Pakistan Gardening Forum

Dear All,

I am encountering this problem with my hibiscus, the leaves are showing yellow spots and are curling. there are no spider mites, no mealy bugs and any other visible pest. I have sprayed it with mitecide and pesticide...

Kindly let me know how to cure this:

Izhar wrote:Dear All,

I am encountering this problem with my hibiscus, the leaves are showing yellow spots and are curling. there are no spider mites, no mealy bugs and any other visible pest. I have sprayed it with mitecide and pesticide...

Kindly let me know how to cure this

ASA, If there is no visible pest, then it must be some nutrient deficiency. If the soil is too acidic, due to fertilization, calcium may be depleted. May be time to change the pot soil as well.

The soil pH is just over 7 (most soils here are around 8), the plant is given diluted NPK with trace elements on weekly basis...

My thinking was the same though as to change the soil, trim the roots and cut off all the leaves... so as to give it a fresh start...

Doesn't seem to be curl virus as leaves of plants infected with this virus are severely twisted which doesn't appear in this case. It makes sense to change the add some compost to the medium and cut the severely infected leaves and later on when the plant starts exhibiting new growth then give it a nitrogen boost which hopefully should spur new leaf growth.

And did you apply any copper fungicide to this plant?

can you please show the back side of leaves?

I doubt if there will be any aphids beneath the leaves.

The more i think about it it's some sort of virus (definitely not a curl virus). I would say 60% chance it's virus and 40% that it may be nutrient deficiency. There's aren't any effective chemical treatment for viruses. You would need to resort to cultural controls by removing the effected leaves and then burning them. Also avoid composting effected material which should be burned with the leaves. Thus remove the leaves and replant using some other compost. Do make sure to disinfect your secateurs after usage.

The thing about viruses is that they are spread through many ways e.g. sometimes using infected secateurs, infected hands, or through carriers such as sap sucking insects like aphids, leafhoppers, whitefly or some types of soil dwelling microscopic worms.

I would suggest first changing the medium and try to rectify the deficiency in nutrients. In case if it doesn't work out then resort to the cultural control mentioned above.

Backside:

Izhar spray for mites. Biphenthrine or Oberon. Stop all phosphates, give potash and some iron.

Dr. sb. oberon spray has been done... i second your though on toxicity of Phosphate..

Sometimes you can't see some types of mites. If you put the leaf between your thumb and index finger and swipe with gentle pressure on the leaf and then see streaks of brownish reddish residue on your thumb and finger then likely it is some mites (you just crushed). However, if you've sprayed insha'Allah problem is resolved and you should be fine with some potash and iron to boost the plant. Super-thrive if available is excellent to boost stressed plants also. Hopefully new foliage will be well.