Effectiveness Of Fungicide Application Systems In The Control Of Penicillium Digitatum In Oranges In Tucuman Argentina

Abstract

The citrus green mold caused by Penicillium digitatum produced the main postharvest decay and its control depends on fungicides application. At the present a rotating spray system is used in the packing for fungicide application. The aim of this work was to compare the effectiveness of the rotating spray (rss) and immersion systems (is) for fungi control, measuring the residual active ingredients (rai) in fruits. Orange fruits were inoculated using a punch previously dipped in a spore suspension and stored for 24h at 20ºC and 90% RH. Then fruits received the following treatments: T1 water (control), T2 0.16% IMZ+PRM applied with rss at the packing line, T3 wax+0.2% IMZ with rss at the packing line, T4 dipping in 0.16% IMZ+PRM for 30 seconds, T5 dipping in wax+0.2% IMZl for 30 seconds. Fruits were stored at 4ºC and 90% RH during 15d and then at 20ºC and 90% HR during 7d. Fruit damages were evaluated as % of control (incidence). The residual active ingredients (rai) residue levels were measured in fruit, flesh and essential oil. Results indicated that the best treatment was T4 with 100% control capacity. The rai in fruit were: 2 mg/kg of PRM and 3.8 mg/kg of IMZ, and in essential oil: 104mg/kg of PRMl and 182mg/kg of IMZ. T2 treatment yielded 30 % of control and the rai in fruit were: 1.2mg/kg of PRM and 0.69mg/kg of IMZ and in essential oil: 89mg/kg of PRM and 37mg/kg of IMZ. No residue was de-tected in the flesh. The effectiveness of application system was directly related to the rai level found in fruits and essential oil.