Uptake of Imazalil by Citrus Fruit After Postharvest Application and the Effect of Residue Distribution on Sporulation of Penicillium digitatum. G. Eldon Brown, Scientific Research Department, Florida Department of Citrus, Citrus Research and Education Center, Lake Alfred 33850. David J. Dezman, Scientific Research Department, Florida Department of Citrus, Citrus Research and Education Center, Lake Alfred 33850. Plant Dis. 74:927-930. Accepted for publication 4 May 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0927.

Imazalil applied to citrus fruit after harvest moved into the rind while the fruit were wet from the treatment. Imazalil was absorbed by the epicuticular wax and cuticle within a wetness period lasting 1–3 min, but less than 1% of it moved through the cuticle during this period. However, 30–45 min after fruit were dipped in imazalil (1,000 ?g/ml) for 15 sec, the fungicide was recovered from tissue deeper than 1 mm into the rind. About 40% of the applied imazalil remained on the fruit surface after the fruit dried. At comparable treatment concentrations and times, significantly more imazalil adhered to fruit that were dipped than to fruit treated with a nonrecovery spray over brushes saturated with the fungicide. Oranges absorbed more imazalil when treatment times were increased. Removal of the epicuticular wax from fruit before treatment with imazalil significantly reduced the control of sporulation of Penicillium digitatum and increased the rate of movement of the fungicide into the rind but did not significantly alter total residues.