442 CONNECTICUT EXPERIMENT STATION REPORT, 1912. 



PREVENTIVE EXPERIMENTS. 



Earlier Experiments. Murrill tried to control the chestnut 

 disease, when it was first discovered at the New York Botanical 

 Garden, by cutting down and destroying the badly infected trees 

 and by cutting out cankers on those less seriously injured. He 

 found this did not prevent its further spread. Writing in 1908, 

 he (48) says: "Preventive .measures have apparently not 

 affected it in the slightest degree. Pruning of diseased branches 

 has evidently failed to check it even in the case of very young 

 trees. Branches have been carefully removed, and wounds 

 covered, leaving trees apparently entirely sound, but upon 

 inspection a few weeks or a few months later, they would be 

 found badly diseased at other points." Merkel, at the New 

 York Zoological Park, also tried to control the trouble by cut- 

 ting down the badly infected trees and by spraying with Bor- 

 deaux mixture, but little or no benefit resulted from his efforts. 



Metcalf undertook experiments to control the trouble on 

 Long Island in a region where it was very bad. In 1909 he 

 and Collins (36) say: "At present it is impossible definitely 

 to record general beneficial results from any of the sprayings 

 which have been undertaken or have been under observation. 

 This may in part be due to the fact that it is yet too early to 

 judge satisfactorily of the results,, and in part perhaps to the 

 infrequency of sprayings. * * * Almost the only treatment 

 that can at present be safely recommended as surely retarding 

 the spread of the disease, to a greater or less extent, is one 

 which will never be of practical use except in the case of 

 orchard trees or certain valuable ornamental trees. It consists 

 essentially in cutting out the infected branches or areas of bark 

 and carefully protecting the cut surfaces from outside infection 

 by means of a coat of paint or tar. This cutting must be 

 thoroughly done and the bark of every infected place entirely 

 removed for a distance of at least an inch (when the size of the 

 branch permits) beyond the characteristic, often fan-shaped, 

 discolored area produced by the growing fungus in the inner 

 bark." In a later report, they also advocate that when the inner 

 bark is badly infected "at least two or three annual layers of 

 wood beneath the diseased bark must also be gouged out." 



Later Experiments. In a bulletin published in October, 1911, 

 Metcalf and Collins (38, p. 10) advocate fighting the chestnut 



