disease control in Hibiscus

Question

I am a hibiscus grower and have about 50 plants in my home garden. About 30 are planted in the ground, 20 are in fairly large pots.

I have a very heavy infestation of, I think, Whiteflies or Euonymus Scale on these hibiscus leaves. While there are a lot of these on and underneath the leaves, after a few days there is a black greasy coating on the leaves. I spray carbendazim based fungicide and Thiamethoxam based fungicide once every week after watering the plants. I also try to pluck the heavily infested leaves.

But there is no use, as this infestation is not going away. I am really tired of all combinations I have tried. Can you please help me to get rid of this infestation?

I am from Mysore, India.
Thanks
Rith

Answer 1

Both of these pests are insects so fungicides will not be helpful.
Here is some information on euonymous scale control:
http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/insects/scale/euonymus-scale.aspx

Chemical control is not thought to be the best option for whitefly infestations. Neem oil or other natural insecticides may help, but biological control is thought to be the most effective.

Here are some ideas for treating whitefly infestations. Availability of the beneficial insects listed varies by region, but other beneficial insects may be available for purchase in India.
https://www.gardeningknowhow.com/plant-problems/pests/insects/whitefly-control.htm

Here is some additional information on whitefly control:
http://ipm.ucanr.edu/PMG/PESTNOTES/pn7401.html