Killing of Plant Tissue by Low Temperature 287 



freezing peaches in the laboratory, the tissue kills in the following 

 order, beginning with the most tender: the veins surrounding the 

 seed, the kernel, the flesh. When the peach has reached considera- 

 ble size, the woody covering surrounding the kernel is most hardy. 



The greater tenderness of the seed may be accounted for by 

 the difference in sap density. Thus the freezing point depression 

 for the seed kernels, when they are large enough to separate from 

 the seed practically, was found to be 0.765 C, while that for the same 

 fruit with the kernels excluded was 1.075. 



At Koshkonong and at Goodman in 1908, following the freeze 

 of April 30th, the fruit was injured least on the young vigorously 

 growing trees. Thus at Koshkonong in the orchard of Mr. \V. C. 

 Paynter, weak trees in various parts of the orchard and trees on 

 rocky, uncultivated portions had all the fruit killed, while vigorous 

 trees further down the hill where the temperature must have been 

 lower, as well as further up the hill, bore a full crop. In the case of 

 killing of buds in winter, whether they have been started into growth 

 or not, and in the case of killing of blossoms in spring in the southern 

 part of Missouri, in some years the Elberta is one of the most tender 

 varieties. Yet where it is the young fruit that is killed, the Elberta 

 seems to be one of the most hardy varieties, at least other varieties 

 were killed to a larger extent than Elberta in that year. Early 

 varieties where the fruit was large at the time of the freeze uniformly 

 killed worse than later ones. In Missouri, at least, early varieties 

 do not bloom earlier than late varieties like Salway. In fact in ex- 

 treme South Missouri such early Chinese Cling varieties as Sneed, 

 Victor and Carman, on account of their longer rest period actually 

 bloom later than late varieties like Elberta or Crawford's Late or 

 Heath Cling, yet from the time of pollination there is much more 

 rapid growth of the young fruit of the early varieties. Thus when 

 the calyx tube is dropping from the Elberta peaches, the young 

 Sneed will be much larger. 



As to means of handling the trees to avoid injur>- at blooming 

 time or after fruit is set, there is not so much that can be done except 

 that, as mentioned above, in the most southern portions of the peach 

 belt it is possible, by increasing the vigor of the tree, to cause the 

 blooming to be later and, therefore, the young fruit at any given tinu' 

 after the bloom falls, to be smaller when the frost might come. 

 This, of course, would not apply further North. Vigorous, trees 

 may also have their fruit killed to a smaller extent because, in their 

 tendency to make wootl growth, the truit develops apparently more 

 slowly, at least fruit is practically alwaj's later in ripening on \ ig- 



