INCREASE IN FLOWER AND YOUNG FRUIT ABSCISSION CAUSED BY CITRUS BUD MITE (ACARI, ERIOPHYIDAE) FEEDING IN THE AXILLARY BUDS OF LEMON

During the course of a 3-yr field study on lemons, 8,467 unopened flow ers were tagged, rated for severity of floral distortions caused by ci trus bud mite, Aceria sheldoni (Ewing), and monitored weekly to determ ine if they developed a fruit or abscised without developing a fruit. Each fruit developing from these flowers was rated for severity of dis tortions caused by citrus bud mite and monitored weekly to determine i f the fruit persisted beyond the June-drop period or abscised before o r during the June-drop period. Abscission rates of both flowers and fr uit increased significantly with increasing bud mite-caused distortion . Distortion rating of fruit was correlated significantly with the dis tortion rating of the flowers from which they developed. The possibili ty that the increased rates of abscission of flowers and young fruit m ay be caused by previously observed decreases in auxin activity and ot her biochemical changes in bud mite-infested axillary buds is discusse d.