Seven irradiation tests (with exposures of 0, 7.5, 15, 30, 60 and 90 krad) were conducted on 26 lots of grapefruit throughout the 1981–82 and early 1982–83 citrus seasons. Fruit treated with 60 and 90 krad showed rind breakdown and scald after storage for 28 days at optimum temperatures. Scald was the dominant injury in early-season fruit in tests conducted during Oct. and Dec. 1981 and Sept, and Oct. 1982. Rind breakdown, especially pitting, was the dominant injury in all other tests with midseason and late-season fruit. At the 7.5-, and 15-, and 30-krad exposures, injury was minimal, and fruit exposed to these dosages were acceptable. Although some 60- and 90-krad exposures resulted in excessive injury, 2 tests at 60 and 90 krad were acceptable with early fruit. In some instances, injured areas developed decay after storage and marketing conditions at 21°C.
Research Entomologist, Plant Introduction Station, ARS, USDA, Miami, FL 33158.
Mathematical Statistician, ARS, USDA, Univ. of Florida, Gainesville, FL 32611.
Received for publication 6 Jan. 1984. Mention of a trademark, warranty proprietary product, vendor or pesticide/herbicide in this paper does not constitute a recommendation for use by the USDA to the exclusion of other products or vendors that may also be suitable, nor does it imply registration under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) as amended. We wish to express our appreciation to the Fla. Dept. of Citrus for its interest and support in this research. We acknowledge the technical assistance of W.J. Whitfield and J.D. Pierce, Sandia National Laboratories, Albuquerque, N.M., for the irradiation of the fruit and the verification of the dosimetry. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.