Residues of the quinone outside inhibitor fungicide trifloxystrobin after postharvest dip treatments to control Penicillium spp. on citrus fruit.
The effectiveness of postharvest dip treatment with trifloxystrobin (TFX) or imazalil (IMZ) was compared for controlling green and blue mold (caused by Penicillium digitatum and Penicillium italicum, respectively) of citrus fruit. Residues retained by fruit were determined as a function of treatment time, dip temperature, and storage conditions. Trials on 'Avana apireno' mandarin oranges artificially inoculated with P. digitatum or P. italicum revealed that treatments with 200 to 600 mg/liter active ingredient TFX at 20 degrees C were less effective than 100 mg/liter TFX at 500C for controlling P. digitatum but equally effective for controlling P. italicum. IMZ treatments with 200 mg/liter IMZ at 20 degrees C or 25 mg/liter IMZ at 50 degrees C resulted in more than 98% reduction of P. digitatum and ca. 93% reduction of P. italicum compared with untreated fruit. Total suppression of pathogens was achieved when higher IMZ doses were applied. Studies on artificially wounded lemons, oranges, clementines, and mandarins revealed that treatment with 100 mg/liter TFX at 50 degrees C effectively controlled decay development (mainly due to P. digitatum) after 7 days of storage at 20 degrees C. These results were confirmed on nonwounded oranges of cv. Tarocco and on grapefruits of cvs. Marsh Seedless and Star Ruby during 3 weeks of simulated quarantine at 1 degrees C, storage (5 weeks at 8 degrees C for oranges and 8 weeks at 11degrees C for grapefruits), and an additional 1 week of simulated marketing conditions at 20 degrees C. IMZ at 50 degrees C was highly effective for controlling decay during storage and the simulated marketing period. TFX treatment at 50 degrees C was as effective as IMZ for controlling decay in most samples. After treatment with 100 mg/liter TFX at 20 degrees C, fungicide residues in 'Tarocco' oranges doubled from 0.15 mg/kg to 0.30 mg/kg when dip time increased from 0.5 to 3 min, whereas when treatments were performed at 50 degrees C TFX residues were not related to dipping time. Residues of TFX were significantly correlated with dip temperature. A 3-min dip treatment at 50 degrees C resulted in a deposition of TFX that was approximately twofold higher than that obtained when treatments were carried out at 20 degrees C.
Schirra
Mario
M
Consiglio Nazionale delle Ricerche, Istituto di Scienze delle Produzioni Alimentari, Sezione di Sassari, Via dei Mille 48, 07100 Sassari, Italy. mario.schirra@ispa.cnr.it
D'Aquino
Salvatore
S
Palma
Amedeo
A
Angioni
Alberto
A
Cabras
Paolo
P
Migheli
Quirico
Q
D000085:Acetates / Q000032:analysis / Q000494:pharmacology*; D002957:Citrus / Q000737:chemistry* / Q000382:microbiology; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D005511:Food Handling / Q000379:methods*; D005519:Food Preservation / Q000379:methods; D005659:Fungicides, Industrial / Q000032:analysis / Q000494:pharmacology*; D006801:Humans; D007093:Imidazoles / Q000032:analysis / Q000494:pharmacology; D007097:Imines / Q000032:analysis / Q000494:pharmacology*; D008689:Methacrylates / Q000032:analysis / Q000494:pharmacology; D010407:Penicillium / Q000187:drug effects* / Q000254:growth & development; D010573:Pesticide Residues / Q000032:analysis*; D000073739:Strobilurins; D013696:Temperature; D013997:Time Factors
D000085:Acetates; D005659:Fungicides, Industrial; D007093:Imidazoles; D007097:Imines; D008689:Methacrylates; D010573:Pesticide Residues; D000073739:Strobilurins; C017435:enilconazole; C467051:trifloxystrobin