24 A PLANT-DISEASE SURVEY IN TEXAS. 



Within a few days after the collections Arere made a preliminary 

 diagnosis was made in the laboratory and the notes were completed, 

 accompanied by drawings and actual measurements when it was 

 deemed advisable. In working over the material at a later date it 

 was occasionally found necessary to change the previous determina- 

 tion. The time available permitted only a limited amount of culture 



work. 



It is not to be supposed that the list is by any means complete. 

 The territory, comprising over 30,000 square miles, is too large to be 

 covered in the time which has been devoted to the work. In view of 

 the diversity of crops grown in the various sections and the fact that 

 similar crops may reach the same stage of maturity over a very con- 

 siderable range at the same time, and that it has not been possible 

 to make the work continuous throughout an entire year, the incom- 

 pleteness will be properly emphasized. Enough, however, has been 

 done to be very suggestive and indicative of the profitableness of 



further work. 



DISEASES OF FRUIT TREES. 



APPLE. 



Black-rot {Sphaeropsis Tnalor'wn Pk.). — This is the most common 

 and serious disease of the apple {Mains sylvestns Miller) in this 

 section. The foliage of the young plants in the nurseries was 

 abundantly spotted and many twigs and limbs of the trees in orchards 

 were seriously affected or entirely dead. 



Specimens collected: Austin, 4G0, 1270, 1911; Kerrville, 1598; Boerue, 1651, 

 1652; Nursery, 2552; Stocl<dale, 2626; Gonzales, 2659, 2660. 



Crown-gall {Bacterium tumefaciens Erw. Sm. and Townsend). — 

 Trees about 8 years old were found seriously affected in one locality. 

 A chlorotic condition preceded the death of the tree in each case. 



Specimens observed : Llano, 1772. 



Leaf -spot {Cercospora mali Ell. and Ev.).— The spots caused by 

 this fungus are circular or subcircular, 2 to 5 mm. in diameter, silver 

 gray on the upper surface with a narrow broAvn border, Avhile 

 on the under surface they are of a uniform brown. Badly af- 

 fected leaves turn yellow and fall from the trees, or they may 

 show extended brown areas of dead tissue in which the gray spots 

 are quite conspicuous. The conidial tufts are very abundant and 

 conspicuous on the gray centers of the upper surface, showing as 

 minute black specks; they are inconspicuous on the brown ground of 

 the under surface, but are fairly abundant. It may be noted that 

 the original description characterizes the fungus as " epiphyllous " 

 (18), while a careful examination of our specimens reveals the fact 



226 



