332 GREENHOUSE MANAGEMENT. 



of the leaves, when they are oblong or semi-circular. 

 The centers of the spots are grayish-brown in color, with 

 margins that have a purplish tinge (Fig. 110, a). Upon 

 the light portion of the spots, minute black dots will 

 soon appear ; the mycelium of the fungus has developed 

 within the leaf, and these points are 

 projections from the flask-shaped 

 conceptacles in which the spores 

 are formed (Fig. 116, d). An en- 

 larged spore case is shown at b and 

 the spores themselves are seen at c. 

 The spores are quite slender and, 

 enclosed in a viscid substance, ooze 

 out through the opening, to be dis- 

 solved in water and scattered to the 

 fig. ii6. spot disease neighboring plants, or they may be 



OF CAKNATIONS. , , , , „ . », ' , , 



taken up by currents ot air atter the 

 water has evaporated. The watering of the plants with 

 a strong stream of water, through a hose, will be likely 

 to scatter the spores, and if they fall in a drop of water 

 on a carnation leaf, they will quickly germinate and 

 cause other spots. If the flower stems are affected, the 

 growth is likely to be checked and on the leaves the 

 effect is to contract and weaken them, the spots turn 

 brown and they become bent and twisted (Fig. 117). 



If taken in time, when the disease first appears, the 

 application of fungicides will tend to keep it in check. 



ANTHKACNOSE OF CARNATIONS ( Volutella diantlli). 



The nature of this disease was pointed out in 1891, 

 by Dr. B. D. Halsted, who thought it to be Colleto- 

 trichum diantlli ; the later investigations of Prof. Atkin- 

 son, however, would seem to show that it can more 

 properly be referred to the genus Volutella. It causes a 

 rapid decay of the affected portions and the warmth and 

 damp of the cutting bench seem particularly favorable 



