Cork scars on fruits of the citrus variety 'Sweetie' as related to infestation by the citrus mealybug.
Investigations in Israel were performed into the relationships between the feeding of the citrus mealybug (Planococcus citri) and the development of cork scars (necrosis) in grapefruits, cv. Sweetie (Citrus paradisi × C. grandis [C. maxima]) orchards and to determine the timing of injury as related to fruit development. Limiting P. citri infestation to certain development stages of the fruit was achieved by chlorpyrifos application and artificial infestation. The appearance of cork scars was directly related to the level of P. citri infestation in fruits. The majority of injuries became evident in the 1st and 2nd P. citri generations. Application of chlorpyrifos in early April (prior to blooming) prevented cork scars, whereas application in early summer (mid-June) only reduced damage. Cork scars in the Sweetie cultivar were caused by a rather low P. citri population, during the early stages of fruit development (between early May and mid-July) and before the natural enemies of P. citri became fully active.