1919.] PUBLIC DOCUMENT — No. 31. 45a 



and the type of pruning designed for them may be again 

 applied. Most of the trees made an excellent growth, and 

 the effects of the different methods of pruning are beginning 

 to appear. 



The extreme cold of the winter of 1917-18 is without prece- 

 dent, and we may hope that it will not occur again for many 

 years. Lower minimum temperatures have occurred, but the 

 number of extremely cold days greatly exceeded that of any 

 other winter on record. The records of the meteorological 

 department show twenty-three days with a temperature of 

 zero or lower; of these, twelve were — 10° or lower and 

 4 were — 15° or lower, while the minimum of — 22.5° occurred 

 on both Dec. 30, 1917, and Feb. 2, 1918. Severe cold began 

 about December 10 and continued almost without interruption 

 until February 24. 



Such severe weather must cause great damage to the fruit 

 interests. The peach crop was practically all destroyed 

 throughout the State, and there was considerable injury to 

 the trees. Many Baldwin apple trees were killed outright 

 or severely injured, and there was more or less damage to 

 other varieties. As is always the case when there is general 

 winterkilling, there was great variation in the amount of 

 damage done. While the factors involved in winterkilling 

 are very complex, certain of them may be quite clearly seen. 



1. The Location of the Trees. — Those located on low 

 ground without free outlet for cold air, and w'ith extensive 

 hillsides or plateaus above offering conditions which favor 

 the cooling of the air, show more damage than trees located 

 where air drainage is good. 



2. The Variety. — Bakhvin, Gravenstein, King and Rhode 

 Island' Greening were among the varieties suffering most. 

 Oldenburg, Wealthy, Mcintosh, Yellow Transparent, Northern 

 Spy and Ben Davis are some of the varieties rarely injured. 



3. The Condition of the Tree. — Lack of vigor due to neglect, 

 poor soil conditions or the production of a heavy crop in the 

 season of 1917 rendered the tree more susceptible to injury. 

 Often in young orchards, trees of excessive vigor, which had 

 grown late in the fall and failed to ripen their wood, were, 

 badly damaged. 



