DISEASES OF TREES AND SHRUBS. 63 



Rust (Ravenelia versatilis (Pk.) Diet.). — The affected leaflets of 

 cat's-claw (Acacia greggii A. Gray) have minute (scarcely large 

 enough to be noticeable) brown pustules surrounded by chlorotic 

 tissue. The leaflets become yellow and drop off. 



Specimen collected: Uvalde, 1957. 



CEDAR. 



Cedar rust (Gymnosporangium exiguum Kern). — This is a new 

 species of Gymnosporangium which has recently been described 

 from Texas (35). Previous to the formation of telia on the cedar 

 (Juniperus sabinoides Nees) the presence of the infected twigs can 

 be detected only by the brown or yellow cast of the scale leaves. 

 The minute chestnut-brown telia are formed in the month of March 

 or early in April, and protrude from between the scale leaves. (PL 

 XVIII, fig. 2.) The affected twigs are killed and are later cast 

 from the tree. The fungus is frequently present in sufficient quan- 

 tity to give the tree a marked scorched appearance after the telia 

 have matured and disappeared. 



Specimens collected: Austin, 754, 855. 



Cedar-apples (Gymnosporangium (?) globosum Farl.). — This spe- 

 cies of Gymnosporangium produces brown galls varying in size 

 from minute globular enlargements to somewhat nodose structures 

 an inch or more in diameter. The gall is similar to that produced 

 by G. juniperi-virginianae , but shows marked depressions between 

 the telial areolae. The telia are flattened rather than terete, and 

 show pointed truncate or notched apices. 



Our specimens were sent to Mr. F. D. Kern, Purdue University, 

 Lafayette, Ind., who referred them to G. globosum Farl. The speci- 

 mens show no indication of a perennial character, and in this re- 

 spect appear to be quite similar to G. juniperi-virginianae, but the 

 spores are similar to those of G. globosum. 



Specimens collected : Austin, 497, 666, 758, 854. 



Whitening' of the cedar (Cyanospora albicedrae Heald and Wolf). — 

 The mountain cedar is frequently attacked by a fungus (31) which 

 produces extended white patches upon the bark of trunk or branches 

 and upon the surface of branches or twigs which have apparently 

 been corroded by the action of the fungus. The white areas may 

 completely encircle the branches, or they may be confined to one side. 

 Darker oval nodules, 1 to 2 mm. long by about 1 mm. wide, con- 

 taining the perithecia, are scattered over the whitened areas. Each 

 nodule contains one or more perithecia, which open to the surface by 

 excentrically located ostioles. On the bark these nodules are flat- 



226 



