CHESTNUT DISEASES 147 



all diseased trees in spot infections somewhat distant from the 

 generally infested areas and the surrounding of the area already 

 invaded, by a zone from which all chestnut trees were to be cut 

 and removed. Much effort was expended in 1911 and 1912 

 to locate and map the regions in which this method would be 

 put into effect. Trial areas were located and all diseased trees 

 were cut, the timber peeled and the refuse burned. The 

 enormous effort involved in carrying out such a plan to control 

 the disease seemed far too expensive and the results too prob- 

 lematical to warrant their continuance. Pennsylvania, how- 

 ever, by the appointment of a special commission, attempted 

 to carry out the eradication methods in that state, but discon- 

 tinued the work in 1913 after two years' trial. Since that time 

 the canker has continued its destruction and is gradually ex- 

 tending its range into the northern limits of the chestnut in 

 the New England states, western New York and Ohio and into 

 the southern Appalachians, threatening the total extinction of 

 the tree. 



The attempt to control chestnut canker in individual trees, 

 when the expense of siu-gical methods is warranted, may be 

 successful. By the ordinary methods of canker eradication, 

 the diseased areas may be removed. Especial care is necessary 

 in order completely to remove the fungus. The bark should 

 be cut away at least an inch beyond the apparent edge of the 

 canker and the wood beneath the area of bark thus removed 

 must be chiseled out to a depth of an inch. Coal-tar dressing 

 then should be applied to the exposed wood and bark. After 

 all the cankers are removed, careful watch must be kept for 

 the appearance of new cankers. If the tree is large and has 

 rough bark, the chances of discovering all the diseased areas 

 in time are small. 



The Japanese varieties are sufficiently resistant, if pure stock 

 and not grafted on American roots, to warrant their use as 

 orchard-trees. The crossing of the Japanese and Chinese with 



