42 A PLANT-DISEASE SURVEY IN TEXAS. 



Bacterial leaf-spot. — The leaves have small, elevated, brown spots 

 from 0.5 to 1 mm. in diameter. The leaf tissue between them is 

 more or less chlorotic. Each pustule is crowded full of bacteria. 

 No record has been found of a pepper disease due to these organisms. 



Specimen collected: Uvalde, 1950. 



Fruit-spot. — The sweet pepper is very commonly spoiled by the 

 formation of large, dry, brown, more or less sunken areas on the 

 side exposed to the sun. An Alternaria was found to be present, but 

 inoculations into healthy fruits failed to reproduce the spots. This 

 would suggest that the trouble is physiological and that the fungus 

 associated with it is merely a saprophyte. 



Specimens collected : Austin, 1536 ; San Antonio, 1783 ; New Braunfels, 1683. 



Leaf -spot (Cercospora capsiei Heald and "Wolf. 32). — Leaves in- 

 fested with this fungus form spots 1 to 7 mm. in diameter, mostly 

 circular or subcircular. The spots are raised on the upper surface, 

 brown at first, later becoming grayish brown. They are margined 

 by a very definite darker zone, outside of which is a more or less ex- 

 tended halo of yellow. Where- the spots are abundant, the leaves 

 become chlorotic, then wilt and fall. The conidiophores are borne 

 on both surfaces, brown, grouped in clusters of 10 to 15. 30 to 60 by 

 4.5 to 5.5 p., and are occasionally septate. The conidia are borne 

 on the tips, are dilutely brown, 75 to 125 by 4 to 5 /x, clavate, generally 

 straight, and several septate. (PL IV, fig. T.) 



Specimen collected: Cuero, 2592 (type specimen). 



POTATO. 



Early blight (Alternaria solani (Ell. and Martin) J. and G.). — 

 This was observed to be abundant on the potato (Solanum tuberosum 

 L.) in several localities, producing large, irregular, brown spots. 



Specimens collected : San Antonio, 1402, 3145 ; Kerrville, 1601 ; Austin, 3134. 



Rhizoctonia disease (Corticium vagum, B. and C. var. solani Burt) . — 

 The stems are cankered and have the characteristic pustules. The 

 tubers also are very frequently destroyed, especially in irrigated 

 gardens, during a rainy period. (PL X. fig. 2.) 



Specimen collected : San Antonio, 3147. 



Scab (Oospora scabies Thax.). — Observed in a single locality. 

 Specimen collected: San Antonio, 1402a. 



RADISH. 



Powdery mildew (Erysiphe polygoni DC). — The leaves of the 

 radish (Raphanus sativus L.) at first are covered with a powdery 

 coating, becoming chlorotic and at length entirely dry. 



Specimen collected: Cotulla, 2931. 

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