Powdery mildew on mango - control early.
Schoeman M.
Inligtingsbulletin - Instituut vir Tropiese en Subtropiese Gewasse : 5-7
Abstract : Powdery mildew of mangoes, caused by Oidium mangiferae, is widespread throughout most of the mango growing areas of South Africa. The damage caused by powdery mildew is often underestimated as disease outbreaks occur early during the flowering stage. The fungus attacks young tissue of all parts of the inflorescences, leaves and fruit. Initially, small isolated patches of powdery white mycelium develop on affected organs. These may later coalesce to cover large areas of the plant. Effective control of powdery mildew is essential for good fruit set. Certain chemicals are registered for use against powdery mildew and these are listed. Most recommendations for the first application are at 50% bloom. However, research has indicated susceptibility from the time individual flowers start to open from the bottom of the inflorescences i.e. at 20% bloom. With most cultivars this is usually during July. Spore counts also showed that in the majority of mango growing areas, the first spores were released between the beginning and middle of July. It is therefore important to spray earlier, i.e. before the first symptoms appear. By spraying preventatively (mid to end of July), control will be more effective and fewer sprays will be necessary.