The Blight in Pear Trees. 435 



the leaves and spray to the roots of the tree. This injury oc- 

 curs either in autumn or in the spring, and, perhaps, at both 

 periods. The general effect is, most probably, produced in 

 the spring, for it is found that those localities, where the 

 fruit usually escapes destruction by spring frosts, are meas- 

 urably exempt from fire blight. The Detroit River and the 

 Niagara are instances of this. 



As a means of avoiding this evil, it is of great importance 

 to graft only on hardy stocks, of a tried kind. I have lost 

 two trees, where the injury was in the stock only, and below 

 the graft. It is also desirable to have the graft near to the 

 ground, so that the entire trunk may be of the kind sought. 

 A very moderate protection to the trunk will preserve it from 

 injury, such as a hay-band enveloping its whole length, a 

 mat drawn loosely round it, or even a single fold of coarse 

 cotton. If the trunk be saved, even should the limbs perish, 

 a new head will soon be formed, to supply the place of the 

 one destroyed. Mr. Downing tells us that he has arrested the 

 progress of blight, by cutting off the limbs and burning them. 

 His supposition is, that he thus destroyed the insects con- 

 tained in the limb, and prevented further depredations. I 

 have seen trees that were never lopped at all, when the limbs 

 had been blighted, and the blight has equally ceased and dis- 

 appeared from the neighborhood, so that the burning and the 

 non-burning seem to have the same effect. The ready and 

 obvious explanation is, that the blight disappeared because it 

 it is not a thing of annual recurrence, but only happens in 

 peculiar seasons, which experience proves may occur only at 

 long intervals. 



I feel great confidence, Mr. Editor, that there is no such 

 thing as insect blight in pear trees, and we may, therefore, 

 drop the distinction of frozen sap blight, and come back to 

 the old name of fire blight, which was given from the appear- 

 ance of the effect produced, and does not mislead us. I sub- 

 mit, again, to your consideration, that the true point of in- 

 quiry is, to learn how the invasion of cold acts upon the 

 tree, so as to produce that local engorgement of sap which 

 speedily ferments and then dries away, and leaving a dead 

 girdle round the trunk or limb, and, of course, killing the top 

 above it. 



Urbana, August 24, 1849. 



