40 MASS. EXPERIMENT STATION BULLETIN 339 



COOPERATIVE CRANBERRY INVESTIGATIONS 



Conducted by the Bureau of Plant Industry, United States Department 



of Agriculture, in cooperation with the Massachusetts Agricultural 



Experiment Station 



H. F. Bergman, Senior Pathologist, U.S.D.A., in Charge 



Development of Strains of Cranberry Resistant to False Blossom. 



(H. F. Bergman and W. E. Truran.) Reciprocal crosses have been made be- 

 tween Early Black and each of the four varieties, Centennial, McFarlin, 

 Paradise Meadow, and Shaw's Success; and between Shaw's Success and Cen- 

 tennial, McFarlin, and Paradise Meadow. In addition to these, crosses of 

 McFarlin x Aviator, Paradise Meadow x Aviator, and Shaw's Success x Aviator 

 were made also. From 30 to 60 percent of the flowers pollinated in the various 

 combinations set fruit. Seeds from these crosses will be planted during January 

 and February. 



Seedlings from crosses made in 1934 were set out on the bog during the past 

 summer. Although the season was very hot and dry very few of the seedlings 

 were lost. 



Investigations on the Effect of Copper on the Growth of Cranberry 

 Vines. (H. F. Bergman and W. E. Truran.) Vines which had been sprayed 

 twice in 1935 with Bordeaux mixture came through the winter flood in much 

 better condition than those not sprayed. Only a small percentage of dead 

 terminal buds and uprights were found on vines that had been sprayed, while 

 on unsprayed vines 30 to 40 percent of the terminal buds and also many entire 

 uprights were dead. The leaves of sprayed vines were much greener than those 

 of unsprayed vines. By measurement of the chlorophyll content it was found 

 at the middle of May, a month or more after the winter flood had been with- 

 drawn, that the leaves of sprayed vines had 20 percent more chlorophyll per 

 unit of leaves than those of unsprayed vines. This difference decreased as the 

 season advanced and by the middle of June was no longer evident. 



Three to four weeks after the second application of Bordeaux spray it was 

 observed that the sprayed vines were a more intense green than the unsprayed. 

 Measurements of the chlorophyll content of leaves from a sprayed and an un- 

 sprayed plot on the State Bog about the middle of August showed that the 

 sprayed leaves had about 15 percent more chlorophyll per unit weight of leaves 

 than the unsprayed ones. The chlorophyll content of cranberry leaves, under 

 usual bog conditions, begins to decrease early in August. In the leaves from 

 sprayed plots no decrease was evident at the middle of August. The darker 

 green color of leaves of sprayed vines was evident up to the time that the berries 

 were picked early in September. 



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

 These experiments included tests of combined fungicide-insecticide mixtures 

 of sulfur spray and of copper oxide dusts. For comparison certain plots of each 

 series were sprayed with either 4-1-50 or 5-2-50 Bordeaux mixture with soap. 

 Two applications only of sprays or dusts were made except on one bog where 

 some plots were sprayed three times. Determinations of the amount of copper 

 in the spray deposit on leaves were made at intervals during the summer, the 

 last about two weeks before the berries were harvested. 



Better control of fruit rots was secured with Bordeaux than with the other 

 sprays or dusts. Bordeaux 5-2-50 did not give better control of rots than 



