Sept. 8 1923 
Origin and Control of Apple-Blotch Cankers 
417 
(10) Dormant sprays of concentrated lime sulphur (1 to 3) did not 
influence canker development, although spores already present in the 
pycnidia may have been killed. Subsequent petiole infection was not 
checked. 
(11) Sulphur and Bordeaux dusts were unreliable in the prevention 
of petiole infection and canker formation. 
(12) Bordeaux 4-6-50, and 2-4-50 as well, applied 2, 4, and 6 weeks 
after petal-fall prevented petiole infection and subsequent canker forma¬ 
tion. Under certain conditions an earlier spray application is necessary. 
Lime sulphur i° or 1 to 40 was not as reliable as Bordeaux. 
(13) In old orchards certain varieties are more severely cankered than 
others and are harborers of the disease. Cankers are most abundant in 
the lower parts of the tree. Individual trees show more or less constant 
differences year after year, in the degree of infection. 
(14) Cankers have been found on a considerable percentage of the trees 
in young orchards, especially Oldenburg, on the trunks and older limbs. 
The infected trees were scattered and there was evidence of disease intro¬ 
duction with the nursery stock and very little evidence of tree-to-tree 
spread in young orchards. 
(15) Cankers have been found in great abundance on nursery stock on 
both stock and scion and on seedlings used for budding purposes. The 
evidence indicated that the nursery row afforded ideal conditions for the 
spread of blotch. 
(16) It has proved feasible to eradicate the blotch cankers from young 
orchards by pruning cankered spurs and small branches and by excising 
the cankers on the larger limbs. The cankers are shallow and can be 
shaved off with a sharp knife in the early spring without injury to 
the underlying cambium. To remove all the mycelium the cuts must 
be deep enough to remove all the discolored tissue and must extend 
about 1 cm. beyond the visible margin of the canker. Healing occurs 
rapidly and no disinfectant or wound dressing has been necessary. 
(17) By canker eradication and annual application of the blotch sprays 
to prevent the formation of new cankers, it seems entirely possible that 
the future blotch menace in young orchards may be avoided. 
LITERATURE CITED 
(1) Anderson, H. W. 
1920. DISEASES OR Illinois fruits. Ill. Agr. Exp. Sta. Circ. 241, 155 p., 00 
fig., 2 col. pi. 
(2) - 
1921. THE NORTHWARD ADVANCE OF APPLE BLOTCH AND HOW IT MAY BE 
checked. In Trans. Ill. State Hort. Soe., n. s., v. 54,1920, p. 234-237. 
( 3 ) - 
1923. orchard sanitation. In Trans. Ill. State Hort. Soc., n. s., v. 56, 1922, 
p. 381-389. 
(4) Curtiss, C. F., and Brown, P. E. 
1921. botany and plant pathology. In Iowa Agr. Exp. Sta. Ann. Rpt., 
1921, p. 30-36. 
(5) FreiEnmuth, William. 
1922. blister canker and apple blotch. In Bien. Rpt. Kans. State Hort. 
Soc., v. 36, 1920-21, p. 140-145. 
(6) Gardner, Max W. 
1922. origin of apple-blotch cankers. (Abstract.) In Phytopathology, 
v. i2,p. 55. 
(7) - Greene, Laurenz, and Baker, C. E. 
1923. apple blotch. Indiana Agr. Exp. Sta. Bui. 267, 32 p., illus. 
( 8 ) -and Jackson, H. S. 
1923. new aspects of apple blotch control. (Abstract.) In Phytopathol¬ 
ogy, v. 13, p. 44. 
