H,i I've 2 citrus trees that have scale and black sooty mould. I've treated them with home made while oil and was wondering how often I should treat them? Should I wash the leaves of the tree the next morning after applications of white oil? I live in Queensland Australia the garden is subtropical, it's now mid winter we have about 45 inches of rain per year that falls mostly in summer. One tree is a lemon and the other is an orange they are older trees, they were mature trees when we purchased the block 5 years ago. Would love some advice as I love the trees. Cecily
From what I read on Wikipedia, white oil, know here (Vancouver, BC, Canada) as mineral oil, works by blocking the breathing pores of insects so is effective against scale, but would not be effective against sooty mould. However sooty mold alone does not harm plants, other than shading the leaves and looking unsightly. If you get rid of the scale the sooty mould may also go away.
