Ornamental Plants 437 



weak plants, poor stock, poor beds, are predisposing con- 

 ditions to disease. 



To avoid the disease the houses should be kept scrupu- 

 lously clean, only strong stock used, infested material picked 

 and burned, and insects banished. Close attention must 

 also be given to ventilation, heating, shading, and watering. 

 The soil should be removed each season and every means 

 used to produce strong resistant plants. Other leaf-spots are 

 due to Cercospora violce Sacc, Phyllosticta violce Desm. and 

 Marssonina violce (Pass.) Sacc. No pycnidia are present, but 

 the centers of the spots are darkened by the presence of 

 hyphae. 



Anthracnose ''■'^ {Colletotrichum violce-tn col oris RES.). — 

 This blight has been noted in many states. It is characterized 

 by the appearance of dead, black-bordered spots on the 

 leaves and petals, thus disfiguring the flowers, and affecting 

 the production of seed, or even bringing premature death 

 to the plant. 



Thorough and frequent spraying with Bordeaux mixture 

 is advocated. 



Wilt "^^^ (Fusarium violce Wolf). — This was noted as of 

 economic importance in Nebraska, where it caused sudden 

 dying of apparently healthy plants. Slightly sunken areas 

 were evident on the stems just above the ground, and the 

 roots were reduced to mere stumps. 



Rust (Puccinia violce (Schm.) DC). — One of the most 

 common of pansy diseases is this true rust which affects all 

 aerial parts of the plant. It is recognized by its sori. 



Downy-mildew (Peronospora violce De Bary). — The 

 downy-mildew is in general character like that of the grape. 

 The spots are indefinite, and affected plants droop and die. 



Anthracnose {Glceosporium violce B. & Br.). — The an- 

 thracnose often begins at the edge of the leaf, as an irregular 

 discoloration which extends inward, eventually blighting the 

 whole leaf. 



Root-rot (Thielavia). — Affected plants are stunted and 

 yellow. The underground parts show numerous dark spots 



