Ornamental Plants 415 



kept as free from moisture as possible by free ventilation, 

 and still better by subirrigation. 



Fumigation of the houses in the fall before the intro- 

 duction of the plants serves to lessen infection from old 

 spores. 



Rust sori are occasionally the seat of attack by a Fu- 

 sarium,^^^ the result being a leaf-spot a centimeter or more 

 in diameter. 



Leaf-spot (Septoria dianthi Desm.). — The spots of this 

 disease — usually upon the leaves, sometimes upon the 

 stems — are circular or oblong, blanched or pinkish, and 

 purple bordered. Numerous small, black pycnidia lie in 

 the central region. The disease is especially abundant upon 

 the lower portion of the leaves and the sheaths. The diseased 

 part often becomes contracted, which results in bending and 

 curling of the leaves. Surface watering of the plants or 

 humid atmosphere tend to increase the trouble. 



Another Leaf-spot is due to Vermicularia subeffigiirata 

 Schw. — The bases of the leaves or the stems are usually the 

 points of attack. Black spore-bearing bodies appear in 

 abundance. Spraying with ammoniacal copper carbonate 

 has given good results. 



Alternariose ^^^ (Alternaria dianthi S. & H.). — This leaf 

 and stem disease has been reported as quite troublesome 

 in Connecticut, Pennsylvania, District of Columbia, North 

 Carolina, Missouri, and elsewhere. It consists of spots 

 mostly upon the leaves, som.etimes upon the stems, especially 

 at the nodes. These are strikingly characteristic, of ashen 

 whiteness, with the centers occupied by a scanty, to profuse, 

 black fungous growth. The diseased spot is dry, somewhat 

 shrunken, thinner than healthy portions of the leaf, approx- 

 imately circular, though often somewhat elongated in the 

 direction of the longitudinal axis of the leaf. When at 

 the node, the disease usually involves the bases of both of 

 the leaves, as well as the stem between them. As these 

 nodal spots age, the disease penetrates through the stem, 

 killing its tissue, which shrinks somewhat and becomes soft 



