WEATHER IN CRANBERRY CULTURE 35 



northwestern part of the Massachusetts cranberry-growing region, for these bogs 

 always lead those on the Cape in their early growth, ^^ and minimum bog tem- 

 peratures on cold nights^in April are lowest inland. 



On the night of April 28-29, 1910, from 10 to 75 per cent of the iruit buds on 

 exposed bogs throughout the Cape cranberry section were killed by frost, much 

 injury occurring in some cases even where the winter water had been let off 

 within a daj^ or two. No official records of minimum bog temperatures were 

 made, but the Wareham Courier reported a range of from 17° to 23*^. March 

 and April had been warm and the season was fully ten days ahead of normal 

 when the frost came. 



A severe freeze the night of April 22-23, 1919, seemed to do no harm on most 

 exposed bogs, but it killed over half of the Early Black fruit buds on a large bog 

 in Norton. It did not harm the Howes buds there. Minimum bog temperatures 

 ranged down to 17° F. at the cranberry observing stations that night. 



The night of April 28-29, 1934, most of the fruit buds were killed on many 

 bogs, mainly in the northwestern part of the cranberry district (Middleboro, 

 Lakeville, Rochester, Freetown, Assonet, and Foxboro). Minimum bog tem- 

 peratures at the observing stations ranged down to 15° F. Again much loss oc- 

 curred on some bogs from which the winter water had been let off within a day or 

 two. The spring temperatures before the frost were about normal. 



There was a considerable loss by frost, mostly on bogs in the northern part of 

 the cranberry region, in the night of April 22-23, 1941, the minimum bog tem- 

 peratures ranging down to 17° F. March and early April had been colder than 

 usual, but there were several very warm days just before this frost. 



These records show plainly that, when bog temperatures promise to fall below 

 20° F. during the last week in April, it is best to flood, especially in inland locations, 

 unless the previous weather has been fairly cool and the spring is late. 



The winter fruit buds usually will endure an air temperature of 25° F. till they 

 grow to a cross diameter of over 2 mm. Very rarely are they killed by frost on 

 bogs from which the winter water has been drained in late March or early April 

 before the brown winter color of the cranberry foliage turns noticeably greenish. 



From each of these buds grows out, by the stages shown in Figure 7, a con- 

 siderable stem bearing the flower buds and a leafy tip. If, as often happens, a 

 winter bud is only slightly or moderately hurt by frost, the stem grows out but 

 usually fails to develop a leafy tip and may lack one or more flower buds also 

 (Fig. 5). Cape Cod growers commonly call this growth an "umbrella." It is 

 doubtful if such injury is often important, for a good set of fruit usually results 

 even over an area where nearly all the fruiting branches are in this condition 

 (Fig. 6). It is well to remember this when water for frost flooding must be used 

 sparingly. 



When the winter fruit bud is completely killed, new shoots start out around it 

 and farther down the branch (Fig. 8). 



New cranberry growth is never hurt by an air temperature of 30° F., but 29° 

 often does considerable harm if it lasts long, while 28° for a short time sometimes 

 does no injury. 



Slightly harmful frosts cup the tip leaves of the new growth characteristically 

 toward each other (Fig. 9). The leafy tips are somewhat more frost-tender than 

 the blossom buds and blossoms, and the new growth is most easily hurt by frost 

 before the flower buds begin to turn down (Fig. 7, D, E, F," and G). 



Ferns, grape, and scrub-oak leaves have about the same frost endurance as the 

 new cranberry growth, and much harm to any of the former around an exposed 

 bog is goodevidence that the bog is hurt. 



l^Plant growth in general is much retarded on the Cape in the spring, probably because of the 

 influence of the sea, the water warming up much more slowly than the land. 



