Killing of Plant Tissue by Low Temperature 257 



their growth through the drought, and be just starting into their 

 normal dormant period when the wet weather began. They would, 

 not therefore, be so easily pushed into new growth as if they had 

 passed through a drying out period. At least observation indicates 

 that the weak tree which ceases growth early in the season is most 

 readily pushed into spring-like growth in autumn. 



It is probably also true that the young tree would offer less 

 resistance to the movement of sap upward in spring. It would thus 

 be able to secure sufficient water supply to prevent drying out until 

 a new layer of sapwood is formed. The old tree would have a greater 

 leaf surface to evaporate moisture and would offer more resistance 

 to the movement of sap. It would, therefore, seem possible that the 

 young tree might recover from the freeze better, though its injury 

 had been greater than that of the older tree. 



In the peach orchards on the Horticultural grounds and at 

 Brandsville and other points in South Missouri, following the severe 

 winter of 1904-05 and again following the severe winter of 1911-12, 

 the trees in a healthy, vigorous condition withstood the low tempera- 

 ture better than trees in a weak condition of growth. At Brands- 

 ville and other extreme southern Missouri points, following the 

 freeze of 1911-12, recovery was much more satisfactory from trees 

 that had been fertilized with nitrate of soda than with trees that 

 had not been so fertilized. This was even true with one year old 

 trees which is contrary to the experience of Emerson,^ but it should 

 be noted that the soil is more conducive to early maturity and the 

 growing season longer in southern Missouri than in Nebraska. 



As to the best means of securing recovery of trees from winter 

 injury, a great deal depends upon the nature of the injury. Thus 

 following the winter of 1899, W^hitten- reports that trees very severely 

 pruned, leaving the branches only a few feet long, recovered much 

 better than trees not headed so severely. Following the severe win- 

 ter of 1904-05 trees rather severely headed-in recovered better 

 than trees that had only one-third or one-half of the previous season's 

 wood cut off. However, Eustace' found that this severe heading 

 back of the trees in New York, following the winter of 1903-04, was 

 very harmful to old trees, though apparently beneficial to young 

 trees. Moderate pruning gave much better results. 



Neb. Agr. Exp. Sta. nul. 79. 1903: (BIbl. No. 33) and Nob. .\gr. Exp. Stn. .\r\l. Kpt. No. 

 19. 1906, pp. 101-10 (Hibl. No, ri.'j). 



Mo. Agr. Exp. Htn. Hul. n.-i, 1902. (Blbl. No. 115). 



'N. Y. (Geneva) Exp. Sta. Bui. um). 190.5. (Blbl. No. 3S). 



