What are Killing Frosts? 



315 



When they are newly opened, about 26° would be the point 

 of danger. When the petals are beginning to fall, 28° 

 above zero is cold enough to cause uneasiness. When the 

 petals are off, they can stand 30° above zero. When the 

 shucks (calyx - tubes) are 

 beginning to fall off, 32° 

 above zero is the danger- 

 point. The above figures 

 will serve as a guide to the 

 fruit-grower as showing 

 the proper time to hght 

 the fires in the orchard." 



Chandler finds that 

 "The killing temperature 

 of peach blossoms, when 

 the tree is just coming 

 into full bloom, under 

 Missouri conditions, seems 

 to vary from about 22°F. 

 to 25° or 26°F. After the 

 blossoms are old enough 

 that they are probably 

 pollinated, and from that time on until the peaches are 

 as large as 3^ inch in diameter, at least, they continue to 

 become more tender until they will withstand but very 

 few degrees below the freezing-point, the seeds of young 

 peaches killing at a higher temperature than other peach 

 tissue." 



In New Mexico, Garcia and Rigney secured somewhat 

 different results (Bull. No. 89) : 



"The data recorded at the New Mexico Station show that the 

 fruit-buds, particularly those of the peach, at their different stages 

 of development, — at least, in the experiment station orchard, — 



Fia. 122. Grape-shoots killed by 

 a freeze. 



