298 Missouri Agr. Exp. Sta. Research Bulletin No. 8 



even in a very dormant condition. Whipple^ describes a considera- 

 ble amount of killing he has observed in Montana. When apple 

 buds are killed it is not necessarily true that all parts of the buds are 

 killed; generally only the flower parts, so that the buds will open 

 in the spring into a whorl of leaves and for this reason the fact that 

 any killing occurred may not be observed. He found also that in 

 some cases not even all the flower parts were killed, but on opening, 

 various malformations were to be observed; thus in some the pistils 

 were entirely absent and in some both stamens and pistils. In some 

 cases seedless apples were developed from such flowers. 



Under Missouri conditions, especially in the Ozark region in 

 the thinner soil, we have observed a considerable amount of killing 

 by the freezes of December 9 and 29, 1909, when the temperature 

 went to -5 F. and -8 F. respectively. During the same year buds 

 of the York Imperial, as well as Jonathan, that had been largely 

 killed by the same freeze, were sent in from points in Illinois. In 

 most cases, however, the entire bud was killed. The Jonathan is 

 the one variety in which a considerable amount of such injury has 

 been observed. In low places where the cold air may settle and re- 

 sult in a very low temperature, all of the Jonathan buds were killed, 

 even on healthy trees. However, in the Missouri Experiment Sta- 

 tion orchard following a temperature of -20 F. on January 7, 1912 

 not a large percentage of the buds were killed. Of 200 Jonathan 

 buds counted, 38 per cent were found to have been killed, and of 

 the same number of Ben Davis buds counted, none were found dead. 

 Of course some buds in which the flower parts were injured may have 

 been overlooked. However, a good crop was secured in that year. 

 In this orchard the trees had been kept in a healthy condition, while 

 practically all the orchards observed, and all the orchards from which 

 twigs were sent, were neglected orchards where the trees had made a 

 weak growth the summer before and had set their fruit buds very 

 early, probably pushing them too far early in the season before this 

 freeze. 



Killing of Apple Bloom. Killing of the flowers is a common 

 form of injury to apples resulting from low temperatures, at least 

 under Missouri conditions. An effort was made to determine what 

 is approximately the killing temperature of the full bloom of apples. 

 The following table gives the results of freezings with apple, peach 

 and other fruits, just before the bloom opens, in full bloom, just after 

 the bloom falls, and when the fruit is as large as it has been when it 



'Montana Agr. Exp. Sta. Bui. 91, 1912. (Bibl. No. 113). 



