This black fungus may cover the leaves and fruit so completely that it interferes with the proper physiological activities of the trees. Heavily-infested trees become weak and produce small crops of insipid fruit. Also, fruit covered with sooty mold will be retarded in ripening and late in coloring, especially the upper part, which may remain green after the lower portion has assumed the color of ripe fruit. The fruit often must be washed before it is put on the market. A secondary injury to the trees may result from an excessive increase of the common scales of citrus which find protection under the sooty mold that covers leaves and branches.
Whiteflies become a problem when they continually sap the plant of energy needed for growth.
This occurs when there is constant flushing and availability of new growth, such as after severe hedging and topping. Cultural Control A regularly maintained program of hedging and topping can help avoid whitefly problems. A yellow fungus, Aschersonia goldiana , does not attack the citrus whitefly, but is very effective against the cloudywinged whitefly. The presence of the yellow fungus guarantees that cloudywinged whitefly is present. These fungi are generally present in all citrus groves in Florida and increase in numbers when the proper environmental conditions prevail.