240 Journal of Agricv.liural Research voi. iv. N0.4 



remain disease-free. The fungus can live as a saprophyte on dead vines 

 kept out of doors in baskets, and under such conditions it has lived over 

 two winters, producing pycnidia and viable spores in abundance. This 

 indicates that the same beds should not be used for clematis in successive 

 years. 



On hybrids the disease is primarily a greenhouse trouble and can be 

 overcome by the use of cuttings made from healthy plants. A light 

 spraying with the soap-and-sulphur mixture has proved satisfactory in 

 the greenhouse. It could readily be applied also in the forcing frames. 

 Diseased leaves or stubs should be removed as soon as discovered so as 

 to prevent the fungus becoming established in the tissues. 



The retail purchaser of clematis can prevent the dying of plants by 

 taking proper simple precautions. The plants should be placed in good 

 soil, well drained and on a sunny exposure. As soon as the new shoots 

 have formed the old vine tissue should be carefully cut away close to the 

 new shoots, removing all traces of the brown, discolored wood in which 

 the fungus is to be found. Proper ventilation is obtained by training 

 the plants to a strong trellis. 



SUMMARY 



(i) The stem-rot and leaf -spot of clematis is caused by the fungus 

 Ascochyta clematidina (Thiimen.). 



(2) The plants are killed by the growth of the fungus down the petiole 

 into the stems, thus girdling the plant at the node. The stem may 

 be girdled also by the lesions anywhere on the internodes. Dead stubs 

 left on the vines are a means of holding the disease over a period of 

 time. New shoots may be formed below the girdled region, but the 

 downward progress of the fungus ultimately kills the plant if the diseased 

 tissue is not removed. 



(3) Overwintering out of doors does not kill the fungus in cultures 

 or on dead vines. Whenever the temperature permits, the fungus 

 resumes its growth. 



(4) The fungus is readily isolated and grows well on the media gen- 

 erally employed in the laboratory. 



(5) The disease has been successfully produced by inoculating C. 

 paniculata and C. jackmanni with the mycelium from pure cultures. 

 The fungus has been reisolated from such inoculations, and with it 

 lesions were again produced on other vines similarly treated. 



(6) A. clematidina is not related to other common species of the 

 genus Ascochyta, for inoculations made in growing stems of bean, pea, 

 muskmelon, pumpkin, eggplant, and the young shoots of elm gave 

 negative results. 



(7) Spraying the plants with spores will produce the leaf-spot. More 

 spots are produced when the spores are placed on the lower surface of 



