with nematode injury or with Rhizoc- 

 tonia root rot. The presence of the galls, which must not be confused 

 with the bacterial nodules or tubercles, distinguishes the former; and 



•Suggested by W. A. Orton in Farmers' Bulletin No. 333. 



