Metcalf: The Chestnut P.ark Disease 



A CHESTNUT GROVE IN CHINA. 



The Chinese chestnut (Castanea mollissima) has been cultivated for centuries by the Chinese 

 horticulturists. This photograph, sent in by Frank N. Meyer, agricultural explorer 

 of the United States Department of Agriculture, shows the low-branching, open-headed 

 habit of the species. Scars on the trunks caused by attacks of the bark disease can be 

 seen plainly. Near San tun ying, province of Chili, June 1, 1913. (Figure 1.) 



from the northwest corner of Susque- 

 hanna County to the eastern border of 

 Clearfield County and on to the south- 

 west corner of Ftilton County. West 

 of this line the advance infections were 

 cut out by the Pennsylvania Chestnut 

 Tree Blight Commission. The disease 

 has not yet been found in Ohio or 

 Indiana. In general it appears to spread 

 northeastward and south westward, fol- 

 lowing the direction of the ridges of the 

 Appalachians, much more rapidly than 

 westward, across the ridges and valleys. 

 Scattering infections occur outside of 

 this area. Of these, the outposts are two 

 infections on planted chestnuts in 

 Franklin and Androscoggin Counties, 

 Maine, and one infection in a nursery in 

 North Carolina. There is reason to 

 suppose that the North Carolina in- 

 fection, and an orchard infection in 

 British Columbia, owe their origin to 

 trees imported directly from the Orient. 



The disease has not yet been reported 

 from Europe, but its appearance there 

 must be only a question of time. 



It is difficult to estimate the financial 

 loss which the above distribution rep- 

 resents, as we have no exact statistics 

 on the value of standing chestnut tim- 

 ber. The estimate of $25,000,000 made 

 in 1911 as representing the loss up to 

 that time was probably much too con- 

 servative. But the total loss to date is 

 insignificant compared with the loss 

 which will ensue when the disease 

 attacks the virgin chestnut timber of the 

 South Appalachians. The bark disease 

 has killed all the chestnut trees in those 

 localities where it has been present long 

 enough, and there is not now the 

 slightest indication that it is decreasing 

 in virulence or that the climate of any 

 region to which it has spread is having 

 any appreciable retarding effect upon 

 it. Insects which eat the pustules of the 



