The Effect of Borax in Fertilizers. 91 



potash was high in price and was for the most part unobtain- 

 able, a large amount of no-potash fertilizers were used for the 

 first time in 1916. Most frequently these contained 5 per cent 

 of ammonia and 10 per cent of available phosphoric acid and 

 were known as 5-10-0 goods. 



A "new potato disease" made its appearance in July of that 

 season. The foliage of the affected plants, instead of being a 

 normal, healthy dark green, showed first a peculiar bronzing 

 and yellowing. As the disease progressed the plants had, on 

 casual inspection, much the appearance of potatoes just previ- 

 ous to ripening. In the final stages the leaflets hung limp and 

 the entire plant wilted. Usually discolored areas appeared on 

 various parts of the stems. A very characteristic feature of the 

 trouble was the formation of a dry, discolored, spongy area 

 which involved the whole stem just at the surface of the ground. 

 Following this discoloration of the basal portions of the stem 

 the tissues would dry out, the stem would become hollow at that 

 point and the plant would fall over. Cross sections of the stem 

 sometimes showed a discoloration of the water or food conduct- 

 ing vessels. 



When the trouble first appeared in 19 16 there was some 

 reason to suspect that it was of a parasitic nature. The various 

 lesions scattered over the stems were of a light brown or red- 

 dish brown color and later usually showed a lighter colored cen- 

 ter. A number of different fungi were found to be associated 

 with the lesions, but most frequently the lighter colored portion 

 would be studded over with the fruiting bodies of a fungus of 

 the genus Phoma. Repeated attempts to reproduce the disease 

 in healthy plants by inoculation with cultures of this and other 

 fungi isolated from spots on potato stems obtained from dif- 

 ferent parts of the State resulted in failure. This seemed to 

 disprove the theory of a parasitic cause of the disease. 



It was soon discovered that this so-called "new disease" oc- 

 curred only where the 5-10-0 fertilizers were used and there, in 

 destructive amounts, it was largely confined to the poorer types 

 of soil. Even small amounts of potash in commercial fertili- 

 zers or the application of relatively small amounts of stable 

 manure in addition to the 5-10-0 fertilizer would correct the 

 difficulty. Later experience fully confirmed the conclusions 



