64 A PLANT-DISEASE SURVEY IN TEXAS. 



tened, while on the twigs from which the cortex has been corroded 

 they stand out more prominently, owing to the fact that the sur- 

 rounding wood tissue has been more corroded than the wood tissue 

 which constitutes the stromatic nodule. The stromatic nodules on 

 the decorticated twigs are also more nearly black, while those on the 

 bark are dark gray. 



This fungus is so constantly present on the mountain cedar that the 

 occurrence of white patches on the bark has been given as one of 

 the characteristics of this species of cedar (3). The fungus which 

 causes this trouble has been under investigation by the writers for 

 some time, and it seems probable that it represents a new and unde- 

 scribed species and genus. A more detailed consideration has been 

 published in Mycologia. 



A study of the affected cedars under field conditions indicate that 

 the fungus is a true parasite. Affected trees frequently show a large 

 quantity of dead decorticated twigs and branches. 



Specimens collected: Austin, 306, 1434, 2865. Coextensive with the distri- 

 bution of the mountain cedar. 



COTTONWOOD. 



Leaf -spot (Septoria musiva Pk.). — Numerous small, angular areas 

 are formed on the leaves of the cottonwood (Populus deltoides 

 Marsh), which are brown, but may become grayish. The pycnidia, 

 containing hyaline, curved spores 30 to 35 /x long, appear on the upper 

 surface. 



Specimens collected: Lockhart, 2076; San Marcos, 2117. 



Leaf -spot (Septoria populicola Pk.). — This species differs mainly 

 from the above in the fact that the pycnidia open on the lower sur- 

 face and the spores are 60 to 75 by 3 to 4 p. The amount of defolia- 

 tion is only slight. 



Specimens collected: Austin, 413, 1426, 1432, 2910; Victoria, 2339; Gonzales, 

 2656. 



Rust (Melampsora medusae Thm.). — Observed only in a single 

 locality, where it was causing no serious damage. 

 Specimens collected: Austin, 162, 414. 



CRAPE MYRTLE. 



Leaf-spot (Cercospora lythracearum Heald and Wolf, 32). — Circu- 

 lar to subcircular indefinite-margined areas appear on the foliage of 

 the crape myrtle (Lagerstroemia indica L.). These spots, varying in 

 size from 2 to 8 mm., are uniformly yellowish brown below and dark 

 brown above with a zone of limiting yellow tissue paling out into the 

 green tissue. 



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