DISEASKS OF VARIOUS CROPS IO43 



covered at the same time with the characteristic small black blisters. 

 The disease usually extends from the tip towards the base f the branches ; 

 sometimes the infection is confined to the internodes and the middle or 

 base. In these cases the portion of the branch above the infected part 

 dies and dries away, without showing the characteristic fructifications of 

 the parasite, which onl}^ form in the infected parts after their death. 



This disease is caused by the parasitism of a new species of Dothi- 

 deaceae, of which a description is given in the asccphore form under the name 

 of Scirrhia Bambiisae n. sp. and in the conidial form under the name of 

 Melanconium Bambusae n. sp. 



The disease was reproduced by artificially^ infecting B. mitis and B. 

 gracilis Hort. with the fungus. 



81 s - Ascochyta clematidina, on Stems and Leaves of Clematis. — gloyer, w. o 



in AVk' York Agricultural Expcnmcnt Sialioii, dcneva, T echnical Bulletin No. 44. pp. 3-I4. 

 Tlates I-IV. Washington, 1915. 



The rotting of the stems and mottling of the leaves of Clematis are due 

 to the fungus Ascochyta clematidina (Thiimen). 



The disease first occurs in the form of blotches on the surface of the 

 leaves. On drying, these blotches take on a dark chestnut colouration, 

 with red margins. From the leaf the mycelium makes its way down the 

 length of the petiole as far as the axil where it develops in the surrounding 

 tissue, forming a continuous zone of infection which causes the death of 

 the portions of the plant above this point. The parasite may also deve- 

 lop directly on damaged epithelium in the neighbourhood of the leaf axil. 



In both cases new buds and shoots continue to develop below the in- 

 fected region, until the mycelium of the fungus, spreading downwards to- 

 wards the base of the plant, eventually infects the whole of the aerial por- 

 tion and causes the death of the" host. 



Hibernation in the open, whether in artificial culture or in infected 

 vegetable debris, does not destroy the parasite. As soon as the temperature 

 permits, growth recommences. 



A. clematidina is easily isolated and develops readily in any of the usual 

 media. Inoculations with pure cultures (mycelium) into Clematis pani- 

 ciilata and C. Jackmanni gave positive results, and the mycelium derived 

 from artificially infected plants and inoculated on healthy specimens 

 readily reproduced the disease. 



A. clematidina is clearly distinct from other more common species and 

 inoculation experiments on pumpkins, beans, peas and elms gave negative 

 results. 



Sprays containing the spores of the parasite in suspension produce the 

 characteristic blotches on the leaves of Clematis, especially when the tempe- 

 rature is about 730 F. 



The following methods of control are recommended : i) transplantation 

 into the open when one year old, allowing sufficient space between the plants 

 foi access of air, sun, etc; 2) cutting and destroying all infected portions, 

 subsequently spraying lighth with fimgicides. The following mixture is 



