DISEASES OF VEGETABLE AND GARDEN CROPS. 



By JOHX A. 8TEVEXS0X, Pathologist, Insular Experiment Station. 



Ju making inquiries among the agriculturists of the Island as to 

 why the growing of the common northern vegetables was not taken 

 up tor at least a home supply, the reply has universally been that 

 all such attempts ended in failure. At times with the weather favor- 

 ing one crop would be secured, but a second was apparently imposy- 

 sible. Wliile it was realized that tropical weather conditions would 

 not be conducive to the best growth of northern vegetables, still it 

 was difficult to see why such complete failures resulted. Consequently 

 a close watch was kept on the various trial plots at the Station and 

 in so far as possible upon gardens in other parts of the Island; in 

 particular the public gardens and those maintained in connected with 

 the normal school at Rio Piedras. 



As a result observations have been made upon a very large number 

 of fungi causing diseases of the various garden crops. In some cases 

 these have attacked with such virulence as to readily explain the 

 numerous failures reported, especially those with cucumbers and to- 

 matos. Practically all of the troubles so far observed are those of 

 common occurrence in continental America and have all doubtless 

 be(^n introduced with the seed or other plant parts. ^lany interesting 

 questions have arisen in the work with these diseases especially as 

 regards their dependence upon weather conditions (temperature and 

 humidity), their relation to insects as spore carriers, and above all 

 their modes of attack. Soil and cultural conditions have likewise 

 played an important part. Some of these points will be touched upon 

 in the separate account of the diseases to follow, but othei*s must be 

 deferred until more detailed investigations can be carried out. 



Some previous work has been done on the diseases of vegetables 

 in Porto Rico, but with the exception of short notes of occurrence 

 in reports of the Mayagiiez Experiment Station, there are no pub- 

 lished records. In Bulletin 7 of that Station, issued in 1906, refer- 

 ence is made, in connection with cultural directions for the various 

 vegetal)les, to certain of the more common diseases and some sug- 

 gestions for control are made. Certain ones are definitely reported 

 as found in Porto Rico, but for the most part it is impossible to tell 

 whether a given disca.se is so reported or whether tlie note is merely 



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