Antifungal Potential of Biocontrol Agents against Penicillium georgiense Causing Onion Mold in Pakistan

Onion is an important vegetable crop prone to many abiotic and biotic stresses. The blue mold rot of onion caused by Penicillium georgiense ( P. georgiense) is one of the most damaging diseases in Pakistan and worldwide. The current study includes the factors that are responsible for losses at a considerable level where onion is being grown, transported, and stored. This study represents the first comprehensive integration of morphological and molecular identification of P. georgiense . Standard tissue isolation and polymerase chain reaction (PCR) techniques were used for morphological and molecular characterization of the pathogen, respectively. Microscopic examination revealed that short-chain, ellipsoidal to subspheroidal conidia, similar to the morphological characters of P. georgiense . Results of PCR amplification of the Internal Transcribed Spacer (ITS) and further confirmation with sequencing showed 97–99% similarity to the P. georgiense species complex. Different biocontrol agents (BCAs) were evaluated against P. georgiense under in vitro conditions. In vitro findings exhibited that Trichoderma sp. biocontrol agent expressed efficient results with maximum effectiveness against radial colony growth of the test fungus, whereas the mean radial colony growth was recorded as 37 mm over the control (90 mm). Moreover, the effectiveness of Paecilomyces lilacinus ( P. lilacinus ) followed by Bacillus subtilis ( B. subtilis ) was also significant in reducing the radial growth of the test fungus, and means were recorded as 59 and 67.67 mm, respectively. Based on these findings, P. georgiense was identified morphologically and molecularly as the prevailing pathogen at all locations as casual agent of blue mold of onion. Moreover, the Trichoderma sp. emerged as effiecient antifungal potential against P. georgiense , followed by P. lilacinus and B. subtilis . Hence, their potential was found promising to control the test fungus.