Biocontrol Activity of Trichoderma Species Isolated from Grapevines in British Columbia against Botryosphaeria Dieback Fungal Pathogens

Abstract

Botryosphaeria dieback (BD) is a grapevine trunk disease (GTD) causing significant yield losses and limiting the lifespan of vineyards worldwide. Fungi responsible for BD infect grapevines primarily through pruning wounds, and thus pruning wound protection, using either synthetic chemicals or biological control agents (BCAs), is the main available management strategy. However, no products to control GTDs are currently registered in Canada. With a focus on more sustainable grapevine production, there is an increasing demand for alternatives to chemical products to manage GTDs. Accordingly, the objective of this study was to identify Trichoderma species from grapevines in British Columbia (BC) and evaluate their potential biocontrol activity against BD fungi Diplodia seriata and Neofusicoccum parvum. Phylogenetic analyses identified seven species, including T. asperelloides, T. atroviride, T. harzianum, T. koningii, T. tomentosum, and two novel species, T. canadense and T. viticola. In vitro dual culture antagonistic assays showed several isolates to inhibit fungal pathogen mycelial growth by up to 75%. In planta detached cane assays under controlled greenhouse conditions identified T. asperelloides, T. atroviride and T. canadense isolates from BC as providing 70% to 100% pruning wound protection against BD fungi for up to 21 days after treatment. In addition, these isolates were shown to provide similar or better control when compared against commercial chemical and biocontrol products. This study demonstrates the potential that locally sourced Trichoderma species can have for pruning wound protection against BD fungi, and further supports the evaluation of these isolates under natural field conditions.

Vineyard Management and Physicochemical Parameters of Soil Affect Native Trichoderma Populations, Sources of Biocontrol Agents against Phaeoacremonium minimum

“…Another study showed that after testing 16 Trichoderma isolates from Southern Italy, some of them protect grapevine plants against a great number of fungal pathogens that cause GTDs [ 27 ]. Moreover, native Trichoderma strains have been isolated from vineyards in British Columbia, Canada, as effective biocontrol agents against Botryosphaeria dieback [ 28 ]. In Spain, strains of T. harzianum had positive results after their application in young vine plants [ 29 ].…”

Holistic understanding of the response of grapevines to foliar application of seaweed extracts

“…The seaweed treatments did not result in a clear shift in the abundance of various known biocontrol agents, such as Trichoderma (Pollard-Flamand et al, 2022), Aureobasidium pullulans (Harm et al, 2011), Candida (Sipiczki, 2006), among others (Table 4). These organisms were found in general at low abundances in the analyzed samples and showed a high variability within treatment plant replicates.…”

Phytotoxic Metabolites Produced by Fungi Involved in Grapevine Trunk Diseases: Progress, Challenges, and Opportunities

“…However, only a limited number of fungicides are commercially available and registered to manage GTDs due to some of the effective fungicides, such as sodium arsenite and benzimidazoles, being removed from the market due to human and environmental safety concerns [ 2 ]. Biological controls such as Trichoderma -based products [ 12 , 13 , 14 , 15 ] for managing GTDs have increased in popularity, particularly for organic and biodynamic vineyards where synthetic chemicals are not an option.…”