THE RELATION OF ICE AND SNOW COVER ON 



WINTER-FLOODED CRANBERRY BOGS 

 TO VINE INJURY FROM OXYGEN DEFICIENCY 



By H. F. Bergman' 



CONTENTS 



Page 



Forms of injury 4 



Conditions under which injury occurs 7 



Factors affecting the dissolved oxygen 



content of water 7 



Physical factors 7 



Biological factors 8 



The oxygen requirement of cranberry 

 vines under winter flooding con- 

 ditions 11 



The ability of cranberry vines to with- 

 stand oxygen deficiency 12 



Page 

 The course of the dissolved oxygen con- 

 tent of the water on a winter- 

 flooded bog 13 



The reduction of the dissolved oxygen 

 content of the water under ex- 

 perimental conditions 18 



Effect of oxygen deficiency on cran- 

 berry vines 18 



Present status of the problem 21 



Suggestions for preventing winter- 

 flooding injury 21 



Summary 23 



The practice of flooding cranberry bogs during the winter is well established, 

 and cranberry growers believe that in most years little or no harm results from 

 it. However, growers both in Massachusetts and in Wisconsin have long known 

 that cranberry vines may lose many or all of their leaves, and that sometimes 

 many terminal buds and considerable portions of the stems are dead after the 

 winter flood is taken off in the spring. The first record of injury of this kind is a 

 report by Franklin^ of severe injury on two bogs in 1916, following late holding 

 of a deep winter flood. 



Winter-flooding injury has occurred much more frequently and has been more 

 severe in Wisconsin than in Massachusetts. In Wisconsin it often has caused 

 great reductions in j'ield and sometimes even the loss of an entire crop. When 

 winter-flooding injury began to be noticed in Wisconsin is not known, but by 

 1928 or 1929 its seriousness was recognized and it was considered to be one of the 

 most important problems confronting Wisconsin growers. For this reason it was 

 decided to study the conditions under which the injury occurs and to find a means 

 of preventing it. 



The possibility that winter-flooding injury might be due to a lack of oxygen 

 in the water was suggested by the fact that this had been shown to be the cause 

 of injury to flower buds, flowers, and growing tips of vines in June flooding.^ 



Determinations of the dissolved oxygen in the water on a few winter-flooded 

 bogs in Massachusetts from 1929 to 1932, and on various marshes in Wisconsin 

 in 1930, showed on some of them very little or no oxygen in the water over a 

 period varying from a few days to two or three months in Massachusetts, and up 

 to four or five months in Wisconsin. Observations from 1930 to 1932 on the 

 bogs in Massachusetts, showed that winter- flooding injury occurred only on bogs 

 where there had been very little or no dissolved oxygen in the water over a con- 

 siderable length of time during the preceding winter-flooding period. 



The data obtained up to 1932, however, failed to show definitely the conditions 

 under which injury occurs. For this reason, and also because changes in the 

 winter-flooding practice in Wisconsin seemed to have reduced very greatly the 



^Senior Pathologist, Fruit and Vegetable Crops and Diseases, Bureau of Plant Industry, Soils 

 and Agricultural Engineering, Agricultural Research Administration, United States Department 

 of Agriculture, East Wareham, Mass. 



^Franklin, H. J. Mass. Agr. Expt. Sta. Bui. 180, p. 232, 1917. 



^Bergman, H. F. 32nd Ann. Rpt. Cape Cod Cranberry Growers' Assoc, for 1919-20. 1920, 



