A REVIEW OF OPINIONS ON PEAR TREE BLIGHT. 



461 



ers during the hottest period of the day, is 

 injurious to the sap, as it rises to the most 

 succulent parts of the limbs, and to the ex- 

 posed surface of the bark of the cherry or 

 plum." 



Now it seems to us very evident that if 

 the electric fluid, was the cause of the dis- 

 ease, it would act in the first place iipon the 

 leaves, they being the most delicate and 

 exposed organs, and the extremities would 

 invariably manifest the injury sooner than 

 the " trunk or the thickest part of the 

 limbs." There is no reason, certainly, why 

 it should affect different kinds of fruit in 

 different parts, in the manner supposed ; 

 and this " agent," we should presume, 

 would be more likely to produce its effects 

 upon tall trees than those of lesser growth. 

 " A highly rarified atmosphere" would be 

 most detrimental, where its circulation is 

 less free, or more pent in by vegetation, and 

 the trunks of those having short bodies, and 

 limbs spreading more horizontally, would 

 be as liable to suffer, as those having a 

 more erect growth. If the facts are correct- 

 ly stated, they are to be ascribed to a more 

 consistent cause. Some vegetable fluids, 

 extracted from the fruit or the plant, or ex- 

 isting in them in a state of partial decay, 

 undergo fermentation, but nothing similar 

 takes place with the sap of a healthy tree, 

 and though the fermentation may be great- 

 er, when the air is charged with electric mat- 

 ters, there is no connection between the ef- 

 fect, and that which is produced in the sap 

 of a tree when attacked by disease. The 

 premises would not warrant the conclusions. 

 The circumstance related as to the change 

 in the appearance of a " fine St. Germain," 

 which occurred under the eye of the observ- 

 er, and to his great surprise, furnishes no 

 evidence that the attack of the disease was 

 so sudden, and its effects so decisive as he 



supposed. Indeed, the statement as to col- 

 or, shows that the tree had been diseased 

 for some time previously. He saw the 

 leaves change from " a dingy yellow to a 

 dark brown !" " A dingy yellow" is not 

 the color of the leaves of a healthy tree, 

 and when they present that appearance in 

 mid-summer, it is generally the precursor 

 of speedy decay. Those who have observed 

 the fire blight only at that stage when, 

 though the tree may have previously 

 had, upon slight examination, the appear- 

 ance of health, the fruit and leaves begin 

 to perish, might well suppose that it had 

 but just commenced its attacks, whilst 

 in fact, it had existed for months, and was 

 manifesting its final and fatal effects. " A 

 shower falling upon any plant, when the 

 sun shines fiercely," is frequently injurious, 

 and produces a more decided and sudden 

 change in the foliage of ihat which is dis- 

 eased than of the healthy. 



Thacher mentions, in his Orchardist, 

 that Mr. Cooper, of New- Jersey, discovered 

 that iron hoops hung upon the branches of 

 his trees, invariably preserved them from 

 blight. This remedy is somewhat singular, 

 and its success would seem to require some 

 additional confirmation, though so great is 

 said to be the benefit derived by pear trees 

 from iron, that we are prepared to hear that 

 it will produce any result desirable ; but if 

 electricity is the cause which produces the 

 disease, it would be difiicult to explain in 

 what manner that material should preserve 

 the tree from harm, Avhich most attracts it. 



It is true, we believe, that the disease is 

 less destructive to native varieties than to 

 those of foreign origin ; and such being the 

 case, we should endeavor to take some ad- 

 vantage of it. Native pears are generally 

 accidental seedlings, mature their wood 

 comparatively early, and are hardy ; the fo- 



