8 MASS. EXPERIMENT STATION BULLETIN 447 



turbine pumps are used (Fig. 5), and they vary greatly in efficiency. Repair 

 service is an important item to be considered as well as efficiency. The pumping 

 plants in use range in lift from 1 to 24 feet, averaging nearly 6 feet. Their horse 

 power a\erages about 30 and their capacity probably about 6000 gallons a 

 minute. A pump delivering 10,000 gallons a minute will flood 14 acres in 10 

 hours if the bog is not over a foot out of level. 



Stop-waters in bog ditches often help greatly in efficient use of limited water 

 supplies in frost flooding. 



The bog should not be shut in by high uplands and woods, for open locations 

 are less frost}'. 



Fig. 6. Cranberry Root Systems. 

 The plant to the left came from poorly drained, that to the right from well-drained land. 



The Form and Size of the Bog 



Other things being equal, small bogs pay better than large ones. Long narrow- 

 bogs, after a certain size is reached, are more profitable than compact ones. 

 The care of large compact bogs and the harvesting of their crops are dispropor- 

 tionately costly, because it takes more time to wheel sand to the center of the 

 bog and to bring the berries from the center; also, most of the bog operations 

 call for more tramping over, and consequent injury to, the vines on large blocky 

 areas. Another factor limiting the success of large bogs is the greater prevalence 

 of the black-headed fire-worm on them. Flooding favors this insect by destroy- 

 ing a fungus that often attacks it severely and by killing or driving from the bog 

 most of its enemies, such as spiders and parasites, at the same time protecting its 

 eggs from the adversities of winter. The natural foes of the pest take longer to 

 reach the center of a large compact bog again in effective numbers than to reach 

 the center of a small one. If, however, a large bog is long and narrow, none of 

 the factors mentioned are unfavorable. 



