WEATHER IN CRANBERRY CULTURE 69 



growers at Christmas time. On the other hand, large shipments of the 1923 crop 

 of EarK- Blacks were made as late as the first two weeks in Nov-ember and con- 

 siderable shipments of Howes as late as the last week in February and the first 

 week in March. In general, however, it appears that trade practices indicate 

 October 15 and November 15 as fair approximations of "critical" dates for Early 

 Blacks on the one hand and Howes and odd varieties on the other, and that the 

 average condition of Early Blacks on October 15 and of Howes on November 15 

 would give a fairly satisfactory picture of the state of that particular crop for 

 commercial purposes. 



The Storage Period for the Different Varieties 



The actual demands made by commercial practice on the different varieties 

 are quite different. The Early Black variety generally begins to ripen by the first 

 week in September and as a rule is picked as soon as practicable. The picking 

 of the Howes variety usually begins about three weeks later. The picking, stor- 

 age, and transit period for Early Blacks, then, extends from the first week in 

 September to the middle of October; and for the bulk of the Howes, from Sep- 

 tember 20 to late November. 



While the storage period for Early Blacks is shorter than for the late varieties, 

 it is also much warmer and the significance of this difference in temperature is 

 not always appreciated. In attempting to compare the temperatures to which 

 cranberries are usually subjected in handling and storage in Massachusetts, the 

 daily normal temperatures at Boston, as given in Bulletin R of the U. S. Weather 

 Bureau, were used.^ These range from a daily mean temperature of 64° F. the 

 first week in September to 40° the third week in November. First, taking 32° 

 as zero, a simple summation of mean daily temperatures from September 8 to 

 October 15 was made as representing the "day degrees" to which the bulk of the 

 crop of Early Blacks is subjected; the total is 1029. A similar summation was 

 made from October 1 to November 20 as representing the "day degrees" to which 

 the Howes are ordinarily subjected; this total is 861. Of course, temperatures for 

 Boston do not exactly represent those on Cape Cod, but the results would be 

 about the same if weather records for any other eastern Massachusetts station 

 were used. 



A simple summation of mean temperature is, of course, not a thoroughly satis- 

 factory way of representing the amount of heat to which an organism is subjected, 

 and various attempts have been made to develop more satisfactory indexes. It 

 is a well-known principle that many chemical reactions double or somewhat more 

 than double with each rise of 18° F. in temperature. Professor Morse^ has shown, 

 moreover, that the rate of respiration of cranberries as measured by the amount 

 of carbon dioxide given off follows this rule very closely within climatic tempera- 

 tures. The rate of growth of most of the fungi which cause cranberry rots shows 

 a similar relation to temperature. 



Using a table of temperature coefficients prepared some years ago by the Liv- 

 ingstons^, in which 40° F. is considered as unity and the coefficient doubles with 

 each rise of 18 degrees, an "index" for the normal temperatures at Boston for 

 these same periods was computed. The index for September 8 to October 15, 

 inclusive, is 88.54, and for the period October 1 to November 20, inclusive, is 

 72.53. 



^Bigelow, Frank H. The daily normal temperature and the daily normal precipitation of tha 

 United States. U. S. Weather Bureau Bulletin R, 1908. 



^Morse, F. W., and Jones, C. P. Studies of cranberries during storage. Mass. Agr. Expt. Sta. 

 Bui. 198:75-87, 1920. 



^Livingston, B. E., and Livingston, Grace J. Temperature coefficients in plant geography and 

 climatology. Bot. Gaz. 56 (No. 5): 1913. 



