• White powdery fungal growth appears on young leaves and also on matured leaves.
• Infected leaves curl, crinkle, role inwards and fall off leaving the petiole attached to the tree giving a broom stick appearance.
• The infected flowers and tender fruits shed.

Management:

• Spary sulphur  3-5 times at 15 days interval.
• Carbendazim 0.1% or Tridemorph 1.5% dusting alternated with sulphur dust 70%
• Carbendazim +wettable sulphur and microsul (52% EC) is also effective.

Image source

http://rubberdisease.blogspot.in/, http://www.apsnet.org/publications/imageresources/Pages/ Rubberleavesinfected.aspx