In August 2020, anthracnose lesions were observed on fruits of Juglans regia and J. sigillata in walnut orchards, in Yijun (Shaanxi Province) and Nanhua (Yunnan Province) counties, China. Symptoms ...

English/Persian walnut (Juglans regia L.) is grown as an economically valuable crop in temperate and subtropical regions. In August of 2018, serious fruit anthracnose, with brown to black circular ...

Grafting is a traditional and significant strategy to suppress soil-borne diseases, such as the crown gall disease caused by tumorigenic Agrobacterium and Rhizobium. Root exudates and the rhizosphere microbiome play critical roles in controlling crown gall disease, but their roles in suppressing crown gall disease in grafted plants remain unclear. Here, disease-susceptible cherry rootstock ‘Gisela 6’ and disease-resistant cherry rootstock ‘Haiying 1’ were grafted onto each other or self-grafted. The effect of their root exudates on the soil microbiome composition and the abundance of pathogenic Agrobacterium were studied. Grafting onto the disease-resistant rootstock helped to reduce the abundance of pathogenic Agrobacterium, accompanied by altering root exudation, enriching potential beneficial bacteria, and changing soil function. Then, the composition of the root exudates from grafted plants was analyzed and the potential compounds responsible for decreasing pathogenic Agrobacterium abundance were identified. Based on quantitative measurement of the concentrations of the compounds and testing the impacts of supplied pure chemicals on abundance and chemotaxis of pathogenic Agrobacterium and potential beneficial bacteria, the decreased valine in root exudates of the plant grafted onto resistant rootstock was found to contribute to decreasing Agrobacterium abundance, enriching some potential beneficial bacteria and suppressing crown gall disease. This study provides insights into the mechanism whereby grafted plants suppress soil-borne disease.

Root exudates play a critical role in root–microbe interactions. Agrobacterium tumefaciens causes crown gall disease in multiple plant species, but rose root exudate-mediated inhibition of Agrobacterium in the rhizosphere is poorly understood. In this study, the influence of preinoculation with beneficial bacteria or pathogens on root exudates and subsequent colonization by A. tumefaciens was investigated in a split-root system. We found that preinoculation of rose plants in a split-root system with Bacillus velezensis CLA178 or A. tumefaciens C58 inhibited subsequent colonization by C58. Root secretion of valine had positive effects on the chemotaxis, biofilm formation, colonization of C58, and crown gall disease severity, but valine secretion decreased significantly when Rosa multiflora plants were preinoculated with CLA178 or C58. These results indicated that rose plants reduced root secretion of valine in response to microbial colonization, thereby reducing the colonization of Agrobacterium colonization and disease severity. This study provides new insights into the root exudate-mediated interactions of rose plants, B. velezensis, and A. tumefaciens and proposes a potential way to control crown gall disease.

Plant anthracnose, caused by Colletotrichum spp., is a class of significant diseases that severely threatens global crop production. Traditional management strategies, including chemical control, are hindered by inherent limitations such as the frequent emergence of pathogen resistance, low pesticide utilization efficiency, high environmental residue risks, and inconsistent field efficacy. Moreover, achieving further improvements in control efficacy is constrained by the complex biological characteristics of Colletotrichum species, particularly their hemibiotrophic lifestyle and latent infection strategies. In recent years, nanotechnology has emerged as a potential approach for the management of anthracnose. This review summarizes the research progress of various nanomaterials in the control of plant anthracnose. It analyzes the proposed multi-mechanism modes of action of nanomaterials tailored to the specific infection traits of Colletotrichum. Particular emphasis is placed on analyzing the theoretical mechanisms and preliminary in vitro evidence of nano-enabled controlled-release systems in addressing asymptomatic latent infections and achieving targeted, precise delivery. However, it must be emphasized that most current findings are derived from laboratory or controlled-environment studies, and the actual field-scale effectiveness, long-term environmental behavior, and multi-trophic safety of many nanomaterials remain insufficiently confirmed. Building upon these insights, this review thoroughly evaluates the critical challenges facing the agricultural field application of nanomaterials, such as ecotoxicity, formulation stability, scalable industrial production, and regulatory gaps. This review aims to provide objective theoretical support and technical references for achieving safe, efficient, and sustainable nano-enabled green management of plant anthracnose.