Question
I have purchased 2 Florida King peach trees and for 3 years they have developed small white fungus type spots all over the tree and now their new branches are black.  I can wipe off the black, and there is green underneath this, but it is a long process and wipes off the buds too and it seems to be killing the tree.  Any ideas how to save my peach trees?  Thanks - Georgia Fotsch
P.S.  I live in Beaufort, SC

Answer
Sounds like either Aphids or scale insects. These insect suck the plant juices from the plant. This secretion is called honeydew because it is high in sugar content. A fungus called sooty mild will grow on this honeydew which is the black you are seeing. To control the sooty mold you will need to control these insects. I would guess the insect you have is a scale. scale insects are in a hard covering and look like small turtle shells on the twigs. If these are squeezed they contain a liquid.

The adult female scales are difficult to control with insecticides because of their hard, waxy covering. Horticultural oil or dormant oil can be applied before budbreak when the temperature is above 40 癋. These oils work by smothering the overwintering adult females, and they offer the best control when applied during the dormant season. Spray the trunk and limbs with 1 to 2% oil solution to the point of run-off. If the scale problem is serious, fall applications applied during the first cool spell after full leaf drop should be considered. These oil sprays during the dormant season will also help control mite infestations, as they survive the winter on the bark.

Chemical control of the crawlers only can be achieved with malathion, carbaryl, permethrin or esfenvalerate which are available in homeowner size packaging. Additionally, sprays for controlling scale should be applied about  May 1, July 1, and September 1. Do not spray insecticides during bloom. Do not apply malathion within 7 days of harvest, carbaryl within 3 days of harvest, and permethrin or esfenvalerate within 14 days of harvest. As with all pesticides, read and follow all label directions and precautions.
Wet the foliage and the twigs to the point of run off. These insecticide will also kill any aphids that maybe present.