WEATHER IN CRANBERRY CULTURE 91 



It seems from the temperature summations in Table 3 that the chances are 

 5 to 1 that Early Black cranberries will ripen early when the sum of the mean 

 temperatures of the spring months at Middleboro is more than 141, and are 8 to 

 1 that they will ripen late when this sum is less than 133. One may see here that 

 the very dangerous situation that attended the occurrence of the great frosts of 

 early September 1917 was well established by the end of May of that year; for 

 cranberries were then bound to be late in ripening and therefore very susceptible 

 to injury by early-fall frost, and the likelihood of such frosts was clearly indicated 

 b> previous temperatures^ and the prevalence of sunspots (pp. 55, 56 and 57). 



There are some errors hard to avoid in the material in Table 3. The date of 

 first full-car shipment fails in some years (e. g., 1919, 1922, and 1933) to index 

 correctly the time of ripening because unfavorable weather delayed the picking 

 of the berries. In a few years (e. g., 1916, 1923, 1930, and 1939), the mean tem- 

 peratures at Middleboro may have failed to be representative of those in the 

 whole cranberry-growing section. The growers became frightened by the very 

 large crop of 1914 and shipped berries earlier than they otherwise would have; 

 but in some > ears, when they were sure of the market because the crop was small 

 (e. g., 1918, 1921, 1924, 1927, and 1938), they delayed picking a little to give the 

 berries better color and size. However, the correlations shown would be stronger 

 if these known sources of error were removed from the table. 



To sum up, then, cranberries ripen early if the spring has been warm and 

 August is cool, and ripen late after a cold spring and warm August. 



LATE RIPENING AND KEEPING QUALITY 



There seems to be no certain record of a Massachusetts cranberry crop that 

 ripened late (say, with the first full-car of Early Blacks shipped after September 

 9) and had poor keeping quality^ except that of the Howes variety in 1926; and 

 this exception was probably due largely to difficulties in marketing the largest 

 cranberry crop the country had ever produced. 



'The mean temperature of the calendar year 1916 was subnormal in both northern and southern 



New England. 



*As already noted, the 1922 crop was not a true exception to this. 



