WEATHER IN CRANBERRY CULTURE 75 



simple summation of "day degrees" above a minimum of 50° F.; that is, in com- 

 puting the figures, 50 is subtracted from the mean temperature of each day and 

 the remainders are added together. Fifty was chosen as a zero point because 

 many important cranberry fungi begin active growth at about this temperature, 



A study of the table shows that in 1912, 1914, 1919, 1922,1929, 1930, 1931, and 

 1933, all years in which the Early Blacks showed an unusual amount of decay, 

 the temperature for May and June was unusually high. In all cases the summa- 

 tion was above 600. Moreover, these were the only years in which this variety 

 is known to have shown an unusual amount of deca}^ On the other hand, in 

 those years when the temperature for May and June was lower, the keeping qual- 

 it\^ of the Early Blacks was much better. 



High temperatures during September and early October are well known to 

 favor the decay of cranberries in storage. In 1913, 1917, 1918, and 1926, all good 

 years for Early Blacks, the September temperatures were cool; whereas in 1915 

 and 1921, with very high temperatures in September but favorable conditions m 

 May and June, the condition of the Blacks was reported as only fair. 



In all the years in which the keeping quality of the Early Blacks was poor, 

 namely, 1912, 1914, 1919, 1922, 1929, 1930, 1931, and 1933, the Howes also 

 showed poor keeping quality. In addition, the Howes were relatively inferior to 

 the Early Blacks in 1915 and 1926 and somewhat inferior in 1927. The reason 

 for this is not entirely clear, but it seems possible that high temperatures in July 

 and August are usually necessary for satisfactory development of Howes cran- 

 berries. At least, in all the years except one in which the summations for July 

 and August fell below 1100, the Howes were either poor or decidedly inferior to 

 the Early Blacks, that is, in 1912, 1914, 1915, 1926, 1927, 1929 and 1930. It 

 must be admitted, however, that in general the keeping quality of the Howes 

 corresponds less definitely with temperature conditions during the growing season 

 than does the keeping quality of the Early Blacks. This is not surprising in view 

 of the fact that the Howes are kept much later than are the Early Blacks. 



Size of Crop in Relation to Keeping Quality 



One of the first correlations which appeared when the present study was under- 

 taken was an apparent relation both in Massachusetts and in New Jersey between 

 exceptionally large crops and unusually poor keeping quality. At the time it 

 seemed possible that the size of the crop might influence the estimates of the keep- 

 ing quality, as some part of a large crop is usually held a longer time in storage. 

 Since 1926, however, the keeping quality of the crop has been measured with some 

 degree of accuracy by means of test lots held in storage, and it is apparent that 

 the keeping quality of the exceptionally large (460,000 barrel) crop of 1931 fell 

 much below what might have been expected as compared with crops of the pre- 

 vious years. The only other crop of equal size, 1914, was the poorest prior to 

 1930. The very best crops, those of 1920 and 1928, have been relatively small — 

 both less than 355,000 barrels. 



On the basis of the observations summarized above, the worst possible combina- 

 tion of circumstances from the standpoint of keeping quality would be high tem- 

 perature in May and June, a greater than normal number of days having .01 

 inch or more of rain in both July and August, and an unusually large crop. This 

 combination of factors has occurred twice in the last twenty-five years — in 1914 

 and in 1931 — years which will long be remembered by those interested in cran- 

 berries in Massachusetts because of the poor keeping quality of the fruit. 



