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Des Moines; Leavenworth, April i, 1872. 



MASK UILLEB, Managing Editor and Fnlilislier, Dee Moines, Iowa. 

 Dr. J. Stayman, Dr. Wm. M. Howsley, Dr. S. H. Kridelbaugh, 



Corresponding F.ditor, Loa^enworlh, KausaB. 



AsEooUta Editor, Leaveawortb, KaDR&s. 



Entomological Editor, ClariDda, Iowa. 



The Pear and Its CaItnre.~ConcIoded. 



By The Couresponding Editor. 



Having thus spoken at considerable length of e.Ktreme changes in temperature being the 

 exciting cause of blight in the early part of the season, say May and June, we will now 

 speak of blight, produced at a different time and by a different cause. We mean by this 

 what is usually, but incorrectly, called insect blight. We choose to call it sunscald blight, or 

 that which is produced b}' the direct rays of the sun. 



While the blight first spoken of does not manifest itself usually, till May or .Jnne, this 

 latter, or sun-scald blight, is not seen till July or August. Intense heat can have no par- 

 ticular agency in the first kind spoken of, because the rays of the sun have not, in May or 

 June, acquired sufficient force to produce anything more than ordinary growth. While 

 in the latter kind of blight, at the time it occurs, there can be no such sudden and extreme 

 changes of temperature as produce the first, but is brought on by long continued and 

 intense heat of the sun generally. 



We had a striking instance of sun-scald blight in the summer of 1870. The new made 

 wood on many trees, which seemed to have nearly recovered from the earlier blight, 

 were killed in July and August. This result could not be looked upon as very strange, 

 when we remember that the mercury, during nearly the whole month of July, and a part 

 of August, ranged from 97° to 103°, the sky scarcely ever obscured by clouds. 



If then, the first kind of blight is produced by the freezing of the sap, so as to rupture 

 the cells by its expansion into crystals. So, also, is the second or sun-scald blight, pro- 

 duced by the direct rays of the sun, destroying the vitality of the sap. In the one kind it 

 is produced by the intense abstraction of the heat, and in the other by the intense and 

 direct infusion of heat — so that in both cases it is the result of atmospheric influences. 



A striking illustration of this sun-scald blight is found in the following facts: First, it 

 is known to all who were living in Kansas during the summer of 1860, that it was drier 

 and hotter than had ever before been known. The adjacent inhabitants of Missouri and 

 the Indians, who had been here since about 1830 — a period of about thirty years — had 

 never known it either so dry or hot. It is also known that the ninth day of July and the 

 second day of August, 1860, were more intensely hot than any other days of the season, 

 the mercury running up to 112° in the shade, with a sirocco wind each day, blowing 

 almost a gale. 



NOW FOR THE RESULTS UPON VEGETATION. 



We had a field of corn planted on the seventh day of June, which, notwithstanding the 

 drought, was growing thriftily, and which, if we remember rightly, had not yet shown a 

 tassel. The blades on this field of .corn were killed outright from the tip, half way back 

 to the stock. They looked as if they had been dipped in boiling water, all the green col- 

 oring matter in them having enlirelj' disappeared. 



