- 5 - 

 Estimated percentage of the length of raspberry canes killed during the winter 



[bl 154 '55 '56 '57 '58 '59 '60 '61 



In order to get some idea of the response of the various raspberry varieties 

 to cold, each spring after the buds start, an estimate is made of the percentage 

 of cane length which is dead. This is done before the canes are cut back. No 

 attempt is made to isolate canes killed by spur blight. Since the ends of the 

 canes are cut back to 4 to 5 feet as standard pruning practice, the reduction in 

 yield is not so severe as the amount of dead terminal would suggest. With a weak 

 growing variety 10 per cent of the cane length might be removed without affecting 

 yield whereas with a vigorous variety it might be as much as 25 to 30 per cent. 



The table gives the results of these estimates made over a ten year period 

 for the varieties which are recommended for Massachusetts. 



The figures for 1958-59, a winter of about average temperatures, and those 

 of 1960-61, a very cold winter, can be compared with those of 1959-60, a very 

 warm, open winter. Comparing the '60 and '61 estimates, there was more injury in 

 the warm winter of '59- '60 in every case. Comparing the '59 and '60 figures, 

 only two varieties, Muskoka and Sodus appear to have suffered worse in the 

 average winter than in the warm one. However, a 10 per cent difference in estimate 

 is probably too small to be significant. 



Judging from the reaction to our winters, Gatineau and Early Red appear 

 worthy of further trial. Gatineau has behaved well in five out of eight winters 

 and Early Red five out of seven. September hasn't survived the winters so well 

 but because it produces a fall crop on the terminals of the new canes, production 

 is not cut as much as the amount of injury suggests. Madawaska has consistently 

 come through various types of winters in good shape. Taylor is only fair in cold 

 resistance, its usefulness is limited more by susceptibility to virus. While 

 Muskoka has come through only four of seven winters in reasonably good shape, its 

 behavior under the conditions of 1959-60 (which severely injured most other 

 varieties) indicates that it is well worth further trial. It is worth noting 

 that Latliam, which is usually pretty winter hardy, was severely injured in the 

 1959-60 winter. Milton produces high quality fruit but is a bit too subject to 

 winter injury for commercial use except in very favorable locations. The winter 

 injury to the canes of Durham need cause no concern because they are cut to the 



