48 MASS. KXPERIMENT STATION BULLETIN i7H 



COOPERATIVE CRANBERRY INVESTIGATIONS 



Conducted by the Bureau of Plant Industry, United States Departmenc 



of Agriculture, in cooperation with the Massachusetts 



Agricultural Experiment Station 



H. F. Bergman, senior pathologist. Division of Fruit and Vegetable Crops 

 and Diseases, in Charge 



Oxygen Content of Winter Flooding Water in Relation to Injury to 

 Cranberry Vines. (H. F. Bergman.) Continuing studies made previous- 

 ly, measurements of the oxygen content of the winter flooding water on 

 several bogs were made at weekly intervals from January 22 to March 

 8, 1940. These bogs were flooded early in December and were under 

 ice from the middle of December 1939 until about March 10, 1940. The 

 oxygen content of the water on all bogs, from the time the first samples 

 were taken until the ice melted, was less than 1 cc. per liter and in some 

 instances was less than 0.5 cc. per liter. 



There was no crop on two bogs on which the water was held until 

 about the middle of May. On other bogs the water was withdrawn late 

 in March or early in April and the crop varied from about normal to 

 about one-half. From limited data available, it appears that vines which 

 had produced a large crop are more susceptible to oxygen deficiency 

 injury during the following winter flooding period than are vines which 

 had produced only a small crop, probably because the former have less 

 stored carbohydrates than the latter when placed under winter flood. 

 Vines with an ample carbohydrate reserve are able to withstand an oxygen 

 deficiency in the winter flooding water for a longer time than those with 

 a small supply of stored carbohydrates. One of the bogs on which the 

 oxygen content of the winter flooding water was determined showed no 

 oxygen deficiency injury. This bog had a very light crop in 1939. Two 

 other bogs which had moderately good crops (50-60 barrels per acre) in 

 1939 showed some oxygen deficiency injury. The injury was greater in 

 more deeply flooded areas on these bogs, which were probably also areas 

 of greater or more prolonged deficiency. The injury was manifest in the 

 retardation in the development of flowering uprights and of the flowers 

 themselves and in reduced fruit production, but there was very little leaf 

 drop. 



The fourth (State) bog showed the most severe oxygen deficiency in- 

 jury on an area which had produced a relatively heavy crop (75-80 bar- 

 rels per acre) in 1939. The injury caused a decided retardation in the 

 development of new uprights and of the flowers and a marked decrease 

 in yield, as well as much leaf drop in areas in which injury was most 

 severe. 



The reduction in yield was due mainly to the failure of flowers to set 

 fruit, but very dry weather during the late summer also contributed by 

 reducing the size of the berries. The number of flowers produced was 

 normal with an average of four to five per upright in each of the main 

 three varieties on the bog. Early Black, Howes, and McFarlin. The per- 

 centage of flowers setting fruit was as follows: Early Black, Section 5, 

 12.8; Early Black, Section 14, 15.5; Howes, Section 13, 10.2; McFarlin, 

 Section 13, 12.1. A normal set in these varieties would average 30 to 35. 

 percent. 



Studies are being continued on the relation between the amount of 



