86 A PLANT-DISEASE SURVEY IN TEXAS. 



of yellow, shading out into the green tissue without a definite bound- 

 ary. On the lower surface the spots are more definite in outline, 

 with a brown center, surrounded by a yellowish-brown area with 

 often a zone of diffuse white bordering the spot. This zone is 1 to 2 

 mm. wide, and probably marks the advance of the fungus. Only 

 sterile fungous filaments were found. The affected leaves become 

 chlorotic. 



Specimen collected: New Braunfels, 1668. 



White-rust (Albugo platensis (Speg.) Swingle). — This species of 

 white-rust has been found on the common four-o'clock (Mirabilis 

 jalapa L.). Sori were very abundant on the leaves which turned 

 brown and shriveled, while those in which the disease was not so far 

 advanced showed a marked chlorosis. Wilson (51) does not record 

 this species for the four- o'clock, although it is common on other 

 species of the Allioniaeese. 



Specimens collected: Austin, 3019, 3101. 



GERANIUM. 



Bacterial leaf -spot. — Geraniums (Pelargonium sp.) have been found 

 to suffer in the greenhouse from what is apparently a bacterial spot. 

 The affected leaves show numerous subcircular, brown or somewhat 

 pellucid areas which are crowded full of bacteria. With the advance 

 of the disease the intervening leaf tissue turns brown, and extensive 

 dead, wrinkled areas result which" show the original foci as darker 

 spots scattered over the dead portions. Affected leaves generally 

 show more or less chlorosis and may fall before they turn brown. 

 (PI. XVII, fig. 1.) Young plants in the same house were affected 

 with a stem-rot which was probably also of bacterial origin. 



Specimens collected : Austin, 374, 474, 1920. 



HOLLYHOCK. 



Leaf -spot (Oercospora althaeina Sacc). — The numerous small circu- 

 lar or angular spots 1 to 5 mm. in diameter produced on the leaves 

 of the hollyhock (Althaea rosea (L.) Cav.) by this fungus are reddish 

 brown with a darker border and often a lighter center. The entire 

 area is raised on the upper surface and depressed on the lower. 



Specimen collected: Austin, 1904. 



IRIS. 



Leaf -blight (Heterosporium gracile (Wallr.) Sacc). — This blight 

 on the iris (Iris sp.) produces an abundance of spots which make their 



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