82 Walter H. Burkholder 



The roguing of parts of fields, and the use of seed from such parts for 

 planting in the following year, has been practiced with success with Perry 

 Marrow. It should be remembered, however, that this procedure can 

 be carried out with greater ease in some seasons than in others. In a 

 season favorable to the blight, when the diseases spread rapidly, some 

 difficulty might be encountered. Ordinarily, however, the method should 

 be beneficial. It should be emphasized that it is only among the varieties 

 that show some resistance that roguing should be applied. This method 

 of control with Red Kidney or an equally susceptible variety probably 

 would be of little avail. The diseases, especially the halo blight, spread 

 so rapidly through a field of Red Kidney beans that it would be impos- 

 sible to remove all diseased plants and have any plants left. 



The use of seed from disease-free fields is being practiced in New York 

 by many of the better growers. A field in which there are no diseased 

 seedlings to act as a source of infection remains reasonably free from the 

 bacterial blights, since infection from outside comes in late and has no 

 opportunity to do much damage. When it is impossible to find disease- 

 free fields, the use of seed from fields which show only a small percentage 

 of infected plants probably is more desirable than the use of seed from 

 fields where the percentage of diseased individuals is high. Nevertheless, 

 a very small percentage of blight in one year in a field of Red Kidney 

 beans may develop to 100 per cent in the second year. This may be 

 the case also with other extremely susceptible varieties. 



It has been found, recently, that Red Kidney beans grown in California 

 are entirely free from the bacterial blights, and that such seed brought 

 to New York has produced healthy fields the first year. Ultimately, 

 under our conditions the seed becomes contaminated. The length of 

 time for this to happen would depend, no doubt, on the care taken of 

 the seed. If planted next to or near a field of New- York-grown seed, 

 it probably would become infected very quickly. If isolated in a field 

 from all other beans, it would be safe for use as seed so long as no disease 

 appeared in the field. 



The demand for California-grown Red Kidney seed in New York has 

 become very great, and there is on the market considerable seed labeled 

 as being from California which probably never came from there. At least 

 much of the seed is infected with bacterial pathogenes. The bean-growing 

 areas of California are not known to the writer, and it is possible that 

 certain sections do not produce blight-free seed. The location and study 

 of areas able to produce disease-free seed would be of great benefit to the 

 bean industry. 



Spraying or dusting field beans for the bacterial blights, or even for 

 the fungous diseases, is not to be recommended under New York field 

 conditions. There are several reasons for this. The selection and care 

 of disease-free seed and the use of disease-resistant varieties are simple 



