88 MASS. EXPERIMENT STATION BULLETIN 402 



Summary and Conclusions 



The only relations between weather and cranberry size that seem from thi s 

 study to be important are shown in the correlations of Tables 1 and 2, and are 

 the following. 



L Sunshine of December and January. A high correlation was found between 

 this factor and size of berries, from the data of both Griffith and Stevens. It 

 appears from this material that the chances are 7 to 1 that Massachusetts cran- 

 berries will be large when there have been over 300 hours of sunshine in Decem- 

 ber and January, and are 9 to 1 that they will be small when there have been less 

 than 270 hours of sunshine in those months. This seems to support strongly the 

 findings of Bergman given in this bulletin and to be especially significant as it • 

 has to do with a period when the cranberry bogs are mostly under ice-covered 

 water and sunshine is at its yearly minimum in duration and intensity. The 

 correlations of Table 1 suggest that this sunlight relation may be more important 

 with the Early Black than with the Howes variety. There is a hint here that 

 ice-sanding cranberry bogs early in the winter may tend to stunt the berries (pp. 

 11 and 28). 



2. Mean Temperature of March. There was a high correlation between the 

 temperature of March and cranberry size, the apparent chances being 7 to 1 that 

 cranberries will be large after a March mean temperature above 38° at Middle- 

 boro, and 8 to 1 that they will be small after this temperature has been below 34°. 

 March is normally the month in which the ice disappears from the winter flood 

 of the cranberry bogs in southeastern Massachusetts, and the time of its leaving 

 depends on the prevailing temperatures. It appears from these correlations that 

 the earlier the ice is melted the larger the cranberries are likely to be. 



3. August Rainfall. A considerable correlation was found between August 

 rainfall and cranberry size, and Table 2 suggests that the rainfall of September 

 may also be a factor. The results of experiments reported heretofore^ support 

 the evidence from these rainfall correlations. 



The various correlations suggest that the winter and spring weather elements 

 considered affect cranberry size fully as much as does rainfall, within the usual 

 limits, during the growing season. No clear evidence was found of any relation 

 between June or July rainfall and cranberry size. As good size is an important 

 quality in cranberry marketing, It is probably often advisable to irrigate to ob- 

 tain It; but It does not appear from these studies that material advantage is 

 likely to be gained by doing this before the berries are set and well started in 

 growth. This seems to fall in with the common grower experience. 



CRANBERRY SIZE AND KEEPING QUALITY 



The available evidence indicates that crops of cranberries of much greater 

 than average size seldom keep well. The crops of 1922, 1925, 1931, 1933, and 

 1942 were of definitely larger berries than those of the other years since 1917, 

 and all of those crops except that of 1925 were outstandingly poor in keeping 

 quality. The summer of 1925 was very dry throughout, the mean temperature 

 during the cranberry storage season was abnormally low, and the berries went 

 to market promptly in response to a brisk demand. 



<Mass. Agr. Expt. Sta. Bui. 271:250, 1931. 



