Q.sticky substance on leaves an white fungus
I have sprayed with malathion, but no results.
Certified GKH Gardening Expert
Is the white stuff fuzzy, web-like or powdery in nature? This could be either some type of pest (mealybug, scale, or spider mite) or fungus (powdery midew). The stickiness is normally the result of a pest, however. Neem oil will help with all of these. It's both an organic insecticide and fungicide. Here is more information that should help: https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm
https://www.gardeningknowhow.com/plant-problems/pests/mealybugs-white-residue-on-plants-leaves.htm
https://www.gardeningknowhow.com/plant-problems/pests/scale-bug-how-to-control-plant-scale.htm
https://www.gardeningknowhow.com/plant-problems/pests/insects/spider-mite-treatment.htm
https://www.gardeningknowhow.com/plant-problems/disease/powdery-mildew-homemade-and-organic-remedies.htm