PROTECTING ORCHARDS AGAINST FROSTS. 275 



by a cluster of blossoms. The apple buds are not influenced 

 by a little warm sunshine like the buds of the peach, and con- 

 sequently they do not begin growing until after there has 

 been considerable warm weather. 



We find the peach buds opening in central Missouri in a 

 normal year along about the 24th of March, while the apple 

 will be about two or three weeks later. Apple buds require a 

 l)igh temperature before they begin to grow appreciably. 

 Peach buds, on the other hand, particularly in late spring, 

 are apt to respond to a single day of warm sunshine by mak- 

 ing some growth. 



Because the apple blossoms come out one to three weeks 

 later than peach buds open, they are much less apt to be in 

 danger from frost. Under Missouri conditions orchard heat- 

 ing will be needed for the peach crop far more often than the 

 apple. There are seasons, however, as was the case in 1907, 

 and again in 1908, when frosts and even freezes came early 

 in Mnj, when all the orchard fruits, including apples, were 

 so far advanced that they were practically all destroyed by 

 the low temperature. 



If the fruit grower has both peaches and apples it will be 

 necessary to provide heaters for both the orchards. While 

 the peaches may require protection a week, tw^o weeks, or 

 three weeks, and in some cases as much as four weeks before 

 the apples are in danger they will need to be protected again 

 later on, if the temperature is sufficiently low to endanger 

 the apples. 



When the apple buds have grown sufficiently for the petals 

 to begin to show, they can stand a lower temperature than it 

 is popularly supposed. At this time they could possibly with- 

 stand from 10 to 13 degrees of freezing. From this stage on- 

 ward their resistance to cold becomes less and less as growth 

 progi'esses. When the petals are well emerged but have not 

 opened up they could stand from 4 to 6 degrees of freezing, 

 and as soon as they are open but not yet fertilized there would 

 be gTeat danger of injury if the temperature fell as low as 2 



