46 HORTICULTURAL SOCIETY OF NEW YORK. 



this year, in the seventh generation from the parent plant, the wilt resistance 

 is as marked as when first observed. If the other strains now being de- 

 veloped prove as lasting as this one their value will be very great. There 

 seems to be no reason why we should not find them so. 

 4. H'ilt Resistant Upland Selections. 



So far our experiments have dealt with Sea Island cotton. The wilt 

 disease is, however, even more destructive to the Upland varieties, Gossypium 

 hcrhaceum, and in 1900 an effort was made to find a resistant Upland cotton. 

 The first step was to plant on wilt infected land all the different varieties 

 obtainable, in order to compare their resistance, and provide a place where 

 selections could be made. The result of this experiment was to show that 

 Egyptian cotton, Gossypium Barbadense, was more resistant than our Upland 

 cotton. There was, on the whole, little difference in resistance between the 

 common Upland sorts, with the exception of Jackson's Limbless, which sur- 

 passed all the others, though it was by no means entirely resistant. Ex- 

 pressed numerically, on a scale of 1,000, the average coefficient of resistance 

 was 534 for the Egj'ptian varieties, 453 for Jackson and 98 for the other 

 Upland kinds. 



There were occasionally resistant plants in this field, and numerous se- 

 lections of such resistant individuals were made from it, but, unfortunately, 

 nearly all of them except the Jackson were destroyed the next year by pro- 

 longed wet weather. 



It was not fully demonstrated that resistant Upland strains could be pro- 

 duced by selection until this year (1902), when results were obtained that 

 were nearly as striking as those previously had with Sea Island cotton. These 

 experiments were carried on at Troy, Alabama, on land thoroughly infected 

 with wilt. The seed planted had been selected the previous fall from re- 

 sistant plants in badly diseased fields. Some non-resistant varieties were 

 planted beside them for comparison, and the results thus made more striking. 

 In a number of instances single rows planted with seed from selected plants 

 were almost free from disease, while the adjoining rows were badly attacked 

 or almost destroyed (PI. III.). The Jackson selections of the third gen- 

 eration were still resistant here, but a number of one-year selections were 

 equally as good. These strains will be carried on and tested more thoroughly, 

 after which the best of them will be distributed to the farmers for general 

 cultivation. 



The Cowpea Wilt. 



This disease is caused by the fungus Neocosiiiospora vasinfecta var. 

 tracheiphila Erw. Sm., and is similar to the cotton wilt in nature, but is 

 not of such great economic importance. The cowpea (Vigna sinensis) is, 

 however, the most valuable leguminous forage, plant in the South, and any 

 factor like this disease which hinders or restricts its use in crop rotations as 

 a soil renovator must be considered serious. It is mentioned here merely to 

 call attention to another striking instance of varietal resistance to disease. In 

 this case the resistant form was not developed by selection, as were the wilt 

 resistant cottons previously described, but was found already in cultivation, 

 though its disease resistant qualities had not been specifically pointed out. 



This cowpea, known as the Iron, has been tested in the experiments of 



