Title : White peach scale
Visit Count : 4177 Time(s)
Upload Date : 1/7/2016 - 7 Year(s) ago
Category : Stone fruit
Thursday, January 7, 2016
Visit Count : 4177 Time(s)
Upload Date : 1/7/2016 - 7 Year(s) ago
Category : Stone fruit
Pest Name:
White peach scale, Pseudaulacaspis pentagona Targioni Tozzetti, 1886 (Hemip: Diaspididae)

Economic Significance:
Pseudaulacaspis pentagona is a kind of pest that lives on the trunk and shoots of many important host plants, such as peach, almond ,cherry, walnut, mulberry, kiwifruit and olive. The white peach scale will infest the bark, fruit and leaves of plants, thus making it a “triple threat” to growers. As a result, infested trees may be declined and destroyed. white peach scale destroyed numerous peach orchards in Mazandaran in recent years.

Morphology
Eggs are deposited on the surface of the host plant. They range in color from orange to white indicating female and male offspring respectively. Eggs of an intermediate color may also be evident which can produce offspring of either sex. The larvae will hatch from the egg case within approximately three to four days after being laid. The young crawlers will soon settle on an area of the host plant and insert their stylets into the plant to begin feeding. The larvae will undergo two to five molts, depending on their sex.The adult female scale is immobile on the host plant. She is covered with a protective shell, which is created by incorporating the cast skins from her previous molts with newly secreted wax from her body glands. She may also gather pieces of bark from the host plant to add to her shell, which then serves as protective camouflage. The appearance of the female is dull white to yellowish in color, oval in shape, with an overall length measuring between 2.0 to 2.5 mm. Males of the white peach scale begin building their armor after their second molt and their covering appears as a long white to yellowish colored shell. The males will molt three more times, eventually emerging as an orange colored adult and living only for a period of approximately 24 hours. Unlike females of this species, adult males possess wings in order to be mobile for mate location. The adult male body length is approximately 0.7mm with a 1.4 mm wingspan.

Biology
The life cycle of the white peach scale depends upon the climate in which it resides. White peach scale has three or four generation in Mazandaran province. The first generation is around early may ( Ordibehesht), the second is in early July ( Teer),and the third is in early September ( Shahrivar).The adult females of the white peach scale begin laying eggs approximately two weeks after mating and will continue to lay eggs for eight or nine more days. After the female has finished the oviposition or egg-laying process she will soon die. An interesting phenomenon of the egg laying process is that the eggs which are deposited first are orange in color and will become female offspring, while the eggs that are laid later are white and will give rise to male offspring. The
average number of eggs produced by each female will vary due to several factors, but is primarily influenced by the species of the host plant that is being infested. In Georgia, it was reported that female scales laid an average of 100 eggs when peach trees served as the host plant. The eggs
hatch three to four days after being deposited and young
crawlers emerge.

Control:

Biological:
Several predators feed on white peach scale. Primarily, these species include Chilocorus bipustulatus (mainly in Mazandaran) and ladybird beetles (Coleoptera: Coccindellidae).A parasitoid wasp, Encarsia diasapidicola can useful for this purpose but at first The wasp must be tested under laboratory conditions for white peach scale control.

Chemical:
Management of the white peach scale in winter with traditional methods (insecticidal oils same as Volk oil or Dormant oil) is difficult as the scales protect themselves very effectively with their hard, waxy armor. Control methods are often best directed at the larval or crawler stages in spring, which are the most vulnerable. As insecticide recommendations and regulations are updated yearly, Pyriproxyfen (0.5- 0.75ml/lit) and Chlorpyrifos (2 ml/lit) are the current insecticides that advised for control this pest in recent years.

Preparation: Zakkie Ahmadi
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