DISEASES OF TREES AND SHRUBS. 71 



ence of large, brown, dead patches 1 cm. or more in diameter, which 

 are more or less irregular and either central or marginal. The center 

 of the spots is frequently gray, and sometimes an evident zonation 

 is exhibited, due to the concentric arrangement of the dark conidial 

 tufts. 



Conidiophores amphigenous, densely fasciculate, many septate, dark 

 broAvn, GO to 75 b}^ G ^u; spores slender clavate, tapering gradually to 

 the end, few to many septate, hyaline, 70 to 187 by 2.8 to 3 /x. (PI. I, 

 fig. 7.) 



This blight causes the death of many leaves and much defoliation. 



Specimens collected: Austin, 463, 1910; Kerrville, 1603 (type specimen). 



Powdery mildew {Microsphaera alni (Wallr.) Wint.). — The lilac 

 is only rarely used in this region as an ornamental shrub, and so the 

 mildew is not common. 



Specimen collected : Austin, 1308. 



LIPPIA. 



Leaf -spot {Cylindrosporium lippiae Heald and Wolf, 32). — This 

 fungus produces on lippia {Lippia ligustrina (Lag.) Britton) three 

 to four circular spots 2 or 3 mm. in diameter to each leaf. The spots 

 have gray centers with narrow brown borders edged with a tinge of 

 yellow, and show in the center numerous white conidial tufts. 



Acervuli amphigenous, 30 to 100 fi in diameter, more on the upper 

 surface; spores hyaline, straight or generally curved, continuous or 

 one to three septate, 24 to 54 by 3 jn, nearly cylindrical. (PI. VI, 

 fig. 5). 



Specimen collected: Llano, 1756 (type specimen). 



MAGNOLIA. 



Leaf -spot {C oniothyrium, olivaceum Bon. var. grandiforae Sacc). — 

 This fungus on the magnolia {Magnolia grandiflora L.) occurs on 

 circular or subcircular, definite-margined spots, 1 to 5 mm. in diame- 

 ter, which are yellowish brown above with a narrow limiting zone 

 of darker brown and uniformly browni on the under surface, but of 

 a darker shade. There may be from a few to a dozen or more spots 

 to each leaf, but the fungus is not responsible for any defoliation. 



The pycnidia are on the lower surface and are uniform in color 

 with the spot, and consequently are not visible to the naked eye. 

 They are globular, 100 /x in diameter, which is much less than the 

 recorded size (300 to 350 /x), but the spores are of similar dimensions. 



Specimen collected : Georgetown, 2374. 



MAPLE. 



Leaf tip-blight {Gloeosporium sp. ?). — The maple {Acer sacchari- 

 num L.) is not indigenous to this section, and occurs only rarely 



226 



