68 PROTECTION OF PLANTS — 1922-23 



3. Septorial leaf spot — {Septoria pceonioB West var. berolinensis Allesch.) 



This undoubtfedly is a very trou'blesome disease of the peony, affecting 

 both leaves and stems and was first noted at Macdonald College in Aug., 1920, 

 The amount of infection upon the leaves ranged from to 85% on different 

 varieties, and the average for all varieties, was estimated at 20% for the fall 

 of 1921 and 1922. Usually where heavy leaf infection occurred severe stem 

 infection was also found. The spots on the leaves are small, limited by veins 

 more or less round, yellowish-brown, with pale or ashen gray centres, purple 

 bordered and usuallj' showing zonation. The centre is usually somewhat 

 sunken, shows a tendency to drop out and w^hen this happens various Alter- 

 narias' are invariably found in the spots. On the stems the spots are whitish 

 purple-bordered and tend to become elongated. 



Last spring this diseasp was first observed apon the young stems of a 

 few plants on the 10th of June, and was the first disease to make its appearance. 

 From the stem it spreads to the leaves, first infecting the leaves toward the 

 interior of the plant due to moist conditions prevailing there. This as well 

 as other diseases spread very rapidly during the rest of June, and the first 

 half of July during which period there was a good deal of rain. From this 

 time very little new infection occurred until the middle of September following 

 a period of considerable rain. 



The spores are produced in brown gregarious pycnidia w^ith a distinct 

 ostiolum. They are described by Saccardo as being fusiform, curved, accu- 

 minate at both ends, indistinctly multinucleated, hyaline 25 — 30=1^' — 20. 



Spores can be found in quite young lesions and in great numbers and it 

 was quite easy to isolate the fungus in pure cult\ire. This is the second time 

 that this fungus has been reported for America, it being first reported by 

 Anna E. Jenkins in Pathological Herbarium Notes issued by the United States 

 Dept. of Agriculture, Bur. of Plant Industry. No. 2, Sept. 1st, 1921. This 

 fungus has been isolated and infection experiments and further studies will 

 be carried out this winter . 



4. "Mosaic" disease. 



This is found upon a few varieties, but cannot be considered to be a trouble- 

 some disease. 



5. Two leaf spots of unknown cause. 



(a) A disease characterized by irregular lead-white spots with a compara- 

 tively broad purple border. These spots are for the most part confined to 

 the upper surfaces of the leaves and do not show or only sHghtly on the under 

 surfaces. When showing through the under surface they appear as light 

 brown spots. Scattered, black, more or less erumpent pycnidia or peritheria 



