Biocontrol of Penicillium sp producer of blue rot in stored apples

LAMBRESE, Y.; SANZ FERRAMOLA, M.; SANSONE, G.; CALVENTE, V.; CÁCERES, M.; YAMANOUCHI, M.P.

San Luis

Congreso; XXXIX Reunión Científica Anual de la Sociedad de Biología de Cuyo.; 2021

Sociedad de Biología de Cuyo

Penicillium is a filamentous fungus of which several species cause rot in fruits and vegetables, particularly Penicillium expansum can cause blue rot in stored apples. Synthetic fungicides are used as chemical treatment, but the existence of resistant strains that would require the use of larger amounts of these is recognized; biological control, using antagonist saprophytic microorganisms that effectively compete with the pathogen is a control alternative. The objective of the work was to study in Red delicious apples 3 Biological Control Agents (BCA) to control Penicillium sp resistant to commercial fungicides. The microorganisms used were Penicillium sp INTA 6 isolated from blue rot in the Alto Valle of Río Negro and the BCA: Cryptococcus laurentii, Rhodosporidium fluviale and Kosakonia radicincitans isolated from healthy apples fromMendoza and San Luis. Initially, the phytopathogen was selected among 13 strains of Penicillium sp, challenging them against 5 fungicides used in Argentina. Petri dishes with Potato Dextrose Agar (PDA) medium inoculated with a suspension of the fungus were used, then holes were made that were filled with each fungicide (CAPTAN50WP, TECTO®50SC, PENBOTEC®400SC, SCHOLAR®23SC, CARBENDAZIM50SC) at the dose used in postharvest treatments. The plateswere incubated at 25 ºC and Mycelium Growth Inhibition (cm) were determined at 3 and 7 days. The biocontrol tests were performed on commercial apples washed and then wounded to inoculate them with each BCA and/or pathogen. Apples were stored 10 days at 25°C and the diameter of the rots was measured (mm). The rot diameters (ø) of the control and treatment were measured and the results were expressed as % Disease Incidence (% DI: [(rotten wounds in treatment / rotten wounds in control] x100) and % Severity Reduction (% SR: [(ø control - ø treatment) / ø control] x100) at 5 and 10. At the end of the trial, all the rotten tissue (control and treatments) was removed, weighed on an analytical balance and % SR was calculated. Penicillium sp INTA 6 showed Mycelium Growth Inhibition with CAPTAN50WP (1.53 and 0.9 cm) and SCHOLAR®23SC (3.1 and 2.07) at 3 and 7 days respectively, but it was totally resistant to TECTO®50SC, PENBOTEC®400SC and CARBENDAZIM50SC at 7 days. In apples, the 3 BCA controlled blue rot. After 5 days % DI for C. laurentii and R. fluviale was 0 %, while for K. radicincitans it was 11 %. At 5 days, the % SR for C. laurentii and K. radicincitans were 79 % and R. fluviale of 80 %. At 10 days % SR increased when the yeasts (C. laurentii or R. fluviale) were applied, but for the bacteria (K. radicincitans) the % SR was maintained over time. Finally, the rotten tissue was weighed and the % SR for C. laurentiiwas 97 % and R. fluviale of 93 % and for K. radicincitans was 44 %. It is concluded that the implementation of BCA is a very good alternative to control Penicillium sp, resistant to fungicides and producer of blue rot in stored apples.