PLAN OF THE WORK. 23 



203 to 324 and the cloudy days from 41 to 162 (6) in various parts 

 of the territory. 



Injury to truck crops and nursery stock was especially severe where 

 irrigation was practiced. Nematodes, which thrive best with an 

 abundant supply of moisture, caused the formation of galls and the 

 consequent improper functioning of the root system. While injury 

 from this source is very general over the territory, it is more pro- 

 nounced in irrigated fields. In similar places Rhizoctonia was 

 abundantly present on potatoes, tomatoes, okra, and eggplants. 



The excessive drought together with the high temperatures pro- 

 duces a languid condition in the aerial parts of the vegetation and 

 thus renders them more susceptible to the attacks of fungi. This 

 would account for the prevalence of leaf-inhabitating fungi, of which 

 the genus Cercospora is an abundant representative. While it is 

 not known that any correlation exists between the presence of this 

 genus and high temperatures, yet it seems more than a coincidence, 

 since Cercospora diseases are not nearly so abundant in the Northern 

 States even in arid places or during seasons of drought. 



PLAN OF THE WORK. 



The collections for this survey were begun in the fall of 1908. 

 These were entirely in the immediate vicinity of Austin, as were 

 those of a part of the following season. The greater part of the 

 work, of necessity, was performed in the months of July, August, 

 and September, 1909, with a less amount during the succeeding 

 months of that year. Then again, in the spring of 1910 a very con- 

 siderable proportion of time was given to the field work. 



Attention was given primarily to the diseases of cultivated plants, 

 with an attempt to cover all the varieties of field, truck, nurseiy, 

 and orchard crops. As much time as was possible was given to 

 the consideration of greenhouse and ornamental plants, with reason- 

 able emphasis upon shade and forest trees. The natural vegetation 

 could not be entirely left out of account, however, because of the 

 fact that the same organism may be the cause of diseased conditions 

 in both wild and cultivated forms. 



Notes on the symptomatology from field conditions were carefully 

 made in the field at the time of collection. The value of accurate 

 observations in the field in regard to the symptoms attending the 

 progress of the various diseases can not be overestimated. Actual 

 determinations of the causal organism would have been impossible 

 in manv instances without them. 



Many of the facts which must be incorporated in our future pathologies can 

 not be obtained from dry herbarium specimens, but must be recorded in the 

 field while the patients are still alive and not after they are dead and have been 

 stored away in herbarium sepulchres (30). 



