DISEASES OF ORNAMENTAL PLANTS. 83 



can be noted by the presence of purplish areas 1 to 2 mm. in diameter. 

 These spots become depressed, often show concentric zonation, and 

 increase in size to 4 to 8 mm., with a wide area of yellow, dead tissue 

 around them. The yellow areas may fuse, thus involving a large part 

 of the leaf, so that it is completely destroyed. (PL XVII, fig. 2.) 

 This is probably the same disease that occurs in France, although it 

 was not observed to attack the stems but only the leaves (40). The 

 disease was observed in only a single locality, on greenhouse plants. 

 No cultural work with the organism was attempted. 



Specimens collected : San Antonio, 1411, 3176. 



CANDYTUFT. 



Dodder (Guscuta indecora Choisy). — This parasite was observed 

 on the candytuft (Iberis sp.) in only a single locality where it had 

 spread to a considerable extent. 



Specimen collected: San Antonio, 1372. 



CANNA. 



Leaf -blight. — A very serious leaf disease of the canna (Canna 

 indica L.) appears at first as minute yellowish spots which become 

 from 5 to 10 mm. in diameter, with brown centers. When isolated 

 they are subcircular in outline, but when abundant they coalesce so 

 that large irregular areas are involved. The brown parts show 

 alternating concentric rings of lighter and darker areas of brown. 

 Examination reveals no evidence of either fungi or bacteria, yet 

 the trouble is apparently of fungous origin. In severe cases the 

 entire leaf or leaf tip becomes dead and brown. 



Specimens collected : New Braimfels, 1672, 1710. 



CAENATION. 



Root-rot {Fusarium sp.?). — This root disease was observed on the 

 carnation (Dianthus caryophyllus L.) both in the greenhouse and in 

 an irrigated garden. The smaller roots are destroyed and the larger 

 ones become badly disintegrated. 



Considerable loss results among young plants. 



Specimens collected : San Antonio, 1385 ; Austin, 1914. 



Rust (Uromyces caryophyllimis (Schrk.) Schrt.). — This fungus 

 was collected in a greenhouse in a single locality. The brown sori 

 were formed on the leaves and stems, but were not sufficiently abun- 

 dant to cause serious harm. 



Specimens collected: Austin, 2941, 3059. 

 226 



