DISEASES OF OKNAMENTAL PLANTS. 89 



SWEET ALYSSUM. 



Dodder (Cuscuta sp. ?). — Sweet alyssum (Konia maritima (L.) 

 E. Br. ) infested with dodder was found in one locality. Not flowering. 

 Specimen collected: San Antonio, 1372. 



SWEET PEA. 



Dodder (Cuscuta indecora Choisy). — This parasite was present on 

 the sweet pea (Lathy rus odoratus L.) and also on several other kinds 

 of plants growing near. 



Specimen collected : San Antonio, 1375. 



VIOLET. 



Leaf -spot (Alternaria violae Gall, and Dorsett). — This disease 

 occurs on the leaves of the violet (Viola odor at a L.), commencing 

 with small yellowish spots. The spots are somewhat circular, 1 to 5 

 mm. in diameter, and become j^ellowish white at maturity. They fre- 

 quently spread so that large areas are involved. 



Specimens collected : San Antonio, 1383, 1662, 3180 ; Uvalde, 1964. 



Leaf -spot (Cercospora violae Sacc). — Numerous small pale spots are 

 formed on the leaves. They vary in size from 1 to 3 mm., and are 

 margined by a zone of brown. 



Specimens collected: Beeville, 1856; Austin, 1917; Locknart, 2131; Seguin, 

 2329 ; Victoria, 2334, 2523 ; Georgetown, 2372 ; Cuero, 2577 ; Flatonia, 2739 ; San 

 Antonio, 3178. 



ZINNIA. 



Leaf -spot (Cercospora atricincta Heald and Wolf, 32). — This dis- 

 ease on the leaves of the zinnia (Crassina elegans ( Jacq.) Kuntze) is 

 characterized by the presence of irregular, angular, gray spots with a 

 brown border. When the spots are abundant this border is narrow 

 and the spots are small, 1 to 2 mm. in diameter. When they are few 

 they may be 4 mm. in diameter, with a broad marginal zone of pur- 

 plish or dark brown. The conidiophores are found on both surfaces 

 in small groups, brown in color, septate, 45 to 70 by 3.5 to 4.5 /*. 



The conidia are dilute brown, many septate, clavate, 100 to 200 

 by 4 to 4.5 /*. (PI. I, fig. 4.) 



This is quite common in gardens. 



Specimens collected: San Antonio, 1381, 1660; Victoria, 2506 (type specimen). 

 226 



