DISEASES OF THE CHESTNUT AND OTHER TREES 85 



bark disease in at least two States has been made the occasion for 

 a general forest survey. Everywhere it will prove the occasion 

 for more careful management of the surviving trees. In localities 

 where the chestnut is already past saving, this species must be 

 discriminated against (13). While change of management of 

 chestnut woodland may not affect the course of the disease, except 

 in so far as it involves cutting out, constructive forestry is bound 

 to be stimulated by the work done on this disease. Methods of 

 control of this and other forest diseases which are visionary now 

 will be in daily use in twenty years. We do not realize how rapidly 

 forestry in the Eastern States is becoming as intensive as that of 

 Europe. 



Tree surgery. Extensive experiments, performed mostly by 

 Prof. J. F. Collins (12, 13), indicate that the life of small ornamental 

 and orchard chestnuts can at least be prolonged by a cutting out 

 system somewhat similar to that used in the control of pear-blight 

 (3, 4). No such experiments have proved successful, however, 

 when performed on large thick-barked ornamental trees, mainly 

 on account of the difficulty of detecting small lesions in the thick 

 bark. 



Tree medication. The possibility of controlling disease in trees 

 by special fertilization (24) or by direct chemotherapy (25, 26) — 

 the introduction of chemicals or immunizing substances directly 

 into the tree — has long been a fascinating ideal, but so far rather 

 barren of results. The method has been discredited by the number 

 of fake remedies which are supposed to be applied in this way. 

 Nevertheless, the basal idea is fundamentally sound. It is inter- 

 esting to know that Dr. Caroline Rumbold, one of the investigators 

 in the employ of the Pennsylvania Chestnut Tree Blight Com- 

 mission, is making extensive experiments along this general line. 

 From her work very valuable scientfic results are to be expected, 

 whether the method ever becomes a practical success or not. 



Breeding resistant trees. The resistance of the Japanese and 

 Korean chestnuts suggests that if resistant individuals of these 

 species were crossed with the American and European chestnuts, 

 hybrids might be produced with the desirable nut characters of 

 one parent and the resistance of the other. So far no resistant 

 individuals of the American chestnut have been found. Trees 



