V^EATHER AND CRANBERRY PRODUCTION 9 



Monthly temperatures of the year before the crop year show no significant 

 relation to the size of the crop. 



Table 5. — Temperature at Middleboro, Plymouth, and Hvannis and 

 Massachusetts Cranberry Production. 



(Correlation coefificient and probable error.) 



March and July '- .3767 ± .0826 



March, July, and September — .4415 ± .0775 



March, July, Septtmber, and October - .4818 ± .0739 



March, May (+), July, September, and October - .5140 + .0708 



July and September - .4629 ± .0756 



July, September, and October — — .4953 + .0726 



May (+), July, and September - .5521 + .0669 



May (+), July, September, and October - .5717 + .0648 



Precipitation and the Size of Massachusetts Cranberry Crops 



Working within the crop year, Franklini^ has indicated a significant correlation 

 between the rainfall of March and April and the size of the crop. His figures 

 also show that 2 to 4 inches of rain monthly in May, June, July, and August help 

 to produce a large crop, but that more than 4 inches or less than 2 inches in these 

 months is detrimental. 



Because very scanty or very abundant precipitation appears to be detrimental 

 while a moderate amount is beneficial, the type of correlation used in this paper 

 cannot well be applied in studying the relation of rainfall to Massachusetts 

 production^ However, the correlations were calculated for the twenty-one 

 months preceding the crop, and only one coefficient stands out enough to be 

 considered here. 



The rainfall coefficient for October of the year preceding the crop is +.2968 

 ±.0836, indicating that rainfall in this month is very important to the crop of 

 the coming year. The probable reasons for this dependence upon water are 

 given in the discussion of October sunshine following Table 3. 



Table 6 brings together those weather items which now seem to have the most 

 influence on cranberry production in Massachusetts. They are: 



1. Sunshine the jear before the crop year. (Table 6; also Table 4 and Figure 

 2 in Bulletin 433.) 



2. Rainfall the year before the crop year. Rainfall in July seems to be 

 especially important, its lack being favorable to the crop of the following year 

 (Table 6) and its abundance unfavorable. i* While drouth in the growing season 

 (May to August, inclusive) clearly tends to reduce the crop of the year in which 

 it occurs (Mass. Agr. Expt. Sta. Bui. 271, p. 250, 1931; and Bui. 433, fig. 13) r 

 drouth, whether it comes in the growing season or in the fall, seems to be related 

 to conditions considerably favorable to the crop of the following year. 



3. Rainfall in the growing season of the crop year, this being most important 

 in July. (Bulletin 433, pages 14 and 15.) 



4. February sunshine (Table 6). Since recording of sunshine was begun in 

 Boston, there have been thirteen years in which February sunshine was less than 

 150 hours; and the Massachusetts cranberry crop has been small to moderate 

 in all of them. 



^3 Mass. Agr. Expt. Sta. Bui. 433. 1946. 



'■^ The table shows six years in which the July rainfall was over five inches, and the cranberry 

 crop was small to moderate in all of them and also in all of those next after them. 



