Source of Data : 



Young, Floyd D. Frost and the Prevention of Frost Damage, 

 U. S. D. A. Farmers' Eul. 1588, 19U0, 



Detailed information as to vfhat temperatures different varieties of apples 

 will stand at various stages of development are not available. Incomplete data 

 indicates that varieties of the Delicious group are less resistant to frost damage 

 than any of the other commercial varieties grwim in llassachusetts , Mcintosh, 

 Cortland, Early Mcintosh, Milton, and Melba appear to be quite resistant to damage 

 from spring frost as compared to varieties of the Delicious group. Late blooming 

 varieties such as Northern Spy and Rome Beauty appear to be resistant to spring 

 frost injury but hovf much their resistance is due to less advanced bud development 

 is not definitely known. 



Wind 



High \Yinds during bloom may desiccate the stigma and other flower parts. In 

 addition, winds may injure the flowers to such an extent as to destroy their capacity 

 of shedding pollen and setting fruit. Probably the most undesirable effect, however, 

 is that bee activity is reduced considerably on windy days. 



Humidity 



High relative humidity may retard the release of the pollen and thus reduce 

 the possibility of pollen transfer by insects. On the other hand, low humidity may 

 dry the stigmas and reduce pollen germination. However, humidity low enough to 

 affect fruit set would probably not occur under tessachusetts conditions. 



Rainfall 



Continous rainfall during bloom retards the release of pollen, inhibits bee 

 flight and thereby reduces fruit set. HovTever, intermittent rainfall with periods 

 of sunshine during bloom ordinarily does not adversely affect a commercial set, 

 with favorable weather and plenty of bees only a relatively short time is necessary 

 for adequate cross pollination. In trees with a "snow ball" bloom it takes only 

 one blossom setting fruit in 20 for a commercial crop assuming five blossoms to a 

 spur. 



Water 



Although a deficiency of v/ater may reduce fruit set, in some plant species. 

 It would seldom be a limiting factor in this aspect vjith tree fruit in Massachusetts. 

 However, in some years probably tree growth may be significantly reduced because of 

 drought and thereby have an adverse influence on subsequent crops, 



— IK J. Lord 

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