158 THE STRAWBERRY IN NORTH AMERICA 



effective ; most growers prefer to plant varieties that do 

 not need to be sprayed. 



Vigor is the prerequisite of productiveness; weak- 

 growing varieties of superior quality may satisfy a few 

 amateurs, but not commercial growers. There is con- 

 siderable difference in the ability of varieties to endure 

 drought, due partly to differences in the texture of the foli- 

 age, but mostly to the fact that the roots of some sorts 

 penetrate the ground more deeply than others. The Ari- 

 zona, for example, has a deeper root system than the 

 Jucunda. 



Productiveness is the most desirable quality in a com- 

 mercial variety. If a variety lacks this it is soon discarded, 

 even though it may be desirable otherwise. A heavy yield 

 depends not only upon the vigor of the plant and the num- 

 ber of fruit stalks, but also upon the average size of the 

 berries and the length of the picking season. Judged by 

 present standards, a variety that will not yield 100 to 300 

 bushels to the acre under ordinary field culture, and 300 

 to 500 bushels under intensive market garden culture, is 

 not worth keeping. Fifty years hence this standard may 

 be considered as low as it would have been thought high 

 half a century ago. The Trebla, one of the seedlings of 

 Albert F. Etter of Ettersburg, California, is reported to 

 have yielded at the rate of twenty tons to the acre, which 

 is over 40,000 quarts. 1 



In the North, hardiness must be considered. During 

 the winter of 1905-6 many of the strawberry fields of 

 Canada and northern United States were covered with ice 

 for a long period. Most of the 200 varieties on trial at 

 the Central Experiment Farm, Ottawa, Canada, were 

 destroyed, although they had been heavily mulched. 

 > Jour. Heredity, VI (July, 1915), p. 328. 



