Assessment of spray application of mono-potassium phosphate as a non-chemical measure to control powdery mildew (Oidium mangiferae) in mango inflorescences.
Oosthuyse S. A.
Author Affiliation: HortResearch SA, PO Box 3849, Tzaneen 0850, South Africa.
27 : 68-70
Abstract : Monopotassium phosphate [potassium dihydrogen phosphate] (MKP) has been found to be effective in suppressing powdery mildew in mango (caused by Oidium mangiferae) inflorescences. The efficacy of MKP as a control measure for powdery mildew was evaluated in South Africa during 2006 with respect to the application date (commencement of bloom or full-bloom), MKP concentration, and the inclusion of a surfactant (Sanawett). In the first experiment, 2% MKP/Sanawett (20 ml/100 litres of water) and Folicur/Sanawett (20 ml/100 litres of water) were the most effective when applied at the commencement of anthesis. The inclusion of a surfactant increased the efficacy of MKP in controlling powdery mildew. In the second experiment, MKP at 1.0, 1.5 or 2.0% w/v was applied at two stages of inflorescence development (commencement of anthesis or 80% bloom). MKP application at the commencement of anthesis was superior to application during flowering when symptoms became apparent. MKP rates of 1.5 and 2.0% were equally effective and as effective as Folicur sprays. Fruit set and degree of inflorescence colonization were, generally, negatively correlated. The results showed that MKP is an effective control measure against powdery mildew in mango, particularly when applied at 1.5 or 2% with a surfactant at the commencement of anthesis.