92 Maine Agricultural Experiment Station. 1920. 



reached in 1916 that the fundamental cause of this trouble was 

 lack of potash in the fertilizer.* 



These experiences led Maine potato growers to demand 

 that the manufacturers supply them with fertilizers containing 

 potash. The manufacturers met this demand as far as possible, 

 using various American sources of this material, but it was not 

 till 1919 that relatively large amounts of such fertilizers were 

 sold which contained potash in amounts at all comparable to 

 that used before the war. The so-called Searles Lake deposits 

 in California being the largest and most promising source of 

 American potash were naturally used in many cases. These de- 

 posits are not pure potash salts but contain mixtures of other 

 materials, including compounds of boron. Certain samples 

 of this potash, used in the manufacture of fertilizer that came to 

 the attention of the Station in 1919 contained the equivalent of 

 from 5 to 10 per cent of sodium biborate or borax. 



No attempt will be made to discuss in this publication the 

 general problem of the effect of boron or its compound borax 

 upon plant growth or to review previous literature upon this 

 subject. It may be said, however, that it is only within a very 

 short time that it has even been suspected that the small amounts 

 of borax that have been found in the fertilizers under considera- 

 tion would prove so toxic to farm crops as now appears to be 

 the case. 



Neither is an attempt made to discourage the use of Amer- 

 ican potash, provided it can be produced cheaply enough. so that 

 American farmers can afford to use it and provided it can be 

 sufficiently freed from deleterious impurities so that it can be 

 used with safety. The experiences of the past few years sim- 

 ply serve to emphasize the importance and even the necessity 

 for all concerned to unite in supporting, in every way possible, 



*For some reason, possibly due to more general use of stable ma- 

 nure, this trouble did not attract much attention in southern New Eng- 

 land till later. In 1918 it was sufficiently common in southern Connecti- 

 cut and on Long Island and surrounding territory 'to cause much com- 

 ment and alarm. Here again there was a strong tendency to look upon 

 it as a parasitic disease with Phoma as the causal fungus. On the other 

 hand Dr. Geo. P. Clinton, after a thorough canvass of the situation 

 seems to have reached, in part, similar conclusions as to the fundamental 

 cause, as were obtained in Maine. (See Potato Magazine Vol. 1, No. 

 12, June, 1919. Prematuring and Wilting of Potatoes, G. P. Clinton.) 



