458 THE CANADIAN HORTICULTURIST. 



NOTES FROM THE BIOLOGICAL DEPARTMENT, 



Ontario Agricultural College. 



'HE following- notes bearing on horti- 

 cultural topics are based partly on 

 the past season's observations, and 

 '^pi partly on the experiences of previ- 

 ous seasons. 



Our correspondence with fruit-growers 

 from various parts of the Province has been 

 unusually heavy this year, and there appears 

 to be a g-rowing- demand for more informa- 

 tion regarding spraying-, and insect and fun- 

 gous troubles. 



FRUIT DISEASES. 



It is acknowleged by nearly every fruit- 

 g-rower that the fung-ous diseases which are 

 usually so destructive have not been very 

 severe this past season, and have given but 

 little trouble. This happy circumstance has 

 resulted from the peculiar seasonal condi- 

 tions. The early summer was very dry, and 

 the moist conditions which ordinarily sur- 

 round the spores blown from one plant to 

 another were absent, and germination be- 

 came impossible. Mildews on the grape 

 were rare, but in one or two localities the 

 gooseberry mildew was difficult to control. 

 Apple scab was not serious, and leaf-spots 

 were not common. 



The dryness of the season, which was so 

 unfavorable for the germination of spores 

 and the development of fungous diseases, 

 produced some peculiar features in tomatoes^ 

 pears and peaches. Many of these fruits had 

 peculiar indentations, as if made by the 

 pressure of a strong fing-er. Sometimes 

 three or four of these were found on single 

 pears and peaches. These indentations were 

 very common on the pear, and no doubt in- 

 terfered with its sale on the market. 



On examination the tissue immediately 

 beneath the indentation was found to be 



Fio. 1941. 

 Canker Worm. 



drier than the remain- 

 ing tissue, and unlike 

 anything produced by 

 fungi. As the spot 

 increased in size the 



area of dry ti-^sue also increased, so that the 

 condition was simply one of drying up of 

 tissue in certain localized spots. 



In the case of the tomato the disturbed 

 area was very plain, and resembled the early 

 stages of the tomato rot (Macrosporium). 

 There was a diseased, sunken, circular spot 

 covered by a toug-h grey skin, beneath which 

 the pulp was dry. As the area increased in 

 size bacteria gained an entrance and a rot- 

 ting took place. 



It is difficult to state definitely the exact 

 cause which led to such a disturbance, but 

 probably the chief factor was a diminution 

 of moisture supply to the grown fruit at a 

 time when evaporation from the fruit was 

 still active. 



FALL ORCHARD CLEANING. 



Much can be said in favor of an annual 

 fall orchard cleaning, althoug^h many of our 

 fruit-growers are indifferent in this matter. 

 Aside from the fact that there is more leisure 

 after the fruit has been gathered than in the 

 rush of our early spring when so many odds 

 and ends must be attended to, there are 

 many urgent and convincing- reasons why 

 our orchards should be very carefully cleaned 

 of rubbish and litter during- late fall and 

 early winter. Many insects and fungfi pass 

 their resting stag^es during the winter among- 

 the grass and fallen leaves. Hedg^es and 

 fence-corners are favorite hiding places for 

 many destructive insects, and vvhenever 

 possible these places should be searched, 

 and the collected rubbish burned. If this 



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