The Effect of Several Chemicals and Fungicidal Waxes on Decay Control in Loose-Skinned Oranges

Several chemicals, namely, borax and boric acid Dowicide A, Thiabendazele (TBZ). and Benlate (D-199l) were tested separately in water solution and wax emulsion for control of penicillium mold decay in loose-skinned oranges. The oranges were scratc-inoculated with mold spores and incubated at 68°F for 0, 12, 18, 24, 36, and 48 hours before fungicidal treatment The inuculation process was carried out by means of a smear with a Chinese writing brush dipped in a concentrate spate suspension (approximately 1-1.5 mil-lion per c. c.) The teat oranges were held at 68°F and 85-90% r. h. for 3 weeks and inspected for decay at intervals of 3, 7, 14, and 21 days after treatment The late-season Ponkan oranges have a higher rate of decay than the mid-season oranges due to a lower vitality. Bath TBZ and Benlate showed a long or antifungal function on mold control than borax-boric acid and Dowicide A and seemed to have a higher fugistat effect on germination of mold spares having effective decay control at the concentration of 250ppm and no peel injury at 2000ppm. TBZ and Benlate in water solution and in wax emulsion were equally effective. However, Fresher water-wax (a commercial wax) alone was not effective to control citron decay. TBZ and Benlate of l000ppm controlled decay in the Ponkan oranges incubated or 24 hrs. With Tankan oranges, TBZ controlled decay in the fruit incubated for 24 hrs while Benlate was only effective in the fruit incubated for 18 hrs. Thus, we would recommend to treat Ponkaw with TBZ or Benlate within 24 hrs after the possible infection has occurred, and Tankan within 18 hrs.