28 MASS. EXPERIMENT STATION BULLETIN 402 



generally falls down evenly and satisfactorily among the cranberry vines from the 

 ice before and as it melts. At times, however, when thick ice breaks up, especially 

 where the flowage is deep, floating cakes carry the sand around a good deal, 

 depositing it unevenly. The sand also sometimes tips the ice cakes and so gets 

 dumped in heaps. It is better, therefore, not to sand on the ice late in the winter. 

 Ice sanding very often reduces the following cranberry crop as much as sanding 

 directly on the vines. Bergman, in this bulletin, discusses the relations of the 

 flowage ice to oxygen deficiency in the water under it, and the cranberry injuries 

 due to the latter. The probably harmful effect of sand on or in the ice under some 

 conditions is not the only valid objection to ice sanding as it is commonly done. 

 Growers use much more sand on the ice than they would spread directly on the 

 vines and so build up the sand bed of their bogs faster than they should. Bogs 

 may be sanded about as cheaply in other ways as on the ice, except where the sand 

 has to be trucked to them. Ice sanding is advisable under special conditions, but 

 is valued too highly as a general practice in this State. (See pp. 11 and 88.) 



HAIL DAMAGE 



In frequent years hailstorms partly or wholly destroy the crop on a very few 

 cranberry bogs in Massachusetts. They come fully as often in the New Jersey 

 cranberry area and more than twice as often on the Wisconsin bogs.^ They hardly 

 ever do material harm on bogs on the Pacific coast. 



Massachusetts 



Because of the weak convection over the sea, summer hailstorms are much less 

 prevalent in Barnstable, Nantucket, and Dukes counties than in Plymouth 

 County and other parts of the cranberry district. Only one, that of June 15, 

 1921, seems to have occurred on Nantucket since 1886,* and they are rather rare 

 on the outer Cape. As will be seen by the lists of the more destructive of these 

 storms, given below, the town of Wareham and its vicinage (Map 1) has a much 

 worse record of damage by hail than any other cranberry area anywhere. This 

 is due partly to the many excellent and extensive bogs in this area and prob- 

 ably partly to peculiarities in the locale.' All the great hailstorms in this region 

 listed here came with the same condition, a cold front that passed in the daytime 

 and was between a warm west or southwest wind on one side and a cool north- 

 west or north wind on the other. In every case, the center of low pressure in the 

 morning was over or near the Maritime Provinces, the general trend of the isobars 

 to the west of the center was from north to south, and the cold front lay from 

 northeast to southwest or east-northeast to west-southwest across central New 

 England. The general aspect of the weather maps was like that for cold waves 

 in winter, only the pressure and temperature gradients were less steep. It appears, 

 therefore, that for severe hailstorms in the main cranberry district there must be 



^Atlas of American Agriculture, section on precipitation and humidity, p. 44, fig. 80, 1922. 



^The only hailstorm remembered to have done considerable harm on Nantucket came on May 

 18,1877, at about 10 o'clock at night. It affected nearly all parts of the island, stripped the trees 

 of their foliage and blossoms, broke four to five thousand panes of glass, and killed large numbers 

 of crows and blackbirds. The hailstones ranged in size from that of a walnut to that of a hen's egg. 



^Buzzard's Bay with its converging shores heads at Wareham. As winds pass over the sea more 

 easily than over land because of less surface friction, this bay provides an excellent channel for the 

 delivery of strong, moist west and southwest winds into the Wareham region. Such winds are 

 thrown upward somewhat in coming ashore and, being lighter, override the cold wind from the 

 north under the hail conditions here considered and so may strengthen the convection and favor 

 the occurrence of hail. Records seem to show a similar special tendency of severe hailstorms to 

 occur around the head of Narragansett Bay. 



