DISEASES OF TEEES AND SHRUBS. 81 



WALNUT. 



Leaf -spot (Phleospora multimacidans Heald and Wolf, 32). — The 

 spots on the leaves of the walnut {Juglans sp.) produced by this fun- 

 gus average about 1 mm. in diameter, are subcircular, dark brown 

 with a darker border on the upper surface, and about a uniform 

 brown on the under surface. The spots may be few in number, or 

 they may be so numerous as almost completely to cover the leaf. It 

 is very severe in some cases and causes much defoliation. 



The pycnidia are hypophyllous, 30 by 45 fi ; the spores are generally 

 curved, hyaline, nearly cylindrical, 20 to 40 by 3 to 3.5 ^, and one to 

 three septate. (PI. V, fig. 11.) The general symptomatology and 

 the close relationship of the hosts indicate that this is the same species 

 as described on the sycamore (p. 79), although there are slight mor- 

 phological differences. 



Specimens collected: (1) On Juglans nigra L. — Austin, 1538, 2426; Victoria, 

 2337; Stockdale, 2621; Gonzales, 2682; Flatonia, 2721 (type specimen); Fal- 

 furrias, 2460. (2) On Juglans regia L.— Austin, 366; Falfurrias, 2461. 



WILD CHINA TREE. 



Leaf -spot (Cylindrosporium griseum, Heald and Wolf, 32). — Very 

 numerous grayish or whitish, circular or slightly angular spots are 

 produced on both surfaces of the leaflets and the rachis of the wild 

 China tree (Sapindus drummondii Hook, and Arn.) The spots vary 

 in size from 1 to 5 mm. with a predominating size of 1 to 2 mm. and 

 show more prominent veins owing to the shrinking of the tissue. 

 Thev may become confluent and cause extended dead areas (PI. XIX, 



fig. I). 



The acervuli are amphigenous, more abundant on the upper sur- 

 face, and are located immediately over the prominent veins (PI. VI, 

 fig. 12) ; they may be nearly circular in outline or much elongated 

 along the veins, pale when young, becoming darker with age. The 

 spores are cylindrical, slightly curved or sometimes straight, hyaline, 

 90 to 135 by 3 to 4.5 /*, and seven to nine septate (PI. VI, fig. 11). 



Specimens collected: Kerrville, 1588; Llano, 1757 (type specimen) ; Bastrop, 

 2026 ; San Marcos, 2098. 



Powdery mildew (Uncimda circinata Cke. and Pk.). — The my- 

 celium of the fungus forms a very effuse coating, most abundant on 

 the lower surface. The leaves first become yellow and later dry 

 and brown. The scattered perithecia are produced on the lower sur- 

 face, dark brown in color, 150 to 180 fi in diameter, with clear ap- 

 pendages about equal in length to the diameter of the perithecium. 

 The asci are elongated 65 to TO by 25 to 30 /x, containing six to eight 

 ascospores 15 to 18 by 9 to 12 fx. This species is somewhat doubt - 

 100833°— Bull. 226—12 6 



