80 
AMERICAN POMOLOGICAL SOCIETY. 
weather is favorable and the rainfall abundant, as was the case this year, 
the trees may remain in leaf without making any growth till mid-summer, 
then wither on the arrival of the dry days of early autumn. 
On digging large orchard trees of this character last spring, it was found 
In nearly every instance that the upper system of roots was entirely killed, 
while usually the lower extremities of the roots were uninjured. Slight 
injury usually manifested itself by a discoloration of the cambium layer; 
severe injury by a blackening and a more or less complete disorganization 
of cambium and inner bark, apparent as soon as frost leaves the ground. 
In the case of root grafted apples the seedling root was always injured to 
a. greater extent than scion or upper part of the root stock. Where grafted 
apples were not killed it was generally due to the escape of a few roots 
thrown out from the scion part of the stock. The number of trees of a given 
variety which escaped destruction was somewhat but not by any means 
always dependent upon the abundance of the scion root system. The amount 
of surface protection received was a much more important factor. With 
regard to the area over which this injury occurred, Mr. Greene, Secretary 
of the State Horticultural Society, says that “The injury was more severe 
in the central than in the southern part of the state. The injury is greater 
in a belt nearly five counties wide extending across the state from the 
Missouri to the Mississippi river, including Hamilton, Story, Polk and War- 
ren counties. The counties contiguous to this belt have suffered some loss, 
but the injury was not so severe as those included in it.” 
In the center of the geographical area of greatest injury the amount and 
character of the root system exerted less apparent influence upon the ulti- 
mate results than it did along the margins of the affected area where the 
frost was less severe or protective covering more, abundant. Here rooting 
characteristics of scions and hardiness of scions were qualities readily dis- 
cernible. A striking instance illustrating this point was shown in a nursery 
at New Sharon, Iowa, where a block of two year old Jonathan root grafts, 
though protected by weed growth, was completely killed while alongside 
Virginia Crab, Shields Grab and Whitney No. 20 lost only the roots upon 
which they were worked and made fair growth throughout the summer. In 
a different location where the frost was more severe and the nursery un- 
der cleaner culture very few of the crabs escaped. Virginia Crab roots freely 
from the scion. 
INJURY TO NURSERY TREES. 
Apples— In the region worst affected the destruction to one and two 
year old nursery stock was almost complete. Varietal differences manifested 
themselves to some extent in this series as noted above. Inherent hardiness 
with ability to root from scion and depth of planting, were important fac- 
tors. Neglected nurseries fared better than those receiving good cultiva- 
tion. Transplanted nursery trees escaped much better than those not trans- 
planted because set deeper. In one case a row of peach trees was saved 
by the soil thrown up from a drain opened late in the autumn. As to stocks, 
no opportunity presented itself during the course of this study for secur 
ing a comparison of hardiness of stocks except in one instance where a con- 
siderable amount of stock grafting had been done on the Shields and Whit 
ney crabs previously noted. Jonathan, Grimes Golden and Willow Twig, 
as three year top grafts in nursery, came through in good condition. Prof. 
