838 EXPERIMENTAL FARMS 



5 GEORGE v., A. 1915 



Where silver leaf exists it would be advisable to first try a spray of Black Leaf 40 

 or lime-sulphur just before the leaf buds open. If the disease persists it is evident that 

 it is not caused by mites. 



Dr. Waite, in charge of the fruit disease investigations at Washington, informs me 

 in a letter that the mite observed may be identical with that described in Bulletin 

 283, Geneva, N.Y., Agricultural Experiment Station as Phyllocoptes schlechtendali. 



Meanwhile the investigations into the nature of this disease are being continued. 



HOUSE-PLY FUNGUS. 



A fungus destructive to hotise-flies. — Since it has become recognized that the 

 common house fly is a potential source of danger to the public health as a carrier of 

 pathogenic micro-organisms, the question of an effectual and practical method of 

 exterminating, or at least reducing the prevalence of this insect during the summer 

 months, has attractal considerable attention. 



As a means towards the solution of this problem, the study of certain organisms 

 of fungal or bacterial nature liable to cause an epidemic among flies seems most impor- 

 tant. As time permits, such investigations have been conducted by the Dominion 

 Botanist. Among the commonest of fungus diseases of flies is the Empusa Muscae 

 Cohn, which kills off a considerable number of flies each year. Flies killed by this 

 fungus are conspicuous by the life-like position they retain when killed and the white 

 spore-dust surrounding the dead bodies for a short tlistance. At the present time, 

 while we have succeeded in infecting flies very readily with the fungus spores and thus 

 causing death among them, our experiments came to an end^ prematurely when we 

 failed in January to secure more flies for infection. This experience was reported 

 for several seasons, but the end in view warrants further researches in this subject. 



The value of organisms causing epidemics among noxious insects is best demon- 

 strated by the grasshopper bacterium Coccohacillus acridionim. successfully isolated 

 and tested by Dr. d'Herelle of the Pasteur Institute of Paris. 



II.— EXPERIMENTAL WOEK. 



As indicated in our last report, the experiments on growing potatoes on 4 acres 

 of land " free from disease, or as free from disease as possible," have been continued 

 during the last season. The potatoes produced were a very good crop and of splendid 

 keeping quality. Five varieties have been grown which gave a total yield of 866 

 bush, and 34 lbs. 



The cultural work in the field has been carried on by Mr. D. D. Gray, Farm 

 Foreman, while this Division had charge of the treatment of the seed tubers and the 

 spraying operations throughout the season. 



• POTATO-PITTING EXPERIMENTS. 



Owing to the often considerable losses from storing potatoes in unsuitable root- 

 houses or cellars, as referred to in our last year's report, we have tried the experiment 

 of storing the t\ibers'in a pit on the level ground. The wintering of potatoes in pits 

 may prevent the losses from decay and prove a cheaper means than the building of 

 cellars or houses for the purpose. Fifty bushels of four varieties were wintered in a 

 pit constructed in the following manner: — 



Ottawa. 



