FIRE BLIGHT IN PEAR TREES. 



329 



The most prominent and generally re- 

 ceived of these theories are, first, " The 

 Insect Blight ;" second, " The Fiozen Sap 

 Blight:' 



The first was brought to notice by the 

 Hon. John Lowell, of Boston, in 1836, by 

 the supposed discovery of the mischievous 

 insect. {Fruits and Fruit Trees of Ameri- 

 ca, page 322.) The second by yourself, 

 (Ibid, page 324,) Rev. H. W. Beecher, and 

 others. 



To the first of these views, a ready assent 

 was yielded, out of respect to the high 

 source from which it emanated. It thus 

 for a time became the popular doctrine. 

 On more mature reflection and observa- 

 tion, it is, however, evident that the " Sco- 

 lytus pyri:^ which he saw on the diseased 

 limbs of the trees, were attracted there by 

 the existence of the disease, and were not 

 its cause. This idea ih, therefore, mostly 

 abandoned, and the second, " The Wrozen 

 Sap Blight" theory, adopted. This, to a 

 limited extent, explains the evil fully. But 

 it is by no means the principal agent in the 

 work of destruction. Its appearances are 

 so very fully described in your Book of 

 Fruits, page 324, that it is unnecessary to 

 repeat it here. 



There never was a more favorable year 

 to test its correctness — one which forebode 

 more destruction to the Pear tree, than the 

 last. It will be remembered that the latter 

 part of the summer of last year (1846) was 

 peculiar for its continued invigorating show- 

 ers, which set vegetation in active motion 

 after it had almost come to a stand by a 

 previous drouth. Moisture and growth 

 continued until late in the fall, when it was 

 suddenly brought to a check by freezing 

 weather, so severe that the tops of the 

 young Peach trees in the nursery were fro- 

 zen, and many Cherry trees altogether de- 

 stroyed. This was also the case with ccr- 

 voL. 11. 42 



tain kinds of Pears in the nursery, as, for ex- 

 ample, the Washington and the Blood good ; 

 of these I had each a row of fine stout 

 trees, rebudded high on other sorts, and 

 which had made fine growth and good 

 heads. The bodies of these were almost 

 ail frozen to the ground, without seeming 

 to have affected the tops, in most of them. 

 While other sorts, such as the Columbia, 

 Golden Beurre of Bilbao, Bartlett, dec, 

 similarly treated and situated, alongside of 

 the former, were unharmed. And yet 

 there has been less Blight this summer than 

 for many years. I have lost but one tree, 

 with the exception of those above referred 

 to, this summer, and that was from the ef- 

 fects of a previous year's injury, with 

 which it still struggled. 



On the supposition that the frost theory be 

 the theory, how shall we account for its ab- 

 sence, under such favorable circumstances 

 for its operation ? There is no doubt that 

 when late luxuriant growth, with the sap 

 vessels full and extended, and an immature 

 wood, is overtaken in this condition, by sud- 

 den freezing, it will have the effect of 

 bursting the sap vessels and destroying the 

 vitality of the immature wood ; the effect of 

 which may either be instant death to the 

 whole tree, or mortality in part, just in pro- 

 portion to its maturity and ability to resist 

 the frost. And this w'ill fully explain why 

 its destructive effects are sometimes carried 

 into the next summer. And, indeed, that 

 at times, by a powerful effort of vegetation, 

 it succeeds in apparently overcoming the 

 mischief and throwing it off, still, however, 

 leaving the tree an impaired constitution, 

 with which to struggle out a brief exist- 

 ence. 



It seems to me, then, we must look to a 

 different agent as the cause, for what may 

 be with us properly called the " J^ire 

 Blight:* This I apprehend we shall find 



