334 FUNDAMENTALS OF FRUIT PRODUCTION 



be operative in determining hardiness and that though maturity is 



frequently very important, it is by no means to be considered the sole 



factor. 



Table 52. — Percentage of Blackberry Canes Killed in Successive Winters'^^ 



1890 1891 1892 



Agawam 30 



Early King 10 12 8 



Erie 20 20 80 



Minnewaski 8 5 



Snyder 10 



Wachusett, 20 10 



Western Triumph 30 8 3 



Wilson 20 5 40 



Injuries from Drought not Uncommon. — Any variety may be weak- 

 ened from drought or fungous diseases and suffer unduly the following 

 winter. It is well known that large amounts of moisture in the soil 

 induce winter killing and that accumulation of ice on the surface of 

 the soil has the same effect. The relation of winter drought to winter 

 killing is perhaps less appreciated. Some unpublished investigations 

 by Emerson in Nebraska on this matter are of great importance, 

 pointing as they do to the conclusion that "injury to raspberries 

 in that locality was apparently almost wholly a matter of winter 

 drying."" Canes coated with paraffin suffered no appreciable injury 

 while untreated canes on the same stools were killed to the ground or to 

 the snow line. Observing that when the snow cover was deep enough 

 to keep the soil from freezing the canes were not injured, even in the 

 parts that projected above the snow, Emerson tried to secure the same 

 results by mulching. Various mulches were tried and the ground was 

 in many cases kept from freezing but the canes were killed down to the 

 mulch. "Temperature readings taken at various depths in the mulch 

 indicated that for a period of some weeks a portion of the mulch was 

 continuously below the freezing point. Of course, the water absorbed by 

 the roots from the unfrozen ground could not pass through the frozen 

 part of the cane. Other studies suggested, though I perhaps did not 

 have sufficient data to prove it, that the canes are not frozen for any 

 length of time when surrounded by snow."^^ 



Card^'^ remarks that though in Nebraska covering of raspberries 

 and blackberries is necessary the same varieties are commonly grown in 

 New York without protection, despite the fact that the winters in 

 Nebraska are no colder. He reports that during one winter in Nebraska 

 when the mercury fell below zero (Fahrenheit) but once, with —5° as the 

 minimum, unprotected canes were killed. Plants in adjoining rows 

 exactly alike, except that they were laid down and covered, were entirely 

 uninjured. The following winter was much colder but the soil was moist 



