Killing of Plant Tissue by Low Temperature 303 



that evaporation affects the killing of buds unless it be indirectly 

 by the drying out of the twigs. Cherry buds are more tender than 

 apple buds when exposed to sudden freezes like that at Columbia, 

 Missouri, January 7, 1912. They are also more tender when frozen 

 in the laboratory under conditions such that buds with the scales 

 removed kill no worse than normal buds. Evaporation could cer- 

 tainly play no part there. The buds at the ends of peach twigs are 

 generally more tender than those near the base of the twigs or on 

 spurs along the branches, but buds on the ends of twigs down in the 

 tree are as tender as any. It is probable that the buds that Goff 

 found more hardy toward the center of the tree were formed earlier 

 in summer and were more mature when the freeze came. 



One of the most promising means of avoiding loss from low 

 temperatures is by orchard heating, burning oil, coal or other material. 

 In some sections this practice is followed profitably, and it is recom- 

 mended in others. This subject is being studied at the Missouri 

 Experiment Station by Dr. W. L. Howard. In the work here re- 

 ported, no data has been gathered that is of value in a study of or- 

 chard heating, unless the results with freezing bloom and young 

 fruit may be of some value in determining the temperature at which 

 heaters should be lighted. Data on the killing temperature of the 

 bloom of fruit to be protected is very essential in orchard heating, 

 otherwise the heaters will too often be lighted and large expense 

 incurred when it is unnecessary, or perhaps sometimes they may not 

 be lighted when it is necessary, and loss will be incurred. A study 

 of orchard heating, like a study of the value of whitewashing as a 

 means of preventing killing from cold, should be carried on through 

 a large number of years since heating involves an expense certainly 

 not less than an average of $10 or $12 per acre a year, besides a large 

 initial investment, and the mere fact that the crop can be saved by 

 heating is no positive indication that in a period of twelve or fifteen 

 years enough crops will be saved, in spite of accidents inherent in 

 the method of healing, to pay for the cost of heating. 



ACKNOWLEDGEMENTS 



This work was begun under the direction of Dr. J. C. Whitten 

 of the Department of Horticulture of the Missouri Agricultural Exper- 

 iment Station, and advice has been received from him throughout 

 the work. Advice has also been received from Professor \V. L. 

 Howard of the Department of Horticulture, Professors B. M. Duggar, 

 C. Stuart Gager, and G. M. Reed of the Department of Botany; 



