Fungal trunk diseases are some of the most destructive diseases of grapevine in all grape growing areas of the world. Management of GTDs has been intensively studied for decades with some great advances made in our understanding of the causal pathogens, their epidemiology, impact, and control. However, due to the breadth and complexity of the problem, no single effective control measure has been developed. Management of GTD must be holistic and integrated, with an interdisciplinary approach conducted in both nurseries and vineyards that integrates plant pathology, agronomy, viticulture, microbiology, epidemiology, biochemistry, physiology, and genetics. In this review, we identify a number of areas of future prospect for effective management of GTDs worldwide, which, if addressed, will provide a positive outlook on the longevity of vineyards in the future.

https://apsjournals.apsnet.org/doi/pdf/10.1094/PDIS-04-17-0512-FE

Managing Grapevine Trunk Diseases With Respect to Etiology and Epidemiology: Current Strategies and Future Prospects

In agricultural and natural systems researchers have demonstrated large effects of plant–soil feedback (PSF) on plant growth. However, the concepts and approaches used in these two types of systems have developed, for the most part, independently. Here, we present a conceptual framework that integrates knowledge and approaches from these two contrasting systems. We use this integrated framework to demonstrate (i) how knowledge from complex natural systems can be used to increase agricultural resource-use efficiency and productivity and (ii) how research in agricultural systems can be used to test hypotheses and approaches developed in natural systems. Using this framework, we discuss avenues for new research toward an ecologically sustainable and climate-smart future.

/pdf/plant-soil-feedback-bridging-natural-and-agricultural-rq6u9hu589.pdf

Plant–Soil Feedback: Bridging Natural and Agricultural Sciences

Cover cropping is a promising sustainable agricultural method with the potential to enhance soil health and mitigate consequences of soil degradation. Because cover cropping can form an agroecosystem distinct from that of bare fallow, the soil microbiome is hypothesized to respond to the altered environmental circumstances. Despite the growing number of primary literature sources investigating the relationship between cover cropping and the soil microbiome, there has not been a quantitative research synthesis that is sufficiently comprehensive and specific to this relationship. We conducted a meta-analysis by compiling the results of 60 relevant studies reporting cover cropping effects on soil microbial properties to estimate global effect sizes and explore the current landscape of this topic. Overall, cover cropping significantly increased parameters of soil microbial abundance, activity, and diversity by 27%, 22%, and 2.5% respectively, compared to those of bare fallow. Moreover, cover cropping effect sizes varied by agricultural covariates like cover crop termination or tillage methods. Notably, cover cropping effects were less pronounced under conditions like continental climate, chemical cover crop termination, and conservation tillage. This meta-analysis showed that the soil microbiome can become more robust under cover cropping when properly managed with other agricultural practices. However, more primary research is still needed to control between-study heterogeneity and to more elaborately assess the relationships between cover cropping and the soil microbiome.

Do cover crops benefit soil microbiome? A meta-analysis of current research

Ecological-economic trade-offs of Diversified Farming Systems - A review

Phaeoacremonium: From esca disease to phaeohyphomycosis

Commercial perennial agriculture is prone to declining productivity due to negative plant-soil feedback. An alternative to costly and environmentally harmful conventional treatment such as soil fumigation could be to manipulate soil microbial diversity through careful selection and management of cover crop mixtures. Although cover crops are already used in these systems for other reasons, their capacity to influence soil biota is unexploited. Here, we examine the role of plant diversity and identity on plant-soil feedbacks in the context of perennial agriculture. We identify key microorganisms involved in these feedbacks and explore plant-based strategies for mitigating decline of perennial crop plants. We conclude that (1) increasing plant diversity increases soil microbial diversity, minimizing the proliferation of soil-borne pathogens; (2) populations of beneficial microbes can be increased by increasing plant functional group richness, e.g., legumes, C4 grasses, C3 grasses, and non-leguminous forbs; (3) brassicas suppress fungal pathogens and promote disease-suppressive bacteria; (4) native plants may further promote beneficial soil microbiota; and (5) frequent tillage, herbicide use, and copper fungicides can harm populations of beneficial microbes and, in some cases, contribute to greater crop decline. Non-crop vegetation management is a viable and cost-effective means of minimizing crop decline in perennial monocultures but is in need of more direct experimental investigation in perennial agroecosystems.

/pdf/cover-crops-to-increase-soil-microbial-diversity-and-2h5lnlcnc8.pdf

Cover crops to increase soil microbial diversity and mitigate decline in perennial agriculture. A review

Young vine decline (YVD) is a complex disease caused by at least 51 different fungi and responsible for important economic losses to the grapevine industry worldwide. YVD fungi are known to occur in planting material. Hence, detection prior to planting is critical to assure longevity of newly established vineyards. A DNA macroarray based on reverse dot-blot hybridization containing 102 oligonucleotides complementary to portions of the β-tubulin region was developed for detection of YVD fungi. Specificity of the array was first evaluated against 138 pure fungal cultures representing 72 different taxa from nine genera, including 37 YVD species. In total, 61 species, including 34 YVD pathogens, were detected and identified by the array. The detection limit of the array was below 0.1 pg of genomic DNA. The array was validated against artificially inoculated canes and soil and commercial planting material, with the latter showing a high incidence of YVD fungi in nursery plants otherwise not detected by traditional plating and culturing. This DNA array proved to be a rapid and specific tool to simultaneously detect and identify most YVD fungi in a single test, which has the potential to be used in commercial diagnostics or by the grapevine nursery industry to determine the health status of the planting material.

https://apsjournals.apsnet.org/doi/pdf/10.1094/PHYTO-03-15-0069-R

Development of a DNA Macroarray for the Detection and Identification of Fungal Pathogens Causing Decline of Young Grapevines.

https://www.agrireseau.net/documents/Document_88779.pdf

Occurrence of phytoplasmas in leafhoppers and cultivated grapevines in Canada

Wine grape production is an important economic asset in many nations; however, a significant proportion of vines succumb to grapevine trunk pathogens, reducing yields and causing economic losses. Cover crops, plants that are grown in addition to main crops in order to maintain and enhance soil composition, may also serve as a line of defense against these fungal pathogens by producing volatile root exudates and/or harboring suppressive microbes. We tested whether cover crop diversity reduced disease symptoms and pathogen abundance. In two greenhouse experiments, we inoculated soil with a 106 conidia suspension of Ilyonectria liriodendri, a pathogenic fungus, then conditioned soil with cover crops for several months to investigate changes in pathogen abundance and fungal communities. After removal of cover crops, Chardonnay cuttings were grown in the same soil to assess disease symptoms. When grown alone, white mustard was the only cover crop associated with reductions in necrotic root damage and abundance of Ilyonectria. The suppressive effects of white mustard largely disappeared when paired with other cover crops. In this study, plant identity was more important than diversity when controlling for fungal pathogens in vineyards. This research aligns with other literature describing the suppressive potential of white mustard in vineyards.

/pdf/cover-crop-diversity-as-a-tool-to-mitigate-vine-decline-and-2qoss8ktju.pdf

Tom Lowery

Papers

Cover crops to increase soil microbial diversity and mitigate decline in perennial agriculture. A review

Development of a DNA Macroarray for the Detection and Identification of Fungal Pathogens Causing Decline of Young Grapevines.

Occurrence of phytoplasmas in leafhoppers and cultivated grapevines in Canada

Cover Crop Diversity as a Tool to Mitigate Vine Decline and Reduce Pathogens in Vineyard Soils

First Report of Grapevine Pinot gris virus in British Columbia, Canada