62 MASS. EXPERIMENT STATION BULLETIN 402 



Wareham indicate that an advantage of three to five degrees is about all that can 

 be expected of them. Obviously, they can be helpful only on still nights with 

 fairly large temperature inversions, and their value then is reduced by the ad- 

 vantage that stillness affords (p. 45). They will never be used much on bogs in 

 the East. 



Blowers with heaters have never been successful anywhere, because the heated 

 air rises too rapidly. 



Cloth Screens 



Tobacco shade cloth has been tried considerably as protection from frost on 

 cranberry bogs.^^ it is not satisfactory when there is much moss under the vines. 

 Good secondhand cloth is so hard to get that its use is not feasible. One thickness 

 of new cloth is not enough. Two thicknesses spread on the vines are good pro- 

 tection for most Massachusetts bogs, and this seems the best way to use it, for 

 supports are too troublesome and costly. The cloth is too bulky to handle well 

 on large areas, but it may be left spread on a bog several days without reducing 

 the protection much. It is too expensive, but is more available for this use than 

 other kinds of cloth, and more practicable than glass, paper, lath, or other screens. 

 Its use requires too much tramping on the vines and is not advocated. 



Smoke 



The smoke from fires near bog margins is no help,^^ their heat alone giving 

 protection and that for but a short distance. 



Heaters 



Oil-burning hjaters, used widely to protect orchards from frost, have been well 

 tried on cranberry bogs and fields of other low-growing crops** and are effective 

 in raising temperatures there. Their use on cranberry bogs, however, is unwise 

 because of the expense involved, the risk of firing the vines, and the injury to the 

 vines from necessary tramping and from spilling of oil. Wood fires in ventilated 

 50-gallon oil drums, properly spaced over a bog, have been tried by Isaac Birch 

 at East Taunton and seem more feasible. 



Sprinkling Systems 



In 1931 a bog of two acres in Carver was equipped with a Skinner pipe system 

 (Fig. 12, upper) which has been in service ever since as protection from both 

 frost and drouth and has been very satisfactory. Like results are reported from 

 a bog in North Harwich, equipped more recently with a rotating-head system 

 (Fig. 12, lower). Such installations are costly^^ but their use by cranberry grow- 

 ers will increase. They may perhaps be made to provide winter protection by 

 covermg the vines with ice. The recent discovery of good insecticidal controls 

 for the cranberry fruit worm has improved the possibilities of dry bogs greatly, 

 and this urges sprinkling to reduce their other leading hazards. 



82Mass. Agr. Expt. Sta. Bui. 160, 1915, pp. 93-94; Bui. 168, 1916, p. 1; and Bui. 180, 1917. pp. 

 184-185. (Copies in the Middleboro library.) 



^^Schoonover, Brooks, and Walker, op. cit., p. 13. 



8*Mass. Agr. Expt. Sta., 25th .\nn. Rept., 1913, p. 5 (copy in the Middleboro Library); Smith, 

 J. Warren, Agricultural Meteorology, 1920, p. 26; U. S. Monthly Weather Rev. 53:351, 1925; 

 and 55:354-357, 1927 (copies in the Middleboro library); and Young, op. cit., pp. 34-35. 



^^The cost before tne war was $450 to $500 an acre where surface water could be used. It is a 

 big gamble to try to pump the water from the ground. 



