PREFATORY NOTE 



With the greater specialization along all lines of 

 industry the problems that confront such a specialist 

 as the author of this book are felt more keenly and 

 the necessary remedies are more fully appreciated. 

 So there has grown up in the last few decades in 

 this country a body of agricultural experts, the 

 truck growers, who have found, as they have con- 

 centrated their attention more and more inten- 

 sively upon a limited number of crops, that they 

 are paying a great tax in the shape of losses due 

 to diseases. Probably, in fact we know that very 

 often it certainly is the case, similar losses are 

 suffered by general farmers, but with their large 

 plantings and less intensive culture these losses are 

 not appreciated as they are by the truck grower. 

 Other factors, too, enter in. In general the truck 

 crops occupy land near cities or which from its 

 adaptability to special crops or from its accessibility 

 to markets is accordingly more valuable than ordinary 

 farm lands. Furthermore, the crops themselves 

 have a greater monetary worth than the staple 

 crops. Both these factors make the losses by plant 

 diseases much more keenly felt. With this recogni- 

 tion of the losses incurred has arisen a demand for 



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