5i6 



Bulletin 316 



for the different exposures, but there are none known to the writer that tend 

 to show the comparative value of the various exposures with respect 

 to injiiry from frost when the difference in date of blooming is considered. 

 It appears that a majority of fruit growers in this State consider the 

 northern exposure preferable, believing that the retarding of the date 

 of blooming, due to the lower temperatures of the northern slope, more 

 than compensates for the greater freedom from frost on the southern 

 slope. 



OCT5 



_> OCT 5 



Fig. 140. — Average dale of first killing frost in fall 



EFFECT OF SOIL AND SOIL COVERING ON FROST 



In investigating the conditions under which frost occurred in the cran- 

 berry districts of Wisconsin, the writer found that old cranberry bogs 

 covered with a thick carpet of dried vines were much more liable to frost 

 than were bogs more recently planted. It was believed that the thick 

 covering of vines prevented a large part of the heat received from the sun 

 during the daytime from reaching the soil, and, since but little heat was 

 stored up by day, only feeble resistance was offered to the fall of tempera- 

 ture at night. 



In the Cape Cod cranberry marshes it is the practice to spread about 

 half an inch of sand over the surface of the marshes each year, thus cover- 



