58 A PLANT-DISEASE SURVEY IN TEXAS. 



are cylindrical, fusoid, 30 to 36 by 3 to 4 j*. This measurement of 

 width is in excess of the original description (2.5 /*). 



"Where the spotting is abundant the leaves become yellow and fall. 



Specimen collected: Gonzales, 2652. 



Leaf-spot (Septoria submaculata Wint.). — As a result of the attacks 

 of this fungus definitely margined spots 1 to 2 mm. in diameter are 

 formed. In the early stages they are circular and purple with a 

 whitish center ; later they become brown and angular, 3 to 4 mm. in 

 diameter and are limited by the veins of the leaf. 



On the upper surface are black pycnidia, embedded in the leaf 

 tissue. The spores are 20 to 30 by 1 to 2 /*, hyaline and cylindrical. 



Although the leaves were abundantly spotted, no defoliation was 

 seen. 



Specimen collected: Austin, 1546. 



BLACK HAW. 



Leaf -spot (Hendersonia foliorum Fckl. var. vihurni Sacc). — This 

 fungus produces angular spots, 2 to 5 mm. in diameter upon the 

 leaves of the black haw (Viburnum prunifoliuru L.) The pycnidia 

 are sparsely scattered over the upper surface of the spots which are 

 gray or dirty yellow with a darker border. The spots may be few 

 in number on each leaf, or as many as 15. 



Specimen collected : Austin, 331. 



BLACK LOCUST. 



Leaf -spot (Cylindrosporium solitarium Heald and TTolf, 32). — 

 This disease of black locust (Robinia pseudacacia L.) is character- 

 ized by the presence of minute brown spots upon the leaflets. In the 

 early stages of the disease the leaflets have their normal green color, 

 and the spots show as circular areas, 0.5 to 1 mm. in diameter, which 

 have a pale-brown center and a narrow, darker brown border, sur- 

 rounded by a faint zone of chlorotic tissue. As the disease progresses 

 the entire leaflet turns to a bright-yellow color with the exception 

 of narrow zones of pale green which persist around the circumfer- 

 ence of the brown spots. In this stage the spots show an outer zone 

 of green, a middle zone of dark brown, and a central area of light-" 

 brown or grayish tissue. (PL XIII, fig. 4.) Affected leaflets may 

 show from 1 to 40 spots, and these are generally isolated, although 

 they may be somewhat clustered. The leaflets fall soon after they 

 assume the yellow color and sometimes even before the complete 

 chlorotic stage has been reached. In many cases considerable de- 

 foliation results. 



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