Diseases of economic plants (1910) Diseases of economic plants diseasesofeconom02stev Year: 1910 DISEASES OF SPECIAL CROPS 107 This disease of pears is particularly abundant upon sev- eral varieties of the Japanese strain. Bitter rot, ripe rot (Glomerella rufomaculans (Berk.) Spaul. & von Schrenk). — This disease is of much less frequent occurrence upon the pear than upon the apple. For description and treatment, see pp. 64 and 74. Fig. 44. — Scab on California pears bought in Raleigh. Original. Powdery mildews, sphaerothocose and podosphaerose. — See apple. Scab (Venturia pyrina Aderh.).
Diseases of economic plants (1910) Diseases of economic plants diseasesofeconom02stev Year: 1910 DISEASES OF SPECIAL CROPS 107 This disease of pears is particularly abundant upon sev- eral varieties of the Japanese strain. Bitter rot, ripe rot (Glomerella rufomaculans (Berk.) Spaul. & von Schrenk). — This disease is of much less frequent occurrence upon the pear than upon the apple. For description and treatment, see pp. 64 and 74. Fig. 44. — Scab on California pears bought in Raleigh. Original. Powdery mildews, sphaerothocose and podosphaerose. — See apple. Scab (Venturia pyrina Aderh.). — This scab much resembles that of the apple and consists of a surface blotch or scab, often accompanied by a peculiar cracked appearance of the skin. This symptom, however, is a secondary effect which is not necessarily present. Upon the twigs rough cankers are formed. Smith1 of California recommends plowing under or clearing away dead leaves and using a dormant spray fol- lowed by two applications of Bordeaux mixture while 1 Smith, R. E., Cal. Agr. Exp. Sta. Bui. 163, p. 17,1905.
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