12 



Twenty races, including the more loroniinent ones in cultivation, were 

 planted in a field that was thoroughly infected with the wilt disease, 

 and their comparative resistance determined in August by counting 

 the number of plants remaining healthy, those partiallj'' diseased, 

 and those killed. 



None of the races tested were entirely resistant, but some showed 

 great promise in this regard. The greatest resistance was shown b}' 

 tlie Egyptian cottons, Mitafifi, Abbasi, and Jannovitch, which with- 

 stood the disease to a very marked extent. Very few plants Avere 

 killed outright, although nearl}^ all were considerablj^ reduced in size 

 and yield. The striking difference in resistance between these sorts 

 and an ordinary- upland cotton (King) is shown in PI. II, fig. 1. The 

 race figured here, the Jannovitch, was imported from Egj-pt hy the 

 Department through Messrs. Barbour Lathrop and D. G. Fairchild. It 

 is a long-staple cotton of fine quality, said to be the result of a cross 

 between the Egyptian and sea island cotton, and regarded as being 

 adapted to upland culture. It has been widely distributed during the 

 past year, and promises to be of great value. The other Egyptian 

 sorts, Mitafifi and Abbasi, which were introduced at the same time as 

 the Jannovitch, were also verj^ resistant. They differed from that sort 

 chiefl}^ in the yield and the color of the lint. The most productive 

 strain of Egyptian cotton grown on infected land w^as Mitafifi, No. 3992. 



Sea island cotton, although closely related to the Egyptian, suffered 

 very much. It was practically' no more resistant than the upland 

 cotton growing beside it. Nearly all the upland races proved very 

 susceptible to the disease, though there were minor variations wiiicli 

 must have been due to varietal differences. 



One race only, the Jackson (Limbless), showed a marked resist- 

 ance. In this respect it far surpassed all other upland cottons and 

 nearly equaled the Eg^qitian. (See PL II, fig. 2.) The yield of this 

 race on wilt-infected land was very good. Many plants were injured 

 by the disease, but many others were exceptionally vigorous and 

 there is no doubt that selection from these healthy plants would 

 greatly increase the percentage of resistance. The relative resist- 

 ance of these races in the experiment mentioned is shown in the 

 following table : 



Table showing varietal resistance of cottons to the wilt disease. 



[The figures denote the comparative resistance of the different races on a scale of one thou- 

 sand.] 



Jannovitch . _ . 565 



Mitafifi (average of 3 strains) 559 



Ahhasi _ 479 



Jackson . ^ 453 



Sea island 233 



Eldorado 227 



Texas Wood 162 



Doughty 148 



Hawkins Prolific 142 



Brady 127 



Cook's Long Staple 124 



Excelsior ... 104 



Drake . . 90 



Jones 88 



King . 83 



Peterkin 71 



Truitt ... . 71 



Russell 55 



