EFFECT OF THE DISEASE ON APPLE TREES. 39 
Of these 5 healthy and 7 diseased ones died from the effect of trans- 
planting to the orchard. During the fifth year 10 healthy and 12 
diseased trees died, and during the sixth year 4 healthy and 9 dis- 
eased trees died. It should be noted, however, that all of the trees 
that died during the fifth and sixth years and 3 trees during the 
first four years were killed by borers encircling the trunk near the 
surface of the ground. In no case could their death be directly 
attributed to crown-gall or hairy-root, nor can it be said that borers 
prefer the diseased trees to any marked extent. 
Tables XVIII and XIX, in the appendix, show the number of 
healthy and diseased trees of each variety planted in orchards 1 and 2, 
as well as the number of each that died during six seasons of growth. 
The diseased trees of the variety Collins in orchard 2 had soft galls 
on the roots. All of the other galls were of the hard form. — 
A third orchard, designated as ‘‘orchard 3,’ was planted in the 
latter part of April, 1907, with 1,108 well-rooted apple trees of a num- 
ber of varieties selected from trees grown in experiments in the 
nursery. Of these 572 were healthy, 354 diseased with hairy-root 
(Pl. I, fig. 2), and 117 diseased with crown-gall of both the hard and 
the soft forms. The trees were transplanted after the buds were 
greatly swollen, and a month of dry weather ensued just after the 
planting. As a result, the loss from transplanting was heavy. A 
fire in the autumn of 1908 killed many of the trees and ruined the 
experiment. The trees were then dug, no notes being taken at the 
time of digging as to the condition of the roots. The trees that died 
in 1907 and 1908 are enumerated in Table XX, in the appendix. 
By combining the data for 1907 and 1908 in Table XX, it is found 
that in two years 33.4 per cent of the healthy trees died, and at the 
same time 37.3 per cent of those diseased with crown-gall and 25.1 
per cent of those diseased with hairy-root. Again it must be said 
that the reason for the increased vitality of the trees diseased with 
hairy-root is the greater tendency to throw out roots. This has 
already been mentioned in the case of seedlings affected with hairy- 
foot (see pp. 24 and 34). On the other hand, the trees diseased with 
crown-gall had slightly less vitality, since a somewhat greater number 
died. 
A fourth experimental orchard, partly described on page 79, was 
planted on the Potomac Flats, near Washington, D. C., in 1907 and 
transplanted to the experimental farm at Arlington, Va., m 1908. 
Trees of the following varieties, grown in a nursery in eastern Mis- 
souri, were planted: Jonathan, Grimes, and Gano. The trees dis- 
eased with crown-gall and hairy-root were selected on account of their 
having intense forms of disease, in addition to possessing as abundant 
roots as the healthy trees. During the two years that have elapsed 
186 
