Increase in Flower and Young Fruit Abscission Caused by Citrus Bud Mite (Acari: Eriophyidae) Feeding in the Axillary Buds of Lemon

Abstract

During the course of a 3-yr field study on lemons, 8,467 unopened flowers were tagged, rated for severity of floral distortions caused by citrus bud mite, Aceria sheldoni (Ewing), and monitored weekly to determine if they developed a fruit or abscised without developing a fruit. Each fruit developing from these flowers was rated for severity of distortions caused by citrus bud mite and monitored weekly to determine if the fruit persisted beyond the June-drop period or abscised before or during the June-drop period. Abscission rates of both flowers and fruit increased significantly with increasing bud mite-caused distortion. Distortion rating of fruit was correlated significantly with the distortion rating of the flowers from which they developed. The possibility that the increased rates of abscission of flowers and young fruit may be caused by previously observed decreases in auxin activity and other biochemical changes in bud mite-infested axillary buds is discussed.