First Report of Rust Caused by Tranzschelia discolor f. sp. dulcis on Almond in India. R. C. Sharma, Department of Mycology and Plant Pathology, University of Horticulture and Forestry, Solan-173230, India. K. K. Jindal, and V. K. Gupta. Department of Mycology and Plant Pathology, University of Horticulture and Forestry, Solan-173230, India. Plant Dis. 71:850. Accepted for publication 5 May 1987. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0850A.
During a survey of diseases of stone fruits in Himachal Pradesh, India, in 1985, a previously unrecorded rust of almond (Prunus dulcis (Mill.) Webb.) was observed. The pathogen was identified as Tranzschelia discolor f. sp. dulcis (Fuckel) Tranz. & Litv. on the basis of morphological and pathological characters (2). Symptoms are first evident as pale yellowish spots on both leaf surfaces. These later become bright yellow islands on the upper leaf surface, while the cinnamon brown, dusty pustules of the rust fungus appear on the undersurface. Heavy infections result in early leaffall. Severe rust infections (40-70%) were recorded on the cultivars Nonpareil, Texas, and Drake. Koch's postulates were fulfilled on detached leaves maintained on water agar by inoculating spores collected from naturally infected plants (1). T. discolor also occurs on apricot, peach, and plum in this region.