Exploring eco-friendly strategies for the management of blue mold of apple caused by Penicillium crustosum thom

Abstract

Blue mold disease, incited by Penicillium sp is an important post-harvest disease of apple adversely affecting their quality. The present study showed about ten percent of the fruit were affected by this disease. The causative organism of blue mold was isolated and identified as Penicillium crustosum Thom using morphological characteristics, molecular analysis (including Beta-tubulin, LSU, and ITS gene sequences), and pathogenicity tests. Following identification, green strategies such as essential oils (Eos, 8 nos) and biocontrol agents (BCAs, 6 nos) were evaluated to manage the disease. Initially, these green chemicals were assessed using the poisoned food technique. Among the eight EOs tested, Ocimum tenuiflorum L. and O. sanctum L. were selected for further studies as they showed > 90 percent inhibition of mycelial growth at all tested concentrations. In the sandwich method assay, O. sanctum demonstrated 95 % inhibition at a 0.5 % concentration and achieved 100 % inhibition at 1.0 % concentration, outperforming O. tenuiflorum which showed 93.3 % and 95.0 % inhibition at 0.5 % and 1.0 % concentration, respectively. Among BCAs (Trichoderma spp.) the inhibition of P. crustosum growth varied significantly, T. longibrachiatum (isolate 2) showed the highest mycelial growth inhibition (83.15 %) therefore selected for further studies. The most effective treatments, identified through in vitro experiments, when tested on apple fruit, the use of spray treatment of 0.5 % O. tenuiflorum EO or fumigation treatments of 1 % O. sanctum EO, gave more protection therefore recommended for management of blue mold of apple. Based on available information, this appears to be the first documented case of apple blue mold caused by P. crustosum in India, along with attempts at its ecofriendly management.