THE FAILURES OF THE LARCH. 63 



penetrate to the lower and earlier leaf-covered portions of the 

 tree, when on its upper extremities the leafage is yet undeveloped, 

 and the sap-flow comparatively limited as well as languid. On 

 the. other hand, late autumn frosts are those most productive of 

 top-rot, fx-om the upper extremities being the latest in maturing, as 

 well as the least protected. And it may be here remarked that 

 this most common form of top-rot, and that to which the name is 

 most generally applied, is not to be confounded with the before-men- 

 tioned, which proceeds from internal decay or hearf>rot ; whereas 

 in both the forms of failure (canker and top-rot) here associated, 

 the heart timber remains comparatively sound, unless the trees 

 have been affected with heart-rot prior to suffering from either 

 early or late frosts, a by no means uncommon occurrence. 



Canker and top-rot may be induced at all stages of larch growth, 

 being occasionally observable in one-year-old plantations, but both, 

 and especially the former, become comparatively scarce after from 

 forty to fifty years of age. Cure for these injuries being out of 

 the question, and cases of that recovery being very limited as well 

 as uncertain, the best procedure is to clear them away, as recom- 

 mended under the last head, and replant with other kinds suitable 

 for the soil and situation. And the only prevention for the 

 wide spread and heavy losses that occasionally arise from canker 

 and top-rot lies in the judicious selection of soils and situations in 

 which to plant young larches, avoiding warm southerly exposures 

 that excite their too early spring growth, and more especially all 

 low, flat, moist-surfaced districts, that are subject to cold ground 

 fogs and hoar-frosts. These severe early and late frosts are not of 

 frequent occurrence, but when they do happen they are occasion- 

 ally very disastrous. 



The following examples may be adduced in confirmation of the 

 forestated conclusions regarding the cause of canker and top-rot in 

 the larch : — 



About the middle of May 1837, I left Huntly for Edinburgh, 

 where I had been conducting planting operations on the Duke of 

 Richmond's estates, the most extensive, I believe, that have ever 

 been done within the same space of time. Proceeding by the 

 " Defiance " coach to Aberdeen, continuous frost, with occasional 

 snow showers, lasted throughout the day. At night the frost be- 

 came much more intense ; next morning a covering of snow con- 

 cealed the ground surface and hung thickly on the trees, especially 

 on the larches, which were then in full leaf. By the time we 



