306 REpPorRtT OF THE BOTANICAL DEPARTMENT OF THE 
It was shown by inoculating Bacillus into the bark of apple 
trees that the typical cankers resulted, and also that twig 
blight could be produced by introducing the organism into the 
bark of pear and apple twigs. It is suggested that Bacillus 
cankers may be expected in any region where fire-blight of 
pear and apple is prevalent. 
Wolf River and Tolman Sweet appear to be resistant, while 
Baldwin and Ben Davis are very susceptible. 
Blighted water sprouts and short spurs, which had been 
infected with Bacillus through insect and other injuries, were 
said to have been the beginning points of many cankers of 
trunks and branches. Pruning and other wounds are consid- 
ered important places of infection. It is advised that cankers 
be cut out, disinfected with a corrosive sublimate or a copper 
sulphate solution and then painted over with some heavy lead 
paint; also that all dead twigs and water sprouts be pruned 
out, disinfecting and painting the wounds. 
REVIEW OF LITERATURE ON ARSENIC-INJURY TO 
FRUIT TREES. 
A rather interesting addition to the Crown-rot discussion 
is contributed by W. P. Headden* under the caption, “Ar- 
Senical poisoning of fruit trees.” Headden holds that the root 
and trunk injuries described by Whipple *® on Ben Davis and 
Gano are typical cases of arsenical poisoning (a possibility 
suggested by Whipple), and that Spitzenburg, Early Harvest, 
Wolf River, Lawver, Blacktwig, Baldwin, Jonathan, Grimes 
and Pewaukee are also affected. 
It is stated in the bulletin that the excessive application of 
arsenical sprays, as practiced in some sections of Colorado to 
combat the codling moth, and the consequent accumulation of 
arsenic under the trees are suflicient to injure or kill them. It 
was estimated that 0.9 pound of arsenate of lead, or 0.225 


7 Colo. Agrl. Expt, Sta. Bul. 131. 1908. 
7° Colo. Agrl. Expt. Sta. Bul. 118. 1907. 
