Developing sustainable peach orchard soil microbiome management practices to control replant disease syndrome

View the project final report

Commodities

• Fruits: peaches

Practices

• Crop Production: cover crops, crop improvement and selection, crop rotation, cropping systems, tissue analysis, varieties and cultivars
• Education and Training: demonstration, extension, on-farm/ranch research, workshop
• Pest Management: biological control, competition, cultural control, soil solarization
• Production Systems: integrated crop and livestock systems, organic agriculture
• Soil Management: soil analysis, soil microbiology, soil quality/health

Colorado peaches (Prunus persica) are an important specialty crop with excellent market acceptance and superior quality due to the unique growing conditions. Orchard replant disease (RD) is a soil-borne disease that affects young trees planted in sites where the same or closely related species were previously grown. RD has become a major production problem of the Colorado and Intermountain peach industry primarily due to the limited amount of land suitable to grow tree fruit crops. Annual losses in yield and orchard longevity due to RD are estimated to reach as much as 20%. Factors implicated in RD etiology in other crops include mainly soil pathogens (bacteria, fungi, oomycetes, nematodes) and phytotoxicity from allelopathic toxins in plant roots. However, in peach the biological component that causes RD remains largely unknown. Conventional management strategies have relied on broad-spectrum fumigants such as methyl bromide, which was phased-out due to environmental concerns. The lack of effective alternatives to control RD in conventional and organic stone fruit production systems, create an urgent need for environmentally sound and sustainable RD-management solutions. Herein we propose a research-extension-producer team approach to understand peach RD etiology, evaluate sustainable alternative strategies to manage this disease and impact farmer decision-making by sharing results and end products through multiple methods. Alternative strategies to be tested in greenhouse, agricultural experimental stations and multi-state on-farm trials in organic and conventional commercial orchards include cover crops, short-term crop rotation, use of RD-tolerant peach rootstocks and plant growth promoting rhizobacteria (PGPRs), which can be used as beneficial microbial components that mitigate RD symptoms in commercial orchard systems. Our overall goal is to provide peach growers located in challenging climates with a bio-intensive orchard RD management strategy. A combined physiological and molecular approach is expected to shed some light on the etiology of peach RD development. High-throughput molecular techniques combined with physiological measurements will identify pathogenic microbiomes related with RD symptoms on susceptible rootstocks; which can allow for effective management decisions from a biological stand point. Our proposed approach is also expected to generate information on the role of many other beneficial microbiomes that can mitigate RD stress and promote tree growth. Through this bottom-up research and extension/outreach approach we will generate solid information on RD etiology and sustainable management strategies for conventional and organic peach production systems to improve soil health, and increase orchard productivity, longevity and grower profitability.

This project will bring together university and USDA researchers, extension personnel and producers from three states (CO, UT, ID) together to develop best management solutions for RD in organic and conventional peach production systems under western Intermountain climatic conditions. The establishment of this research and education program will provide reliable RD control tools and a clearer understanding of the etiology of this disease to the stakeholders and scientific community.

The goal of this proposed project is to help improve the economic and environmental aspects of fruit production in Colorado and other western regions through sustainable and readily applicable peach orchard replant management solutions.

Our specific objectives (click: Figure 3) are to:

1. Evaluate the influence of PGPRs, cover and rotation crops on soil health and RD-mitigation on susceptible clonal peach seedlings in greenhouse conditions and on-farm
2. Identify RD-tolerant rootstocks and the soil microbiome changes associated with RD development/resistance in greenhouse and on-farm conditions
3. Impact farmer decision-making by sharing results through multiple methods