8 MASS. EXPERIMENT STATION BULLETIN 433 



Summer Rainfall and Size of Massachusetts Cranberries 



It was shown in Bulletin 402 (pages 85-88) that there is a relation between the 

 amount of rainfall in August and the size of Massachusetts cranberries. Further 

 study with more data indicates that July rainfall is also involved. The correla- 

 tions between rainfall and cranberry size, as derived from Ta^le 9A, are as 

 follows: For July, +0.361+0.128; for August, -f 0.432 ±0.12; for July and 

 August, -{-0.554 +0.102. Evidently the berries require a lot of moisture through- 

 out the period in which they are growing. 



Distribution of the Berries Among the Vines 



Massachusetts cranberry crops vary greatly from year to year in this respect, 

 some being largely in the tops of the vines while others are well distributed among 

 them. As the following table shows, the distribution varies largely according to 

 the amount of rainfall in August, drouth in that month evidently being mainly 

 responsible for the "top-berry" condition by its more harmful effect on the de- 

 velopment of the under berries. The crop of 1936 may seem to be an exception; 

 but the rainfall was only 1.87 inches in July and .90 of an inch in the first half of 

 August that year. As the distribution of rainfall in July and August in 1937 was 

 much like that in 1936, it may be thought that the effect on the berry distribution 

 should have been the same; but the 1937 crop was ten days later than that of 

 1936 and evidently benefited from the rain later in August. 



Year Percentage of August 



Growers with Rainfall 



Crops Mainly (Inches)- 

 "Top" Berries' 



Year Percentage of August 



Growers with Rainfall 



Crops Mainly (Inches)' 

 "Top" Berries' 



"From October Growers' reports, provided by C. D. Stevens. 

 2From Table 12. 



It follows from the above that cranberry crops after dry Augusts are liable to 

 a higher percentage of injury from fall frosts than those following plenty of rain 

 in August. >" 



Snowfall and Cranberry Yields 



No evidence was found that the amount of snowfall at any time materially 

 affects the cranberry crop in any of the three States. This is not surprising, for 

 the duration and character of the snow cover should be as important as the 

 amount," and adequate information about this is lacking. 



l^Mass. Agr. Expt. Sta. Bui. 402, 1943, p. 36. 

 "ibid., p. 11. 



