DISEASES OF FRUIT TREES. 31 



Leaf -spot (Cercospora kaki Ell. and Ev.). — The spots caused by 

 this fungus (16) are yellowish brown below, with a very dark, almost 

 black border, angular, 2 to 5 mm. in diameter or occasionally larger, 

 the veins frequently marking the edge of the spot. On the upper 

 surface the spots are darker brown with definite dark border, the 

 center becoming grayish and showing numerous black conidial tufts. 

 The affected leaves become chlorotic and fall. 



The conidial tufts are epiphyllous, very abundant, almost black, 

 and are composed of a dense aggregate of dark-brown, septate hyphae, 

 which extend 30 to 15 (x above the leaf surface and produce an aggre- 

 gate having the appearance of a pseudoparenchyma for an equal dis- 

 tance below the leaf surface. Spores densely fasciculate, olivaceous, 

 nearly straight, 3 to 5 septate, slightly clavate, cells sometimes two 

 guttulate, 45 to 60 by 3 to 1 \x. (PI. VII, fig. 3.) 



Our specimens differ from the type in the size and character of the 

 conidiophores and the colored, definitely septate spores. 



The disease was very abundant in the localities where it was 

 observed. 



Specimens collected: On Diospyros kaki L. — Gonzales, 2651; Hallettsville, 

 2778. 



Leaf-spot and fruit-rot (Phyllosticta biformis Heald and Wolf, 

 32). — The Mexican persimmon is affected by a fungus which pro- 

 duces black pycnidia in clusters upon the upper surface of the leaves. 

 At first they are surrounded by the green tissue, but later a dark- 

 margined spot 2 to 5 mm. in diameter is formed which is grayish 

 with the black pycnidia distinctly visible. The pycnidia show on the 

 fruit as minute pustules or slightly sunken spots, but are not very 

 evident on account of the dark color of the fruit. 



The pycnidia on the leaves are globose, 150 \x in diameter, ostiolate, 

 and produce an abundance of hyaline, densely granular spores, 6 by 

 9 /a. (PL V, fig- 8.) The pycnidia on the fruit are much more flat- 

 tened, are covered by the very thick epidermal wall, and contain 

 spores similar to those on the leaf except that they are dilute brown 

 in color. (PI. V, fig. 9.) 



Specimens collected : On Diospyros texana Scheele — Llano, 1739 ; Austin, 1548, 

 2896 (type specimen). 



PLUM. 



Bacterial leaf -spot (Bacterium pruni Erw. Sm.). — This is very 

 probably the same organism which has been described in this report 

 as occurring on the peach. It produces on the plum (Prunus spp.) 

 irregular dark areas which sometimes show somewhat of a shot-hole 

 effect. This diseased tissue, however, is crowded with bacteria. 



Specimens collected : Uvalde, 1934 ; San Marcos, 2132. 

 226 



