1904.] 



Peach Leaf-curl. 



241 



the leaves are young, the disease at once appears, and its rapid 

 spread is much favoured by alternating short spells of warm and 

 cold weather. 



The injury caused by the disease consists of the dropping of 

 the fruit at an early stage and the strain on the tree due to the 

 growth of a second crop of leaves about midsummer, which 

 usually remain free from disease. In the case of nursery stock, 

 consecutive attacks for three or four seasons usually kill the 

 tree, or stunt its growth to such an extent that it is practically 

 valueless. 



In the United States it is contended that " curl " can be held 

 in check by spraying with a fungicide alone ; unfortunately, 

 repeated experiments have proved that this is not true for this 

 country. In the case of diseased trees, all the terminal shoots 

 bearing infected tufts of leaves should be removed and burned ; 

 diseased fallen leaves should also be collected and destroyed. 

 By removing the diseased shoots one source of infection, namely, 

 that arising from the spores formed on leaves originating from 

 such, is removed ; besides, there is no advantage in retaining 

 such contorted twigs on the tree. 



A second source of infection depends on the presence of 

 spores that have passed the winter in the angle formed between 

 leaf-buds and the branch on which they grow, inside the bud- 

 scales, or in minute cracks in the bark. Such spores should be 

 destroyed by spraying with Bordeaux mixture, commencing 

 when the buds show the very first indication of swelling. Two 

 sprayings, at intervals of ten days, if thoroughly well done, 

 should suffice. The leaf-buds should not be sprayed after they 

 begin to expand, or the foliage will be destroyed or injured. 



The mixture should be made with 20 lb. of sulphate of copper 

 and 10 lb. of lime to 100 gallons of water. The sulphate of 

 copper must be dissolved in a vessel of cold water, and the lime, 

 which must be pure and fresh, slaked in another vessel. The 

 contents of the two vessels should be poured together into a tub 

 and the proper quantity of water added. Sulphate of copper 

 solutions are poisonous, and tubs, pails, or other vessels which 

 have contained the mixture must not be used for other pur- 

 poses. 



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