Control of lemon green mold caused by an imazalil-resistant Penicillium digitatum isolate

CERIONI LUCIANA; RAPISARDA, VIVIANA A.; PRADO, FERNANDO E.; RODRIGUEZ MONTELONGO, LUISA

Cordoba Argentina

Congreso; XLIV Reunión Anual SAIB; 2008

SAIB

Penicillium digitatum is the causal agent of citrus green mold. To avoid this pathogen, lemons have been treated with fungicides (mainly imazalil), leading to the proliferation of resistant strains and an increase of the toxic residues in the fruit. International markets have implemented strict limits on fungicide residues and thus, is urgent to find alternative methods for decay control. We standardized, in vitro, an oxidative sequential treatment (OST) at 20ºC, which consists in a pre-incubation with NaClO, followed by a incubation with H2O2 and CuSO4. Here, we analyze if the OST and some variations of it are effective on an imazalil resistant isolate. The effect of the treatment on the conidia was checked in vitro by viability on plate and infectivity on lemon fruit. The decay control was evaluated by application in situ of OST, in lemons inoculated (24 h before) with non-treated conidia. The results showed that the OST was effective against imazalil-resistant isolate. The protocol of OST was improved by incubation at 42ºC. Moreover the decay was significantly delayed in the fruits subjected to the oxidative treatment in comparison with those tried with water. Our OST may have a potential application for postharvest disease control of citrus fruits, and their applications at 42ºC would be suitable since this temperature activate the natural defense of fruit.