330 



FIRE BLIGHT IN PEAR TREES. 



ia the rays of the sun, as hinted at by 

 CoxE, in his book on Fruits. All observa- 

 tion and experience goes to show that the 

 month of June is the period of the year most 

 prolific in the Blight. The reason of this 

 is very obvious. It is the period when vege- 

 tation is in its most rapid and luxuriant 

 growth. It is then, Avhen nature seems 

 fairly to have aroused from its slumbers, 

 and to be in the full career of growth, that 

 this growth is most tender and susceptible 

 of injury. It is too, at this time, that the 

 sun, as ascending to its meridian power, 

 sends forth, between the showers, its strong- 

 est and most powerful rays. These are 

 brought to bear with all their force, not 

 unfrequently aided by the shower — drops 

 of water suspended in the tree, forming so 

 many lenses to operate on the sap in the 

 tender branches, the effect of which is to 

 scald the sap, burst their vessels, and pro- 

 duce precisely the same results that a 

 scorching fire would, if applied to the limb. 

 This, of course, produces instant death on 

 that part of the branch or tree where the 

 rays are brought to bear, and, of necessity, 

 all above that point ; and it will as certain- 

 ly carry death below with the returning 

 vitiated sap, (if the affected part be of con- 

 siderable size) if this is not immediately 

 amputated below the injury, or to where 

 the vitiated sap has extended in its down- 

 ward course. 



It may be asked, if the sun theory be true, 

 How is it that there has been so little 

 Blight the past summer ? This is owing to 

 two causes ; the first, no doubt, from a re- 

 duced material to operate on, previous sum- 

 mers having destroyed many of those most 

 easily affected. I presume it is in vege- 

 table as in animal life, some systems are 

 more susceptible to the attacks of certain 

 diseases than others. When death has 

 removed all the former, although the cause 



may continue to exist, it becomes inopera- 

 tive for the want of material. 



But the principal reason is, the remark- 

 ably and uniformly cool and mild state of 

 the weather during the whole of the sum- 

 mer. The rays of the sun being much 

 less powerful than is usual in this climate. 

 This fact alone is sufScient to prove the 

 agency of the sun in producing the Fire 

 Blight. I have not at my command a re- 

 cord of the temperature of the last three 

 or four summers, so destructive to the Pear 

 tree, but I will venture to assert that it will 

 be found, on examination, when this stood 

 highest the Fire Blight prevailed most. I 

 mean, of course, in the early part of sum- 

 mer, when vegetation is most active. It is 

 true, the Fire Blight prevails more or less 

 all over our country. It is also true that it 

 decreases as we advance n^rth, until it is 

 scarcely known. I am credibly informed 

 that along our northern border, especially 

 in the neighborhood of Detroit, there are 

 Pear trees as old as the first settlement of 

 the country, of a hundred years planting or 

 more. I have myself seen in northern dis- 

 tricts, large collections of Pear trees where 

 its ravages had never been felt. When we 

 look at the immense collections of this fine 

 fruit about Boston and Salem, the extent 

 of their varieties, the success with which 

 they are fruited, and continue to flourish in 

 the highest perfection, we cannot but feel 

 that the same cause or causes do not ex- 

 ist there for the destruction of this tree. 

 There are some sorts introduced into our 

 region which are constantly cut off by this 

 destroyer. Out of more than two hundred 

 sorts that I have imported and grafted on 

 standards, within the last fifteen years, I 

 have not succeeded in fruiting more than 

 thirty or forty, and can not now number 

 over one hundred sorts of this first grafting. 

 The following query may here also arise 



