My grapefruit tree always suffers from sooty mould. I use white oil to get rid of it, but after a while (maybe few mos. or so), it comes back again. It's a never ending spray of white oil. However, it still gives me lots of fruits w/c is the main thing. Here's the pic of my beloved grapefruit tree.. The file exceeds the limit, I'll try to send next time..
The probable cause your tree gets sooty mold is because of the secretions from various insects. Control the bugs, and your tree will not get the mold. - Millet
Yah I know all these insects secretions esp. from ants. I dust the tree trunk w/ lots of insect's powder against ants,roaches, etc..., I spray the tree w/ white oil & puts it under control for a while.W/ all these probs, the tree still giving us lots of fruits. I wish I could show you the pic but I don't know how to reduce the size of my picture's file. I can only reduce it via email. Is there any other ways?