WEATHER AND CRANBERRY PRODUCTION 5 



The correlations found worthy of notice in this study, together with conclu- 

 sions drawn from them, follow. The differences in the weather relations of the 

 cranberry crops of the different areas studied are surprisingly great. 



Sunlight 



It must be said that no fully satisfying sunshine records that cover long terms 

 of years and may properly be used in cranberry-production correlations exist 

 anywhere. It has been necessary to use records made at centers outside the 

 cranberry-growing districts, and these are of value only as they may show the 

 general sky conditions that prevailed over the cranberry areas themselves. It is 

 only fair to note that no important correlations were found between the cranberry 

 crop and the sunshine records made at the Blue Hill Observatory and at Provi- 

 dence. 



No evidence was found that variation in the amount of sunlight is considerably 

 related to cranberry production in New Jersey. Reduced sunlight evidently is 

 seldom a limiting factor in that State, probably because of the more direct rays 

 of the sun there. Correlations in Tables 4, 5, 6, and 18 and Figure 2 show the sun- 

 light relations found in Massachusetts data.^ The Boston records seem to show 

 that the amount of sunlight in the year before that of the crop has an important 

 effect on the size of the crop and on the size and keeping quality of the berries. 

 This probably comes about through the build-up of the vines in starch and sugars. 

 It appears to be one of the major influences that determine the amount and charac- 

 ter of Massachusetts cranberry crops. This may be due partly to limiting effects 

 of the frequent and persistent fogs that occur along the Massachusetts coast. 



Table 4 shows also the relation found between sunshine in the year before the 

 year of the crop and cranberry production in Wisconsin. The correlation co- 

 efficient suggests that this relation, as compared with that in Massachusetts, 

 is a modest one; but it is probably more important than it seems, for it appears 

 in the face of temperature influences so powerful that they dwarf the effects of 

 all other elements except winterkill and frost. Adequate data on the size of the 

 berries and the keeping quality of Wisconsin cranberry crops, whereby possible 

 effects of sunshine might be determined, are not available anywhere. 



It was hard to determine the proper limits of the sunshine period that should 

 be used in the above studies. The sunshine at Boston from Apr^l to September, 

 inclusive, of the year before that of the crop shows exactly the same degree of 

 correlation as that of the whole year, and the latter seems quite satisfactory for 

 practical purposes, especially when it is summed and published in tabular form 

 in comparison with that of other years as it has been heretofore in the Annual 

 Meteorological Summary for Boston published by the Weather Bureau. 



No relation was found between the amount of sunshine in any part of the crop 

 year and the size or quality of the crop in either Massachusetts or Wisconsin. 



Temperature 



The studies disclosed no important variation in New Jersey cranberry crops 

 due to temperatures. 



Table 7 and Figures 3, 4, and 5 show the temperatures found to affect cran- 

 berry production in Massachusetts, the higher temperatures being somewhat 

 destructive in all cases. Material in Table 6 suggests that the harmful effect 

 of high temperatures in March may be partly pathological. It may be related 

 also to unrecognized frost injury in April. It should be noted that the March 



%ee also Mass. Agr. Expt. Sta. Bui. 402, 1943, pp. 85-88. 



