46 MASS. EXPERIMENT STATION BULLETIN 347 



Oxygen Content of Flooding Water in Relation to Injury to Cranberry Vines. 



(H. F. Bergman and W. E. Truran.) Measurements of the oxygen content of 

 the water and of the light intensity at different depths were made on several bogs 

 which were flooded during late May and early June for insect control. The 

 minimum light intensity necessary to maintain the oxygen content of the water 

 at a level high enough to prevent injury to the buds depends upon a number of 

 interacting factors which vary from bog to bog. On one bog flooded to a depth of 

 12-16 inches the oxygen content of the water, at 22° C, increased as long as the 

 light intensity at a depth of 12 inches did not fall below 12 percent of the full 

 midday intensity. When the light dropped below 12 percent the oxygen content 

 also decreased. The oxygen content of the water on all bogs examined was suffi- 

 ciently high to prevent bud injury. 



Spraying Experiments. (H. F. Bergman and W. E. Truran.) Preliminary 

 experiments on the control of rose-bloom of cranberry showed that this disease 

 may easily be checked by sprays. Although no spraying was done until the rose- 

 bloom had developed fully, one application of 5-2-50 Bordeaux with rosin fish-oil 

 soap as a spreader and sticker, applied at the rate of about 300 gallons per acre, 

 greatly reduced the infection and two applications entirely eliminated it. 



In spraying experiments for the control of fruit rots, Z-0, a copper fungicide 

 of unknown composition, in concentrations of 1-50 or 13^-50, and Cupro K, a 

 form of copper oxychloride, 13^-50, applied at the rate of 250-300 gallons per 

 acre, gave much poorer control of rots than did Bordeaux 5-2-50 applied at the 

 same rate. Bordeaux 5-2-50 with rosin fish-oil soap reduced the amount of rot 

 to one-third to one-half of that of the check plots. Copper hydro 40 at concentra- 

 tions of 4-50 or 5-50, applied at the rate of 250-300 gallons per acre, compared 

 favorably with Bordeaux in the reduction of rot. On some plots it reduced the rot 

 more than Bordeaux. On other plots on another part of the same bog Bordeaux 

 gave the better control. A copper oxide spray made up with Cuprocide 1^-50, 

 bentonite 2^^-50, or Cuprocide 2-50, bentonite 3^-50, applied at the rate of 

 250-300 gallons per acre, brought about a greater reduction in rot than did 

 Bordeaux 5-2-50 applied at the same rate. 



As Bordeaux with soap does not give a uniform spray deposit on leaves and 

 fruits of the cranberry, various adjuvants in different proportions were added to 

 the Bordeaux to determine whether better spread and adhesiveness could be ob- 

 tained and the effectiveness of the spray thereby increased. Bordeaux 5-2-50 was 

 used in all tests. To 50 gallons of this was added one of the following materials or 

 combinations: Penetrol 1 quart; Areskap }/2, 1,2, 4, 8, and 16 ounces, respectively; 

 Santomerse 2 and 10 ounces, respectively; bentonite 2J^ pounds; bentonite 2J^ 

 pounds with 1 pound of rosin fish-oil soap; bentonite 2i/^ pounds with Areskap 

 1, 2, and 8 ounces, respectively; bentonite 23/^ pounds with Aresket 4 ounces 

 (Areskap, Aresket, and Santomerse are sodium salts of sulfonated diphenyl 

 compounds). Determinations of copper in the spray residues on leaves were made 

 within 1 to 2 days after the vines were sprayed and again shortly before the 

 berries were picked. None of the materials used increased the amount of copper 

 in the spray residue beyond that in the residue of Bordeaux made up with rosin 

 fish-oil soap, although somewhat better distribution of the spray coating was 

 obtained when 4-8 ounces of Areskap were added to 50 gallons of the spray than 

 with the Bordeaux to which rosin fish-oil soap was added. On plots on which 

 poor control of rots was obtained, it was found that the copper content of the 

 spray residue was very low. Otherwise there was no evident relation between the 

 amount of copper in the spray residue and the degree of rot control. 



Blueberry Disease Investigations. (H. F. Bergman.) A blighting of flower 

 clusters and new leafy shoots of blueberry caused by Sclerolinia was worse in 



