62 THE FAILURES OF THE LARCH. 



dry rottenness to total decay and hollow-heartedness or pumping ; 

 the decrease in the width of the annual wood-layers being propor- 

 tionate to the increase of rottenness till arrested by death. These 

 symptoms occur at all ages, but are most frequent between ten 

 and thirty-five to forty years, and are attributable to occasional 

 droughts, as well as occasional over-saturation ; to fungoid attacks 

 on the roots such as emanate from decaying remains in ground 

 previously occupied by Scotch fir ; and by lopping off or other- 

 wise destroying the roots. In fact, by anything that thoroughly 

 checks or materially weakens the root action, that in those of the 

 larch when once fully stopped, is incapable of resuming sap 

 circulation, hence these must inevitably decay, when they first con- 

 vey their rottenness to those parts of the stem that are in most 

 direct communication with them, from whence it spreads with 

 rapidity proportionally to the extent of the root injury. The cor- 

 rectness of these remarks being assumed, it follows that the only 

 prevention of dry-rot is to avoid planting larch in places likely to 

 produce it. The only remedial measures that can be adopted — for 

 cure there is none — are cutting down the trees when it first 

 appears, and replanting the ground with other more suitable kinds. 



II. Surface-rot, cancer, cankering or blistering, and top-rot 

 presents the appearance of a dark, flattish, thickish margined 

 bruise or cancerous-like wound, from which more or less thickish 

 resinous matter exudes. Frequently several of these exist on one 

 stem, and they occasionally include the base of the branches, so 

 as to deprive them of vitality. Sometimes they are also to be 

 found on the branches themselves. Wherever they appear, the 

 injury to the stem or branch has only been at first partial, a suffi- 

 cient portion having been left sound to admit of the sap flowing 

 beyond ; and when only slightly affected, the tree often resumes 

 and maintains a healthy growth, so as to'nearly, if not entirely, ob- 

 literate all traces of the injury. If, on the other hand, the injury 

 is of such an extent as to prevent the further ascent of the sap, 

 all above speedily dies without presenting the appearance of 

 blistering, but merely that of dead tops or top-rot. 



Canker and top-rot are due to the effects of late spring frosts 

 occurring after the sap-flow and growth is in full progress, and to 

 early autumn frosts setting in before the growths of the season 

 are fully matured. The late spring frosts are, however, those most 

 generally productive of canker, from the facility with which they 



