PEAR BLIGHT IN ILLINOIS. 



2. There is a sort of locust that stings the branch, and causes a similar phenoinenon 

 sometimes. 



3. There is an insect that eats into the roots of any of the tender buds on the terminal 

 branches, and sometimes causes them to break, or blight and wither. 



4. There is an insect, probably the Scolytus pyri, that eats a ring around the terminal 

 branches, and causes their death above, on the apple, and sometimes runs down on the 

 pear, and apparently causes the death below the part injured. 



5. There is a blight on the pear, beginning on the parts exposed to the hot sun, and be- 

 fore this characterised as the sun-blight, sometimes also affecting a newly trimmed apple tree 



6. But there is also a worse form of blight than all these combined, which developed 

 here in the most fearful ravages of the pear tree, quince, and privet bush, last season, and 

 in some cases, affected the apple also. It is the real " Asiatic cholera" of pear trees; and 

 I believe has never before spread among us in this county till last season. We suppose 

 that we /enow, now?, what you and your correspondents really mean by " pear blight," 

 when you speak in your saddest and most despairing tones — and we have never fully 

 known before. But lest it should still be different from your forms of blight, I will try 

 to describe it; for it is evidently very different from all the forms of blight mentioned 

 above, in its origin and effects, and coincides only in the single fact, that the terminal 

 branches appear to the careless observer, (but to no others,) to be first affected— just as 

 in the other cases. 



This form of blight differs from all the forms produced by insects above described, in 

 the fact that it always begins in the trunk and larger branches, and never in the small 

 shoots of the tree: and it differs from what I described as the "sun-blight," in a former 

 number of the Horticulturist, (Sept. 1849,) in the fact that the poisonous blotch on the 

 limbs or trunk, is as likely to appear in cool, as in extremely hot weather; and as often 

 found where the sun never shines, as beneath the full stroke of its rays. 



Indeed, I am inclined to think it is the natural sequali, or terminatori, of that singular 

 leaf blight which I described in the same article, of Sept. 1849. 



The first fatal symptom that strikes the e)'e, as in the other cases of blight above nam- 

 ed, is the blackening and perisliing of the terminal leaves and branches. But by a careful 

 microscopic examination, a dead and putrid blotch, or spot of bark, will always, (in this 

 form of blight,) be found on the neck, trunk, or branches, of the tree below, which has 

 thrown its poison first upward, and killed the tender terminal shoots, and then it again 

 passes downward, and never stops till all the tissues are killed, at least down to the origi- 

 nal plague spot. 



This spot is most likely to be found at those points where the bark is changing from 

 smooth to rough — either at the collar near the ground, or in or near the crotches and bi- 

 furcations of limbs and shoots. This, and other facts, induced last July, the suspicion 

 that the cause must be either fungus or animalculse. And, after examining many hundred 

 pear trees in this town and county, most of which are entirely ruined, I set about endea- 

 voring to ascertain what was the cause. 



I first spent a week in a thorough personal examination of my trees, root and top, "with 

 spade, knife, and microscope, at hand. I found nothing, save that the seat, or apparent 

 origin of the disease, was as indicated above, and a confirmed belief that it was the work 

 of fungus, or extremely minute animalculje, invisible with a common microscope. I ac- 

 cordingly procured a solar microscope of great power, belonging to the college apparatus, 

 presence of Professors Adams and Bateman, cut a small bit of bark where 

 the insects were, (if an3Mvhere,) and placed it in the focus of the microscope 



