REPORT OF THE SOCIETY 60 



can be found on many of these lesions. Examination has shown these fraiting 

 striictutes to belong to Phyllosticta, Pleospora, Septofia, and possibly one or 

 two other genera. An undetermined Phyllosticta is, however, most commonly 

 associated with this disease. Various fungi have been isolated in pure cultures 

 from these spots d,nd inoculation experiments will be carried out. 



This disease was first noticed on the 26th of July. It did not increase 

 very rapidly and the amount of leaf infection this fall was estimated at 2%. 

 See fig. I. 



(b) Another leaf disease characterized by definitely limited irregular, 

 yellow spots with a dark border in most cases was quite common on a few 

 varieties. The spots vary from 2 to 8 mm. broad. 



The fungus most consistantly associated with this disease is a species of 

 Alternaria. This has been isolated and artificial inoculations were carried 

 out last winter upon two plants in the green house and again last spring upon 

 plants in the field. By keeping the plants under bell jars for two or three 

 days after the inoculum was applied, it was quite easy to get infections and 

 typical spots begin to develop in four or five days. The inoculum used was 

 a suspension of spores in distilled water appHed as a spray or a portion of agar 

 from a test tube culture with mycelium and spores placed upon the leaves. 

 From most of the lesions so produced the Alternaria was again isolated in pure 

 cultUlre. This is quite strong proof of the pathogenicity of this fungus. As 

 only two plants were available last winter, it was impossible to have sufficient 

 controls to work with and the field inoculations are not considered to be too 

 reliable as the plants may have been inoculated from some other source. With 

 more plants in the green house available this winter it is hoped that we will 

 be able to thoroughly establish proof of the pathogenicity of this fungus. 



6. Disease of the underground parts. 



A plot of peonies at Senneville last summer was very heavily infected with 

 a disease of the underground parts which was confined chiefly to the roots. 

 The plants were set out last spring on land which had been used for some time 

 as a garden. 



The tops showed a marked wilting and dying with a blackening of the 

 stem passing upward from the ground. A number of plants produced new 

 branches and leaves in the late summer or fall. The roots on plants in which 

 the tops were dying or dead were themselves dead or dying. The entire under- 

 ground portion was usually blackened to a considerable extent. It is believed 

 to be a Fusarium root rot as growth of Fusarium could be found on most of 

 the roots and this was isolated in pure culture. 



