This is a foliar disease in nurseries, vegetative multiplication areas, seed and clonal orchards of important forestry species viz., Acacia, Albizia, Bamboos, Dalbergia, Eucalyptus, Gmelina, Melia, Neem, Cadamba, Sandal, Teak, etc. 

    Many forestry species such as Acacia, Albizia, Bamboos, Dalbergia, Eucalyptus, Gmelina, Neem, Cadamba, Sandal, Teak, etc.

   This disease is caused by Oidium azadirachtae on Neem,  Phyllactinia suffulta var. gmelina on Gmelina arborea and  members of the family Erysiphaceae have been recorded to cause mildews in Teak. Phyllactinia corylea is recorded to attack Teak laves. Phyllactinia guttata is also recorded to attack Teak in other countries. Uncinula tectonae, widely occurs in nurseries and forests in central and southern India. Phyllactinia dalbergiae causes powdery mildew on Dalbergia sissoo seedlings.

1. White patches will be seen on the surface of the leaves. These patches coalesce and cover the whole leaf lamina giving grayish white appearance. 

2. Severely infected leaves and leaflets are defoliated prematurely.

3. In case of Gmelina arborea, the pathogen produces infection spots on the lower surface of the leaves with corresponding pale yellow colour on the upper surface.

4. In case of Dalbergia sissoo, the fungus produces yellowish, persistent, dense mycelium on the lower surface of sissoo leaves.

   The disease can be managed by an integrated approach involving measures such as sanitation, cultural practices and use of fungicides. The disease can be effectively controlled by foliar spray of Bavistin fungicidal solution (0.01%). Sulphur dust is most effective in controlling powdery mildew in two year old seedlings of Teak followed by Baycor, Mortesan and Calixin fungicides.  Application of sulphur based fungicide has been found most effective followed by Baycor, Mortesan and Calixin in controlling powdery mildew disease on D. sissoo seedlings in nursery.