Perhaps one of the gardening fraternity can point me to a remedy available in Thailand.

Our Custard Apple and Guava trees suffer frequent outbreaks, Have tried unsuccessfully to source White Oil or Winter Oil here as these are the usual remedies I used in Oz to treat these pests.

Neem?

Just plain old cooking oil with a dash of kitchen detergent to add a bit of extra stickyness . It will need to be done when needed - usually just once will not be enough .

See the management notes in these IPM links.

http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74108.html

http://www.ipm.ucdavis.edu/PMG/GARDEN/PLANTS/INVERT/woolaphids.html

As you know, sooty mold grows on the 'honeydew' deposits on leaves below where the aphids are feeding. Control the aphids and you will control the sooty mold.

• Control the ants which farm the aphids for their sweet honeydew, and protect them from natural predators.
• Don't overfertilize, including manures.
• Thin the trees to promote air and light circulation.
• If the trees are not big or numerous, you can use mechanical methods to wipe off the aphids with water spray or gloved hand, to reduce aphid population .
• Spray as a last resort, because pesticides will kill beneficials too.