262 STATE HORTICULTURAL SOCIETY. 



after a heavy rain, the leaves fell rapidly, but were not all gone or all yellow 

 until about November 7, although there were a number of severe frosts. 



COLD WINTERS. 



The winter of 1880-'81 was unusually severe. On the Delaware and Chesa- 

 peake peninsula in January the temperature fell to 12° below zero F., a very 

 unusual occurrence. The fruit buds were nearly all destroyed. Many trees 

 were killed outright. Thousands more were badly injured and have not 

 recovered to this day. Many persons have attributed the recent alarming 

 increase of yellows to this severe winter. It has also been asserted that in 

 Xew Jersey and upper Delaware a corresponding increase of yellows followed 

 the severe winter of 1856-'57. In Berrien county, Michigan, the increase of 

 yellows was also ascribed to the severe winters of 187;i-'73 and 1874-'75. 



This theory appears more tangible than the preceding, because the effect 

 of hard freezes is very apparent in injured bark and discoloixd wood, and be- 

 cause dark heart wood is not infrequent in trees suffering from yellows. It 

 has been a favorite theory with many writers. They have insisted that yellows 

 is very strictly a disease of northern clmates, naturally unsuited to the peach, 

 the fact or supposed fact that the disease did not prevail in middle Delaware 

 or in the southern States being cited as ample proof of this. Dr. Emerson 

 and Mr. Hovey, in particular, cite the very part of Delaware now badly 

 affected as proof that a mild climate is a safeguard. 



It is probable that anything which reduces the vitality of a tree will render 

 it more susceptible to disease, and in this way severe winters may have exerted 

 an evil influence; but that any degree of cold, or any sudden change of 

 temperature, can of itself cause peach yellows is, I think, impossible. The 

 following reasons seem to be conclusive: 



(1) If peach yellows is due to severe freezes it ought not to have appeared 

 first in centers of cultivation, but rather on northern border regions, where 

 severe winters are of more frequent occurrence. The whole history of the 

 disease shows the reverse of this to be true. 



(2) On such an assumption, peach yellows ought not to appear at all in 

 mild southern climates, yet it has been present for a nimiber of years in 

 Georgia, on nearly the southern limit of the successful culture of the peach, 

 at least of the so-called " Persian " peaches, the only race yet grown to any 

 great extent in this country. In this connection it is also well to rt member 

 that the peach is not indigenous to a warm climate, as some writers have 

 taken for granted. It flourishes best in the middle latitudes of either hemi- 

 sphere, i. e., between the thirtieth and fortieth parallels, and only exception- 

 ally north or south of these boundaries. 



(3) During the winter of 1856-'57, at Grand Rapids, Mich., many peach 

 trees were killed to the ground or greatly injured. Since that date there 

 have also been freezes which much injured peach trees. Yellows, however, 

 did not appear until about 1883 and has never been very prevalent. In other 

 parts of the State, e. g., in Washtenaw county and Ionia county, peach trees 

 have suffered repeatedly from cold winters, being killed back more often than 

 not upon low grounds, yet I have never seen a single case of yellows result- 

 ing therefrom. At Spring Lake, near Grand Haven, a succession of severe 

 winters between ] 870 and 18b0 greatly injured peach trees and practically 

 put a stop to the planting of orchards, but yellows did not became prevalent 

 in consequence, aiid has never proved a serious evil. Nevertheless, in 



