Timing of fungicide applications for control of postbloom fruit drop of citrus in florida
Timmer, L.W.; Zitko, S.E.
Plant Disease 76(8): 820-823
1992
ISSN/ISBN: 0191-2917 Accession: 007953397
Fungicide application schedules of benomyl or captafol for control of citrus postbloom fruit drop caused by Colletetrichum gloeosporioides were evaluated in three orchards [Citrus simensis] during the 1989-1991 bloom periods. In seasons and location where disease incidence was low, a single application of either fungicide at midbloom or two application of either fungicide at midbloom or two applications one at early bloom and one at midbloom, reduced blossom blight incidence and the formation of persistent button (floral disk and calyx). Where disease incidence was great, only weekly or 10-day schedules provided a high degree of control of blossom blight and button formation. The number, rather than timing, of application during the bloom period appeared to be the primary determinant of the degree of disease contr. Blossom blight incidence and button formation decreased exponentially as the number of application increased in many cases. When disease incidence was low or moderate, fruit counts or total yields were not increased by any application schedules. In one cases, when disease incidence was high, fruit counts were increased about sevenfold and total yield was inceased threefold when applications were made every 10 days, but other application schedules in the same experiment did not increase fruit counts or yield.