BULLETIN 231] 



WALNUT CULTURE IN CALIFORNIA. 



341 



TABLE I. 

 Showing average daily hours of sunlight for periods of five days. 



1907 March had 3 days with 1 hour or less of daily sunshine. 

 March had 7 days with 2 hours or less of daily sunshine. 

 April had 6 days with 1 hour or less of daily sunshine. 

 April had 15 days with 6 hours or less of daily sunshine. 

 May had 2 days with 1 hour or less of daily sunshine. 

 May had 9 days with 6 hours or less of daily sunshine. 



1908 March had 1 day with 1 hour or less of daily sunshine. 

 March had 3 days with 2 hours or less of daily sunshine. 

 April had day with 1 hour or less of daily sunshine. 

 April had 2 days with 2 hours or less of daily sunshine. 

 April had 2 days with 6 hours or less of daily sunshine. 

 May had day with 1 hour or less of daily sunshine. 

 May had 2 days with 6 hours or less of daily sunshine. 



Average amount of possible daily hours of sunshine in California 

 for March is about 12 hours ; for April, 13.5 hours ; for May, 14 hours. 

 For April, 1907, there was 52 per cent of the possible amount of sun- 

 shine ; for April, 1908, there was 78 per cent ; for May, 1907, there was 

 65 per cent of the possible amount of sunshine; for May, 1908, there 

 was 74 per cent of the total number of hours. 



Non-blighting of Late Blooming Trees. As previously stated in the 

 comparison of the two seasons, the season that opened late, that is 1908, 

 had almost no walnut blight. What was true of the majority of bear- 

 ing trees during that season is always true of trees that bloom late. The 

 majority of the bearing orchards of California are at this time seedling 

 trees, differing greatly in their blooming periods. The difference in 

 time is frequently from one to two months and may be as much as three 

 months between the earliest and the latest French varieties. Such a 

 wide range in time of blooming gives considerable chance for difference 

 in climatic conditions. We find that the early or medium blooming 

 trees are in blossom at a favorable period for the blight to develop 

 while the late bloomers come into flower at a time when bacteriosis can 

 make little headway. Particular attention has been given to this 

 phase of our investigation in the hope of finding a commercially profit- 

 able tree that blooms at a season when conditions for the infection of 

 the small nuts is at a minimum. While this work is not yet completed 



