Field Efficacy of Antagonistic Fungi against Black Spot Disease of Chinese Kale

Abstract

Background: Alternaria brassicicola (Schw.) causes black spot disease, which is one of the major diseases limiting the production of vegetable crops, especially Chinese kale in Southeast Asia and Thailand. Previous pathogen management based on synthetic fungicides is expensive, toxic for humans and harmful to the environment. The current study investigated the efficiency of Talaromyces flavus (Klöcker) Stolk and Samson Bodhi001, Talaromyces trachyspermus (Shear) Stolk and Samson Bodhi002, Talaromyces flavus (Klöcker) Stolk and Samson Bodhi003, Neosartorya fischeri (Wehmer) Malloch and Cain Bodhi004 and Neosartorya fischeri (Wehmer) Malloch and Cain in controlling Chinese kale black spot disease caused by A. brassicicola under field conditions. Methods: A. brassicicola and four antagonistic fungal strains were cultured separately on a PDA plate and incubated at room temperature for 14 days. Ten mL of sterile water was poured into a culture plate and the spores were gently scraped from the mycelium with a sterile loop to obtain a spore suspension and afterwards adjusted to a final concentration of 106 spores mL-1. Result: The results showed that spore suspensions of 106 spores mL-1 of T. flavus Bodhi001, T. trachyspermus Bodhi002, T. flavus Bodhi003, N. fischeri Bodhi004 and N. fischeri effectively controlled black spot disease in field trials and resulted in a significant reduction in black spot incidence compared with the unprotected control. Meanwhile, the spore suspension of T. flavus Bodhi001 revealed the greatest suppression of black spot incidence, causing 10.23% and 42.93% disease reduction, compared with the negative control, indicating promising preventive activity against A. brassicicola. Based on our results, T. favus Bodhi001 is a promising biological control agent (BCA) in controlling A. brassicicola causing Chinese kale black spot disease.