The diseases and pests of the rubber tree . CLARET-COLOURED CANKERPatch exposed by shaving PHYTOPHTHORA DISEASES 113 forms a scale whicli ultimately falls ofE. In these cases of self healing, the resulting damage depends entirely on theextent to which the disease has spread. If it has not pene-trated completely through the cortex a scale is formed, of a. Fig. 12.—Hevea Canker, caused by Phytophihora Faheri ;cortex cut away to show tlie discoloured areas. thickness depending upon the depth of penetration, but thewood is not exposed. But if it has penetrated through to thewood, a large open woun
The diseases and pests of the rubber tree . CLARET-COLOURED CANKERPatch exposed by shaving PHYTOPHTHORA DISEASES 113 forms a scale whicli ultimately falls ofE. In these cases of self healing, the resulting damage depends entirely on theextent to which the disease has spread. If it has not pene-trated completely through the cortex a scale is formed, of a. Fig. 12.—Hevea Canker, caused by Phytophihora Faheri ;cortex cut away to show tlie discoloured areas. thickness depending upon the depth of penetration, but thewood is not exposed. But if it has penetrated through to thewood, a large open wound, exposing the wood, is the conse-quence. In many instances the dead bark does not fall off. 114 THE RUBBER TREE ^h^- but is pushed off later by the growth of the callus underneathit from the edge of the wound. The most seriouscases of Claret-coloured Canker arethose in which the tree is attacked at the collar. Thedisease may then run rapidly round the base of the tree andkill it in a few weeks. When this canker attacks the thin, recently tapped,renewing bark, the diseased tissue often retains the colourof the early stage, it is yeUowish-grey, and does not becomeclaret-coloured; but where, as usually happens, it extendsfrom the renewing bark into the untapped area below it,the patch in the latter assumes the typical claret i
Size: 1249px × 2000px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, bookidcu3192400285, bookyear1921
