The persimmon tree (Diospyros kaki Linn) is also known as the Oriental persimmon, Japanese persimmon and Kaki. The persimmon is native to China, and has over 2,000 cultivars. In the mid 1800s it was brought to California. According to the University of Florida Extension, scales--predominantly white peach scale--attack the wood on the branches and trunk of the persimmon tree.
Two types of scales exist: armored scales and soft scales. White peach scale is an armored scale. Ornamental trees that can be attacked by scales include persimmon, chinaberry, flowering peach, French mulberry, lilac, walnut, catalpa and privet. These small insects (1 to 2.25 mm in diameter) feed on the fruit, bark or leaves of the persimmon tree, which can cause stunting, leaf drop and branch dieback. Scales are dull white to yellow in color, with an oval shape. Due to their miniscule size they may be hard to detect before the damage actually appears.
The white peach scale life cycle is dependent upon the climate. For example: northern states produce two generations of scale per year, and southern states can have twice as many generations per year. Adult females mate and begin depositing eggs in early spring (in the Southeast approximately April 1). They will continue to lay eggs for around 30 days. Once the adult female is finished laying eggs she will die. There is a sequence to the egg laying, with the female eggs being laid first (orange in color; male eggs are white). The eggs hatch in approximately three to four days, and soon begin feeding. As the larvae mature they will molt two to five times--the number of molts depends upon their sex.
The natural predators of white peach scale are ladybird beetles, common lacewings and some gall midges. If the infestation is small then the best means of control is to prune away the infested branches (be sure to destroy the infested plant material). However, if it is a severe infestation then an insecticide or pesticide will be required. Due to the armor/hard covering of the white peach scale, chemical control should be applied when the scales are young/larvae before the armor is developed. It will probably take two chemical applications (seven to 14 days apart) to get the infestation under control.
The University of Florida lists the following pesticides that can be used on scales: Black Leaf Dormant Spray, High Yield Dormant Spray, Orthorix (dormant), Provado 1.6F, Ringer Soap, Safer Soap and Scaleside.
Besides scale the persimmon tree can be attacked by persimmon psylla, twig girdlers, borers, wood boring insects and stink bugs. There is no reason to apply chemicals to the tree unless you are certain that these pests are present, or if you had a problem with them the previous year. Spraying sometimes kills off the natural enemies of other pests such as aphids, mites and leafminers, which will allow those pests to become a problem.