EXPERIMENTAL WORK WITH CRANBERRIES. 39 



sprinkling systems at present on the market are even more expensive, 

 and will probably, on this account, never be practically available for this 

 purpose. 



As indicated in last year's report, the expense connected with the use 

 of orchard heaters is prohibitive, to say nothing of the danger from fire, 

 and of the injurj^ to the vines which would unavoidably be done by the 

 spilling of oil. 



There are many other possible methods of frost protection for cranberry 

 bogs which have not j^et been tried. It may be possible to cause the frost 

 to be drawai out slowly from the vines after a frost by screening the bog 

 from the sun during the first two or three hours of the morning, perhaps by 

 a curtain of smoke. This method is suggested by the well-known fact 

 that the greater part of the injury, caused by freezing in both plant and 

 animal tissues, is usually due more to the sudden withdrawal of the frost 

 in the process of thawing than to the formation of the frost in them. 



The possibiUty of protecting a bog from frost by covering it over with 

 cloth is of course generally recognized. Though this would be an ex- 

 pensive protection, it has the probable advantage of being entirely effective. 

 It is, however, probablj'^ unwise to attempt any special frost protection 

 on diy bogs because of the pecuUar conditions and difficulties otherwise 

 associated with such bogs. The onl}'' kind of bogs, the general conditions 

 of which probably warrant special protection, are those which are winter- 

 flowed but cannot be reflowed to any extent. 



As a rule, the managers and owners of most of the Cape bogs, which 

 have poor frost protection, seem to have overlooked the method of pro- 

 tection, which, though not perfect, is, nevertheless, many times very- 

 effective, and which can be applied with a relatively small cost, namely, 

 that of keeping the bog well sanded. It has been shown by the experiments 

 carried out by Prof. H. J. Cox for the United States Weather Bureau and 

 by the Wisconsin Station that there is a protection against several degrees 

 of frost to be had by this use of sand. Many of the Cape growers have 

 come to realize this from general experience, and strikmg examples of the 

 efficiency of this protection are not infrequently seen. It seems certain 

 that a very considerable percentage of the Cape cranberry losses from 

 fro.st, incurred where water protection is not available, could be saved 

 by a more general understanding and application of this principle of re- 

 sanding for protection. 



3. FUNGOUS DISEASES. 



The arrangement by which this work has heretofore been carried on in 

 co-operation with the Bureau of Plant Industry of the United States 

 Department of Agriculture has been continued this year. Dr. Shear has 

 had general supervision of the spraying experiments as heretofore and 

 has conducted the laboratory'- investigations. A considerable number of 

 spra5'ing tests were carried on by the growers, especially in Wareham 

 and in and about Harwich, the results of some of which have not as vet 



