CRANBERRY GROWING 



21 



frozen all day, usually about December 1 on the Cape. The water should 

 be held just deep enough to cover the vines. It is often best to let the 

 highest parts stick out when a bog is much out of level. The vines are 

 as well protected frozen into tiie ice as any way, though sometimes they are 

 pulled badly if they are not well anchored and if the ice is thick and is 

 lifted by water. Heavy ice sometimes does some harm by breaking off 

 the vines where it cracks; this injury appears in the spring as though a 

 cleaver had severed the vines and cut into the ground beneath them. 



If the bog can be refiowed, the winter water should be let off about 

 April 1 two years out of three. It may be held till May 23 the other 

 yearsio to control the fruit worm and false armyworm, reduce weeds and 

 fungous diseases and promote vine growth. It must not be held so late 

 if it is deep over much of the area or the vines are over vigorous. It may 

 be held till about May 20 rather regularly on bogs that cannot be re- 

 flowed. Holding after May 25 invites cutworm infestation. Algal scum 

 often develops in the flood water when it is held late. This sometimes 

 dries to form paper over the vines after the water is let ofif and is then 

 harmful (Fig. 18). It can be prevented from forming by dissolving 4 

 pounds of copper sulfate to the acre-foot in the flowage about the first 

 of April. Coarse crystals of the chemical in a burlap sack may be towed 

 in the water behind a canoe. Changing the fl-^.od water early in April, 

 exposing the bog to air a week or more, also usually prevents this trouble. 



Fig. IS. Cranberry Bog Cov 



from Algal Scum. 



Bogs used to ])L' fldoded regularly early in June to check insect pests. 

 This is advisable one year in three but is a dubious annual practice for 

 it carries fungous infection to the new growth, promotes fireworm infesta- 

 tion, and sometimes reduces the crop serioush- by drowning the flower 



'" It probably is better to let the winter flowage off early in April, reflood about A|>ril 25, 

 and hold the water till May 23, than to hold the winter water late. This serves all the 

 purposes of late holding, airs the \'ines, and gives time to work on the bog. 



