1847.] Blight in Jlpple and Pear Trees. 9 



that the new wood, or the latest growth, should suffer most. 

 Thus the young of" peach trees in some locations is often destroyed. 

 The ends of limbs are dead. But not so in blight. The disease 

 rarely begins with the extremity, but usually in the middle of a 

 branch, as has been already described, and this not until after the 

 limb has been covered with a vigorous growth of leaves and new 

 wood, or an extension of its branches has taken place. In such a 

 case it can hardly be supposed that it is really the same sap which 

 has been supposed to have been frozen in the opening of spring, or 

 during the winter. This sap has already been expended in the 

 growth of new parts, and a new formed sap supplies the plant with 

 this circulating fluid. 



3. It seems more consonant with facts, to infer that M^hen a 

 vegetable is destroyed, immediately or ultimately, by frost, that 

 death takes place by injury which the solids sustain, rather than 

 by the injury of ihe fluids. The change in this case in the fluids 

 is an effect, and not a cause — the solids themselves being the 

 organs by which healthy fluids are generated, though it still re- 

 mains true that when the fluids are imperfectly formed, or are 

 changed in their essential properties, that death or injury to the 

 structure must necessarily follow, notwithstanding the solids are 

 in a healthy state. The foregoing considerations are sufficient 

 with us for the rejection of the theory which maintains that frozen 

 sap is proximately the cause of blight in fruit trees. To these we 

 might still add other considerations which go to disprove it. So 

 we dissent, also, from the views of the author of this theory in re- 

 gard to the proposed remedy, viz., a coating of whitewash. This 

 seems to have been proposed from a misapprehension of the na- 

 ture of the coating itself; for, in fact, so far as the coating ope- 

 rates at all, it must promote rather than retard the freezing of 

 the sap. An earthy material, of the nature of whitewash, is a 

 better conductor of heat than the porous and partially dry cuticle 

 itself The remedy which has been proposed for the treatment of 

 blight, is simple, but strikes not at the root of the evil. The limb, 

 when found affected, may be removed; it is no longer a living 

 part of the vegetable system. A close inspection of the bark, 

 with incisions of the cuticle, will show the extent of the disease, 

 and all that is diseased may be removed at once. It does not fol- 

 low, however, that because a limb is not removed that the whole 

 tree will certainly die, for instances do occur where the tree lives 

 on with its dead branches remaining. The knife, however, had 

 better be freely applied, for the limb is irreparably gone, and the 

 fear that contaminated fluids may occur, by which the disease is 

 extended, should rather stimulate us to the excision of the member. 



The period when the blight begins is about the middle of June, 

 after there has been a considerable part of the growth of wood for 



