Spots on underside of Rangpur foliage

8 years ago

I was inspecting my Rangpur for spider mites today and noticed some discolored spots on the undersides of the leaves. Background - I sprayed the tree with Neem a week ago because I noticed a small amount of spider mite webbing and wanted to control the pests before they got out of hand. The leafs came from the top of the tree closest to the lighting they're under. Could this be a result of the neem spray or is it something else?

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Comments (3)

Susanne Michigan Zone 5/6
8 years ago
fungus maybe? no idea but following
tropicofcancer (6b SW-PA)
8 years ago
It could be oil damage from neem - I am guessing here. This can happen when the neem oil or any oil based pesticide is not properly mixed/dispersed in water. Leads to drops of pure oil hitting the leaves and causing damage. I have seen similar and worse damage before. You can use insecticidal soap, protekt or emulsifier such as polysorbate (tween20) to help with proper mixing.

Horticultural oils have warnings about not applying when the light is intense, under very humid conditions and when temperatures are too low or high. Indoors I usually separate the plants that are sprayed and keep them in a darkish place in the basement for a day. Or apply after the lights turn off.
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johnmerr
8 years ago
Maybe edema.