WEATHER IN RELATION TO CRANBERRY 

 PRODUCTION AND CONDITION 



(Supplement to Bulletin 433) 



By Henry J. Franklin, Research Professor in Charge, and 

 Chester E. Cross, Assistant Research Professor, Cranberry Station 



Weather studies have been continued at the Cranberry Station since Bulletin 

 433 was issued in 1946, and the results are presented here. The junior author 

 should be credited with the studies of cranberry size and cranberry production in 

 Massachusetts, while the senior author is responsible for the material on cran- 

 berry keeping and on production in New Jersey. 



Table 1 was prepared after careful inspection of a variety of weather data, 

 those items which seemed to have influenced cranberry keeping most being in- 

 cluded. There is some opinion that July and August rainfall may have an im- 

 portant effect on cranberry keeping quality, ^ but the evidence, except that re- 

 lating to drouth in conjunction with high temperatures and excessive sunlight 

 (see Footnote 5, Table 1), is no longer convincing. The figures in the summation 

 column (column 7), which are a reflection of those in columns 2 to 6, show a 

 marked and consistent relation to the keeping qualities shown in columns 8 and 

 9, except as related to the material in footnote 5, the large sums indicating good 

 keeping quality and the small ones poor quality. Judging by the material in the 

 table, there are two important and very different causes of poor condition in 

 cranberries as they come from the bogs, as follows: 



1. Development of Putrefactive Fungi. This is the more common and im- 

 portant of these causes, and it may be considerably controlled by proper bog 

 treatments. 2 The summations in Table 1 suggest that the general importance of 

 this factor may be determined with considerable confidence early enough in the 

 growing season to indicate reliably whether treatments are likely to pay. A 

 forecasting service in this connection probably should be undertaken presently. 

 Such a service might also be a helpful guide to a wise division of the crop for dis- 

 posal as fresh or processed fruit. 



The factors included in Table 1 seem to suggest that the susceptibility of 

 cranberry vines to fungus attack during the growing season is very largely 'de- 

 termined by the first of March, the main influence being the amount of sun- 

 shine the >ear before and, less importantly, in February. All this is probably 

 due to a sugar relation. On the other hand, the spring weather items shown in 

 the table seem related mainly to the early development of the fungi concerned 

 and appear to be of decreasing importance in the following order: Spring tem- 

 perature, spring rainfall, March sunshine. As the sunshine of March seems 

 significant here while that of April and May does not, and as the rainfall of 

 March seems to be rather more important than that of either April or May, it 

 appears that the weather of March leads that of any other single month in its 

 relation to the fungus infection of cranberries.^ Since most of the cranberry 



1 Mass. Agr. Expt. Sta. Bui. 402, pp. 73, 74, 76, 77, 1943; and Bui. 433, pp. 10, 23, 1946. 



2 Control of Cranberry Fruit Rots by Spraying. U. S. Dept. Agr. Cir. 723, 1945. 



^ The apparent tendency of high March temperatures to reduce production in the year in which 

 they occur (Bulletin 433, pp. 5, 13. 24) while the temperatures of April and May show no such 

 effect tends to confirm this. 



