xiv Prefatory Note 



help in the prevention of the diseases responsible 

 for the damage. So plant pathologists have had to 

 direct their attention to diseases of truck crops. 

 The present book is an attempt by such a pathologist 

 who has specialized along this line to meet the de- 

 mand for help in the way of giving information as 

 to the diseases occurring on truck crops and, so far as 

 it is possible, telling how these losses may be pre- 

 vented or at least reduced. 



The last quarter century has seen a marvelous 

 development of that division of the science of Botany 

 that is devoted to the study of plant diseases, Plant 

 Pathology. As each crop has been given greater 

 attention the number of diseases ' found to occur 

 upon it has been amazing. Plants nearly related 

 to each other may have some of their diseases in 

 conamon, but even with very closely related species 

 some of the troubles affecting them wiU be different. 

 When we now consider the large nimaber of crop 

 plants that are the subject of intensive culture as 

 truck crops, and note, fiuthermore, that they re- 

 present the most diverse famiUes of plants,- it is not 

 to be "wondered at that the number of organisms 

 causing diseases of truck crops is a large one. The 

 author by igrouping the crop plants together by their 

 botanical affinities has taken fuU advantage of the 

 fact that nearly related plants may suffer from some 

 of the same diseases and thus has made it possible in 

 some cases to consider such diseases only once for 

 several different, but closely related, crops. 



Considerable attention is directed to the symptoms 



