90 A PLANT-DISEASE SURVEY IN TEXAS. 



DISEASES OF WILD PLANTS. 

 ARROW LEAF. 



Leaf-spot {Cercospora sagittariae Ell. and Kellerm.). — This disease 

 on the arrow leaf {Sagittaria sp.) is characterized by the presence of 

 grayish -brown, circular, or subcircular spots, 2 to 10 mm. in diameter, 

 with a darker border and exhibiting more or less concentric zonation. 

 In some cases adjacent foci become confluent, thus invohdng larger 

 areas of the leaf. Some chlorosis is frequent in badly affected leaves. 



Conidiophores on both surfaces, in clusters of 2 to 5, brown, straight, 

 continuous or one septate, 6 by 60 jn; spores straight or curved, taper- 

 ing, club shaped, four to five septate, contents homogeneous or dis- 

 tinctly two guttulate, hyaline, or faintly smoky, 120 to 140 by 5.5 

 to 8 ii. (PL IV, fig. 1.) 



Our specimens differ from C. sagittariae Ell. and Kellerm. in the 

 size of the spores, which are recorded as 60 to 80 by 3 to 4 /* (15). 



Specimens of Sagittaria land folia L. are affected with the same 

 Cercospora, which is not perfectly developed, since the spores are 

 50 to 80 hj 3.5 to 5 /x, indistinctly septate, more nearly straight, and 

 hyaline. The general s3'mptomatology is similar. 



Specimens collected: (1) On Sagittaria lancifolia L. — Collins's Gardens, San 

 Antonio, 1386 (represents young infectious with immature spores). (2) On 

 S. platyphijlla (Engelman) Sm. — New Braunfels, 1676; San Antonio, 3164; 

 San Marcos, 2121 (shows mostly immature spores and imperfectly developed 

 spots). (3) On Sagittaria sp.? — Lockhart, 20(54 (has but few mature spots). 



BLUEBONNET. 



Powdery mildew {Erysiphe polygoni DC). — The stem, leaves, and 

 pods of the bluebonnet {Lupimis texensis Hook.) are covered by the 

 powdery white network of fungous filaments. Affected plants are 

 paler green, with yellow-margined leaves, some of which are dry. 



Specimen collected : Austin, 3126. 



BLUET. 



Rust {Aecidium olderdandianum Ell. and Tracy). — The affected 

 leaves of the bluet {Houstonia angustijolia Michx.) show consider- 

 able chlorosis. Nearly all leaves are attacked, so that affected plants 

 are rendered conspicuous by their yellow color. The yellowish clus- 

 ter cups containing the orange-colored seciospores open to the lower 

 surface of the leaves. 



Specimens collected: Austin, 2947, 2951. 



BOERHAVIA. 



White-rust {Albugo platensis (Speg.) Swingle). — Blisterlike ele- 

 vations, each of which contains a white, powdery mass of spores, are 



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