Potential Value of Wood Tar as a Natural Fungicide against Valsa mali

Abstract

The Valsa canker caused by Valsa mali seriously harmed the production of East Asian apples and caused very significant economic losses. Considering the chemical residues and the improvement of people’s awareness of environmental protection, there is a need for screening new green pesticides for the control of Valsa canker. Therefore, we conducted systematic evaluations on the antifungal activity of wood tar. In this research, the effective concentration (EC50) of six strains of V. mali to wood tar was determined, and the EC50 ranged from 69.54 to 92.81 μg/mL. After treatment with wood tar, the hyphae of V. mali broke, swelled, and deformed; the permeability of the cell membrane increased; and the activity of pectinase reduced. Moreover, the expression levels of five genes related to pectinase also decreased significantly. In addition, the activities of phenylalanine ammonia lyase (PAL) and peroxidase (POD) of apple leaves treated with wood tar also increased. On detached apple branches, wood tar also showed therapeutic and protective activities. In the 2016–2019 field experiments, wood tar also showed good efficacy against Valsa canker and promoted the formation of callus. (In the experiments from 2016 to 2019, it can be seen that the control effect of 50% wood tar and 100% wood tar in the field is above 75% and promoted the formation of callus.) This study is the first to report the bidirectional efficacy of wood tar against Valsa mali and for trunk wound healing. The above results evidenced that wood tar has great potential to be developed as a natural alternative to commercial fungicides for the management of apple Valsa canker.

Back to the origins: biopesticides as promising alternatives to conventional agrochemicals

“…The pathogenic fungus Valsa mali was affected by wood tar (EC 50 ranged from 69.54 to 92.81 μg/mL), leading to hyphal breaks, increased cell membrane permeability, and unbalanced enzyme production related to the decrease in pectinase and related genes. (Chen et al, 2022). A series of Michael-type amino derivatives were prepared from xanthatin, a secondary metabolite extract from Xanthium strumarium, with antifungal activity and inhibition of mycelium growth on C. mandshurica and spore germination against F. solani (Zhi et al, 2022).…”

Isolation of anthraquinone derivatives from Rubia cordifolia (Rubiaceae) and their bioactivities against plant pathogenic microorganisms

“…where C is the colony diameter of the negative control group, T is the colony diameter of the treatment group, and E is the mycelial colony diameter. The protective and curative effects of the extract of R. cordifolia L. and its extracts against apple Valsa canker and tomato grey mould were determined on excised apple twigs 27 and tomatoes. 28 The excised apple twigs and tomato fruits were wounded, and mycelial plugs were inoculated into the wound area.…”