Etiology and control of some mango blossom diseases in South Africa.
Lonsdale J. H., Kotzé J. M.
Author Affiliation: Merensky Technological Services, P.O. Box 14, Duiwelskloof 0835, South Africa.
: 345-352
Abstract : Nattrassia mangiferae was consistently isolated from blighted mango inflorescences collected in July-September in 1989 and 1990 in the Transvaal Lowveld, South Africa. Isolates of N. mangiferae caused blossom blight when artificially inoculated on healthy panicles. Alternaria alternata and Colletotrichum gloeosporioides [Glomerella cingulata] were found to cause small, dark, necrotic lesions on mango inflorescences. Blossom blight seems to develop due to systemic infection by N. mangiferae. The incidence of blossom spot was positively correlated with rainfall. Oidium mangiferae infected once flowers had begun to open on the panicles (3-5 weeks after budbreak). Prior to this period and during fruit set, no significant O. mangiferae infection occurred. Various fungicides, sprayed at fortnightly intervals during flowering, were screened for their efficacy in controlling blossom blight, blossom spot and powdery mildew. Flusilazole or pyrazophos resulted in significant control and consistently increased fruit set and yield above the untreated controls.