A REVIEW OF OPINIONS ON PEAR TREE BLIGHT. 



497 



stance, as hard winters, with long cold 

 springs, giving us good pears and leaving 

 us sound trees, while a warm February, fol- 

 lowed by a cold March, destroys our trees. 

 We have, long been acquainted with this 

 much of vegetable physiology, that the bark 

 forms on its interior surface longitudinal 

 fibres, the same as sap wood, and by this 

 means adheres to the main sap wood, be- 

 coming one and inseparable, and that when 

 a certain temperature, say that of April, be- 

 comes steady, that those same fibres, hav- 

 ing lost their colour, throw out juices and 

 form fibres differently disposed and coloured, 

 or bark. It is a well known fact that the 

 finest kinds of pears are introduced from a 

 milder climate than 39 degrees, and there, 

 fore are very sensible to both cold and heat. 

 They are trees that abound with juices, as 

 may be seen by the numerous scions that 

 they fling up around them. If the later 

 part of winter or early spring is warm, 

 these juices are set afloat, especially if the 

 ground is rich and cultivated. In this de- 

 gree of light and heat, the bark begins to 

 form a separation to take place from the 

 new made sap wood, and in a few days 

 winter ; returns upon the tree, or in other 

 words February has been spring and March 

 winter; an imperfect bark is thus separated 

 from the mother white wood and sickens, 

 and, as heat is farther applied, dies. It is 

 sometimes the middle of the summer be- 

 fore the damage is developed." And the 

 writer states the following facts, that he has 

 known only two sets of healthy pear trees, 

 and they were neither manured nor dug 

 round for years; the suckers were permitted 

 to grow undisturbed, and the grass sur- 

 rounded them unbroken ; and that they 

 were not only perfect, but bore fruit when 

 others failed. He had two healthy pears, 

 " the Vergalieu, the one was choked with 

 grass, and the other so surrounded with sci- 



ons as scarcely to admit of approach." He 

 removed the " scions," and dug and ma- 

 nured the ground, and both perished ; and 

 he gives another instance within his knowl- 

 edge, where the same effect was produced 

 by similar treatment. He supposes, in the 

 first instance, "that the abundant juices 

 were restrained," and recommends that the 

 trees, after they have arrived at the fruit bear- 

 ing period, should be untouched by the knife, 

 and " suffered to vegetate naturally." He 

 also states his belief that the application of 

 any composition, such for instance as white- 

 wash thickened with ashes and cow dung, 

 spread upon the body and larger limbs, in- 

 stead of being beneficial, " might be the ve- 

 ry cause of death," and advises the trial of 

 such experiments as will prevent '•' the too 

 free and early circulation of the sap." 



Unimportant as it may seem, whether 

 the disease is produced by the freezing of 

 the sap in the autumn or spring, yet in our 

 apprehension, the writer committed serious 

 errors as to the remedies to be used to guard 

 against it, by simply mistaking the time 

 when the injury is sustained. We have 

 no doubt that the trees he refers to as per- 

 ishing, which were of a variety by some 

 supposed to have arrived at or near the lim- 

 its of its duration, Avere neither attacked by 

 an epidemic, nor by a disease produced by 

 reason of " long continuance," but destroy- 

 ed in consequence of the means taken to 

 promote their growth. The removal of the 

 grass, "unbroken for years," and of the 

 abundant quantity of suckers, which sur- 

 rounded them, (to the extent of nearly forty 

 feet,) and the application of manure, occa- 

 sioned a vigorous late growth that became 

 fatal. " The only severe case of blight in 

 gardens here," says Downing, " during the 

 summer of 1844, was in the head of a Gi- 

 logil pear, a very hardy sort, which had 

 never before suffered. The previous mid- 

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