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

Progress report for SW20-910

Project Type: Research and Education
Funds awarded in 2020: $350,000.00
Projected End Date: 08/31/2023
Host Institution Award ID: G171-21-W7899
Grant Recipient: Colorado State University
Region: Western
State: Colorado
Principal Investigator:
Dr. Ioannis Minas
Colorado State University
Co-Investigators:
Dr. Jorge Vivanco
Colorado State University
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Project Information

Abstract:

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 a research-extension-producer team approach is implemented 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 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 sheds some light on the etiology of peach RD development. High-throughput molecular techniques combined with physiological measurements identified pathogenic microbiomes related with RD symptoms on susceptible rootstocks; which can allow for effective management decisions from a biological stand point. Our 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 generated 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.

Project Objectives:

This project brings 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 implementation of this research and education program provides reliable RD control tools and a clearer understanding of the etiology of this disease to the stakeholders and scientific community.

The goal of this 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
Timeline:

A timeline, in the form of a Gantt chart, for accomplishing each objective and identifying the major activities/milestones performance, duration and completion times is provided (click here: Gantt chart).

Cooperators

Click linked name(s) to expand/collapse or show everyone's info
  • Steve Ela - Producer
  • Daniel Manter (Researcher)
  • Jeff Rowley - Producer
  • David Sterle (Researcher)
  • Dr. Frank Stonaker (Researcher)
  • Bruce Talbott - Technical Advisor - Producer
  • Larry Traubel - Technical Advisor

Research

Hypothesis:

Replant disease is a global challenge induced upon intensive cultivation of perennial crops (Zhu et al., 2016). After replanting of an orchard, one common symptom of replant disease is poor root health and reduction in overall plant health (Mazzola et al., 2012). Although the specific etiology is not fully understood, it is known that the reduced crop productivity due to replant disease is caused by a complex of parasites/pathogens, microbial plant competitors and repeated plantings of closely related plant species (Mazzola et al., 2012). Monoculture reduces crop production upon repeated plantings (Mazzola et al., 2012 Zhu et al., 2016). This reduced crop production can also be caused by abiotic factors like decreased soil fertility, poor soil structure, and residual herbicide activity (Mazzola et al., 2012). However, there is more support for a biological component since replant disease can persist in fallowed soils for many years which is atypical for toxins (Mazzola et al., 2012). Further support of a biotic component was provided by soil pasteurization studies where trees grown in fumigated soils grew better than trees grown in non-fumigated soils (Mazzola et al., 2012). Thus, it seems that the soil and rhizosphere microbiome is directly linked to replant disease.

Microbes within the soil microbiome are highly connected, and disturbances of different kinds can affect microbial growth and functionalities (Smith et al., 2016). Soil disruption can be caused by over fertilization, tillage, crop rotation, cover crop practices, solarization and chemical fumigation (Li et al., 2019). Previous disease management of replant disease involved chemical fumigation of orchard soils before the planting of saplings (Zhu et al., 2016). In general, soil fumigation appears to be limited in its ability to suppress re-plant disease since its benefit of inducing a growth response in an orchard only lasts a year and the disease rebounds completely within two growing seasons (Wang et al., 2019). Furthermore, fumigation is no longer a viable option due to environmental restrictions placed on the fumigants (Zhu et al., 2016). Thus, other more sustainable strategies crop rotations and cover crops could be added as a part of the solution in dealing with orchard replant disease.

Known benefits of crop rotation are pest management, fertility, and crop yield (Peralta et al., 2018). Additionally, temporal crop biodiversity may encourage beneficial ecosystem functions such as pest control, carbon sequestration, and nutrient cycling. It was also found that for no crop (fallow) treatments, disease suppressive potential was greatly diminished compared to the more diverse crop rotation treatments (Peralta et al., 2018). However, neither crop rotation or fallowing methods are practical against orchard replant disease (Zhu et al., 2016). Even though the value of crop rotation is plain to both organic and conventional agriculturists, this tool alone cannot solve the issue of replant disease and is only a part of the solution.

Cover cropping is a sustainable agricultural technique defined as planting crops for a purpose other than harvest (MacLaren et al., 2019). Cover cropping can be used for soil preservation, nutrient restoration, and organic fertilizer through reincorporation (Altieri et al., 2015). Since cover crops affect the chemical and physical properties of the soil, the biological properties of the rhizosphere also change (Peralta et al., 2018). The rhizosphere is the narrow region of soil where plant-microbial symbioses occur between the soil microbiomes (which contains a multitude of bacteria and fungi) and the plant’s roots (Hao e al., 2016). Plant-microbial symbioses within the rhizosphere can potentially improve soil fertility and degrade toxic nutrients (Hrynkiewicz, K., and Baum, C. 2012). Furthermore, symbioses in the rhizosphere can influence pathogen populations (Peralta et al., 2018).

Use of replant disease-tolerant rootstocks is a valuable alternative to soil fumigation for apples. However, research on peach rootstocks is ongoing and has yet to provide effective replant disease-tolerance without affecting tree vigor, acclimation/cold hardiness and fruit quality (Minas et al., 2018). Excessive tree vigor that promotes heavier pruning practices or cold damage susceptibility can provide more ports of entry for tree canker pathogens. Thus, for a resilient conventional and organic replant disease control solution in challenging climates, rootstock evaluation is critical to be done locally to ensure that replant disease-tolerant rootstocks are adapted to the environment.

In this study, we planted corn, tomato, alfalfa, and fescue to be used as cover crops in disrupted and non-disrupted soils. We disrupted the soil using a steam autoclave for three cycles of 40 minutes. After 12 weeks we reincorporated the cover crops and planted replant disease susceptible peaches. In addition to the cover crops a list of Prunus app. rootstock genotypes of variable vigor where tested under greenhouse conditions in disrupted and non-disrupted soils.

Materials and methods:

Soil Disruption  

Soil for the experiment was acquired from Colorado State University's Experimental Orchard at Western Colorado Research Center in Orchard Mesa, CO. This research center’s peach orchard was established 14 years ago using ‘Lovell’ rootstock peach trees and it’s soil exhibits symptoms of peach replant disease. Replant diseased soil was transported to Colorado State University's Horticultural Center Greenhouse facility in coolers. In the Horticultural Center, the soil was passed through a metal sieve (2cm wide) to remove large rocks and debris. The soil was then homogenized and separated into two equal parts.

For soil disruption, one half of the soil was double bagged in 24” x 30” polyethylene autoclave bags and autoclaved in a STERIS brand steam autoclave for three 40-min liquid cycles at 121 °C. In between autoclave cycles, bagged soils were rotated and shaken. Soil samples of the replant soil were collected before and after sterilization and stored in −80 °C to be used as controls in microbiome analysis.

One-gallon black plastic pots (n=100) were scrubbed with Alconox detergent, rinsed with tap water, and left to dry. After the plastic pots were dry, these were sprayed with 3% bleach (NaOCl) and rinsed with 70% isopropyl alcohol using a spray bottle. To attain consistent drainage and to mitigate runoff, the bottom of the pots was lined with Vigoro Weed Control Fabric Medium Duty (circle cutouts with 20cm diameter) and then placed on Vigoro 6 inch Plastic Plant Saucers. Pots were then filled with untreated replant diseased soil (n=50) and autoclaved replant diseased soil (n=50) just below 5 cm of the lip of the pot. Each pot contained ~2.1 kg of soil.

Cover Crop Seed Density and Sterilization

Four cover crops were selected for this study, ranger alfalfa (Medicago sativa), Natural Sweet F1 OG Hybrid Bicolor Sh2 corn (Zea mays), hybrid cherry tomato SUN Gold F1 (Solanum lycopersicum), and a fescue mix (Festuca: Chewing fescue, hard fescue, creeping red fescue). Seed density per plastic pot was calculated by using crop seed weight per square feet currently practiced in agriculture (put a reference), and then by measuring the surface area of each 1-gallon pot. Each 1-gallon pot had 0.239 square feet of surface area. For corn and tomato plants, only a single plant was used in each pot. For a fescue mix of two or three species, it is recommended to use 3 to 5 pounds of seed per 1,000 square feet (Fresenburg et al., 2005). For this study, 5 lbs. per 1000 square feet was used to calculate 0.542 grams of fescue seeds per pot (~529 fescue seeds). It is recommended to use 75 seeds of alfalfa per square foot, of which 45 seeds survive after the following four weeks (Rankin et al., 2008). For this study, 0.038 grams of alfalfa seeds was used per pot (~21 alfalfa seeds).

For seed sterilization, 15 ml falcon tubes with seeds were filled with 3% NaOCl and vortexed at max speed for one minute. Using a pipette, the NaOCl solution was then aspirated out. Seeds were then rinsed with autoclaved distilled water, vortexed at max speed for one minute, and then using a pipette the water was removed (repeated 5x). After the final water rinse, seeds were immediately planted into the soil and evenly dispersed using heat sterilized tweezers. To ensure the germination of at least one seed, corn and tomato treatments had three seeds planted in each pot with smaller or non-germinated seeds being removed after five days. Each cover crop treatment was planted in autoclaved soil (n=10 per cover crop) and untreated soil (n=10 per cover crop). Non-disrupted pots were used as a control for the soil disruption treatment. Pots with no cover crops growing in disrupted and non-disrupted soils were used as a control for the cover crop experiment. Pots without cover crop plants were started at the same time as the cover crops and were watered daily just like the pots with plants for the length of the experiment.

Cover Crop Greenhouse Experiment

Pots (n=100) were then set in a random block design using an online random block design generator (Research Randomizer program at https://www.randomizer.org). This generator ensured that there was one treatment per row. After the first week growing in the greenhouse, additional seeds were added to the pots based on seed count. All pots were watered ~200 ml, six days a week for 12 weeks.

After 12 weeks, the height of all cover crops was measured. Using scissors, the above ground cover crop biomass was cut into <2 cm pieces. Fresh above ground biomass of the cover crops was then recorded (only fresh biomass was recorded since the cover crop was immediately reincorporated into the soil to mimic cover crop agricultural practices). After a pot was processed, scissors used on the cover crop sample were washed in 3% NaOCl followed by heat sterilization using a bacti-cinerator. The fresh above ground biomass of the cover crops was then reincorporated into the soil within the first 3 cm of the same 1-gallon pot where the crops had grown in.  Cover crops were left to decompose for two weeks before peach planting.

Peach ‘Lovell’ rootstock cultivar was grown from seeds in liners using Pro-Mix potting media in a greenhouse for 28 days. This cultivar was selected since it is known to be replant disease susceptible and was the cultivar that was grown in the orchard where the replant diseased soil was collected. These four-week-old peach samplings were then randomly transplanted into the pots which previously had cover crops and no cover crop controls. Peach trees were watered daily with ~150 ml. Every two weeks, the height and diameter of the peach saplings were measured with a digital caliper. At two points in the study, peach leaf health was visually determined by categorizing the number of leaves as either “healthy” or “unhealthy” based on color and leaf spotting. Residual weeds and cover crops were continuously removed, and no fertilizer was added to the trees as to minimize interference with the soil microbiome. Peaches were grown for 22 weeks.

For microbial analysis, bulk soil, rhizosphere soil, and peach roots were collected. Bulk soil samples were collected from the top 7cm of soil within 2 cm of the base of the tree trunk and immediately stored in -20°C. After the removal of most of the soil, soil that still clung to the roots was removed and placed into 15 ml falcon tubes and stored in -20°Cimmediately after the sample was taken for later rhizosphere analysis. Here, the rhizosphere is defined as the 0–4 mm of soil adhering to the roots after the gentle removal of bulk soil and shaking the root system by hand. For root endophytic analysis, 0.5 grams of the longest and healthiest root was placed into 1.5 ml microcentrifuge tubes an immediately stored in -20°C. Root systems were then washed in tap water baths to remove all soil. Above ground biomass was separated from below ground biomass and weighed to record fresh biomass. Fresh biomass samples were placed into paper bags and then a drying oven at 90°C. After 72 hours, samples were weighed for dry above and below ground biomass. Samples where then stored at room temperature in paper bags for possible nutrient analysis.

Rootstock Greenhouse Experiment

For the rootstock genotype experiment, the growth of 7 Prunus spp. rootstocks of variable vigor ('Hansen 536', 'Trio-2507', 'Trio-2207', 'Krymsk86', 'MP-29', 'RootPac20', and Controller6) were compared to RD susceptible 'Lovell' trees in disrupted and non-disrupted RD soil as described above for the cover crop experiment.

Soil Analysis

Soil analysis (total nutrient digest and Haney H2O extract) was performed by WARD Laboratories, Inc. Total nutrient digest analysis quantifies the total values of elements in a soil, which includes nutrient pools that are available or unavailable to the plant (C, N, P, K, Ca, Mn, S, Zn, Fe, Mg, Cu,
B, Mo). Haney H2O extract analysis quantifies nutrients within the soil that are available to soil microorganisms (soil respiration, water-soluble organic C, N, and C/N). Three bulk soil samples were selected per treatment.

DNA Extraction

Total genomic DNA (gDNA) was extracted from 0.25 ± # g of soil in a QIAcube instrument (Qiagen, Germantown, Maryland) using PowerSoil ® DNA kits by Qiagen. All DNA extractions were preformed according to Qiagen’s instructions with a final elution volume of 100 μl. The concentration of DNA extractions was quantified using a Qubit with broad range assay solutions, before being stored at −80 °C until library preparation and sequencing. All ten cover crop replicates were extracted, with samples being pooled in pairs for a total of five replicates per treatment. Bulk soil samples taken at three different time points of right before cover crop reincorporation, two weeks after reincorporation, and after growing peaches. Peach rhizosphere replicates were also pooled by pairs, for five replicates for each treatment for extraction. The controls used were pre-extracted Zymo gDNA (Zymo Research Corporation, CA, USA) (n=4), HPLC water (n=4), stock soil (n=4), non-disrupted soil (n=5), and disrupted soil (n=5). In total, 182 samples were extracted.

Oxford Nanopore Library Prep, Sequencing, and Bioinformatics Pipeline

Extracted DNA and barcodes was suspended in AMPure bead solution in a 96 well plate. Beads with DNA attached, were removed using a magnetic rack. DNA which had adhered to the beads was washed by 70% ethanol. After sitting in the ethanol wash for 30 seconds, the bead rack was removed and left to dry. This ethanol wash was repeated. DNA was resuspended in a 96 well plate with PCR grade water. The well plate was then placed into a vortex shaker for 10 minutes. All 96 wells of suspended DNA was then pooled into a clean Lo-Bind tube. The MinION sequencer used a flow cell (R9.4.1) and was prepared for DNA was loading. To prepare the flow cell, air (~20 µL) was removed using a pipette. The flow cell was then primed with flush buffer (ONT, 200 µL), followed by the addition of the pooled DNA (200 µL) into the sample loading port. Sequencing was initiated via MinKNOW software and continued for the next 48 hours. Raw data was downloaded and converted into fastq file format using Guppy_basecaller. Barcodes were sorted by de-multiplex using Guppy_barcoder and reads were filtered by quality (Filtlong) and length (Cutadapt). Vsearch identified chimeras which were then removed. Classification of bacteria taxa was identified using EMU NCBI Reference Database. Bacterial taxa were removed by EMU Error Correction based on alignment and abundance profiles. Bacterial taxa with < 1 per 10,000 reads were removed.

Statistical Analysis

The Tukey HSD ("honestly significant difference") was used for analyzing plant biomass by cover crop and soil treatment. Plant biomass statistical analysis, using fresh biomass for cover crops and dry biomass for peaches, TukeyHSD() from the multcompView package in RStudio was used. For regressions analyzing soil nutrients from the end of the peach experiment, both peach dry biomass and fresh peach biomass was used. The Lagrange Multiplier test was used for the regressions fit using the R function lm with broom and tidy-verse packages in RStudio.

Research results and discussion:

Effect of Soil Disruption on Cover Crop Growth

All cover crops grown in disrupted soils had a higher biomass (Fig. 1 and 2). Corn grown in disrupted soils had the highest biomass out of all treatments. Due to different life strategies, the differences between cover crops were not intended to be compared. However, the differences in biomass between disrupted and not disrupted treatments are worth highlighting. Biomass of corn and tomato were significantly different between their respective soil treatments. Alfalfa and fescue, which can be considered more traditional cover crops, did not have significantly different biomass with their respective soil treatment. Results demonstrate that soil sterilization significantly increased flowering (alfalfa p 0.0401, tomato p < 0.0001), height (corn p < 0.0001, tomato p < 0.0001), and biomass (alfalfa p = 0.0415; corn p < 0.0001, fescue p = 0.0019, and tomato p < 0.0001). All metrics within this study indicate that soil disruption improved plant health. 

Figure 1. Cover crop fresh biomass by soil Treatment: The mean of all the different cover crops was compiled to visualize how effective soil disruption was to increase cover crop biomass. Cover crops grown in disrupted soils developed significant higher biomass than cover crops grown in un-disrupted (un-treated) soil. 

Figure 2. Cover crop above fresh biomass. When separated by both soil and crop treatment, the positive effect that soil disruption had on cover crop biomass was observed in every crop. Within disrupted soils, it was found that corn had the highest and significantly different biomass. In terms of significance, only corn and tomato were found to be different by soil treatment. The differences between alfalfa and fescue were not found to be significant by soil treatment.

 Effect of Soil Disruption and Cover Crop Reincorporation on Peach Growth

Peach saplings in soils that had not been previously disturbed via steam autoclave had the highest dry biomass for all cover crop treatments. Both fresh and dry peach biomass were recorded. Dry biomass removes the constantly fluctuating water concentrations within plant tissues and is used for data visualization since it is a more reliable measure. Peach saplings in untreated soil which previously had alfalfa had the highest biomass. Although not significantly different than other cover crops grown in untreated soils, peach saplings grown in untreated soils with alfalfa previously had a significantly higher biomass than all peaches cultivated in disrupted soils. Within disrupted soil treatments, peaches grown in alfalfa had the highest biomass and was significantly higher than peach trees in soils which previously had corn and fescue. To consider other metrics, Supp. Fig.  1 visualizes the separation between above and below ground peach biomass. Replant disease is known to reduce below ground biomass specifically. In undisrupted soil treatments, where microorganismal populations which contribute to replant disease were not disrupted via steam autoclave, peach biomass was significantly higher than disrupted soil treatments. Relatively, disrupted soil treatments did not show reduced plant biomass, a symptom of replant disease, during the cover crop trials. However, reduced peach biomass was shown to be stronger in initially disrupted soils during the peach trials. Other metrics recorded were diameter and height. After 12 weeks, trees grown in non-autoclaved soils were significantly larger (height p = 0.0055, diameter p < 0.0001). In all, peach trees grown in soils which had not been disrupted via steam autoclave had the highest biomass, with no readily apparent trend in above and below ground biomass.

Figure 3. Peach dry biomass by soil treatment. The mean of peach sapling dry total biomass was significantly higher in soil that had never been disrupted via steam autoclave. Peaches grown in disrupted soils developed less biomass than peaches grown in un-disrupted soil. 

Figure 4. Total dry peach biomass. A trend that biomass was higher for peach trees grown in soil which had not been disrupted via steam autoclave was observed for every cover crop treatment. All cover crop non-disrupted treatments showed a significant increase in biomass between soil treatment pairs. Alfalfa, in untreated soils, performed relatively the best, but was not significantly different than any cover crop treatment. No cover crop controls which later had peaches growing showed no significant difference in biomass.

Supplementary Figure 1. Dry root and shoot peach biomass. Peach dry biomass was higher in soil treatments which had not been disrupted via steam autoclave (Figures 3 and 4). After cover crop biomass was reincorporated into the soil, peach trees were grown in the same 1-gallon pot. Soil was not disrupted (via autoclaved) again in between growing the cover crops and the peaches. The top 3 cm of soil for all pots were disturbed mechanically, since during the reincorporation of cover crop residues crops were buried beneath the soil. After two weeks, the soil was again mechanically disturbed, at a depth of up to 15 cm in the center of the pot to accommodate the peach sapling roots with minimal damage.

Supplementary Table 1. Peach height was significantly higher for peaches grown non-disrupted soils with a cover crop of alfalfa as compared to all treatments.

Supplementary Table 2. Peach height was significantly higher for peaches grown non-disrupted soils with a cover crop of alfalfa as compared to all treatments.

Figure 5. Prunus spp. rootstock above and bellow ground fresh biomass by soil treatment. The mean of all the different rootstocks was compiled to visualize how effective soil disruption was to increase rootstock biomass. Rootstocks grown in disrupted (sterile) soils developed slight higher biomass than rootstocks grown in un-disrupted (non-sterile) soil. The only rootstock that developed significantly higher biomass as a result of the soil disruption was the RD susceptible 'Lovell'.

 

Research conclusions:

Replant disease (RD) is characterized by reduced crop productivity resulting from repeated plantings of genetically related crops. This globally relevant disease is thought to be primarily caused by soil borne pathogenic microorganisms with specialized antagonistic traits towards the specific crop.  We hypothesize that using cover crops or different rootstock genotypes grown in disrupted soils could be employed to beneficially alter the microbiome of RD soils for peach orchards. Steam autoclaving was used to disrupt the soils to amplify the microbiome interactions in the soil. Four different crops (corn, tomato, fescue, and alfalfa) were grown in disrupted and non-disrupted RD soil from Grand Junction, CO under greenhouse conditions. We show that soil disruption significantly increased biomass of all crops (alfalfa p= 0.0415; corn p < .0001, fescue p= 0.0019, and tomato p < .0001). Cover crops were reincorporated into the soil and subsequently RD susceptible 'Lovell' peach saplings were planted. After 12 weeks, trees in non-disrupted soils were significantly larger (height p= 0.0055, diameter p < .0001). Crop type alone had no significant impact on tree size, however when considering soil sterilization, alfalfa in non-sterilized soil resulted in increased tree height, and total leaves. These preliminary results suggest that alfalfa could alleviate peach trees in RD soil and is currently established in the experimental orchards for field evaluations. For the rootstock genotype experiment, the growth of 7 Prunus spp. rootstocks of variable vigor ('Hansen 536', 'Trio-2507', 'Trio-2207', 'Krymsk86', 'MP-29', 'RootPac20', and 'Controller6') were compared to RD susceptible 'Lovell' trees in disrupted and non-disrupted RD soil. Peach trees in disrupted soils grew larger (height p = 0.0001, diameter p = 0.0022). Controller6, Krymsk86, MP-29, Trio-2507, 'Trio-2207', Hansen 536 and RootPac20 may be RD resistant by showing above and below biomass growth compared to RD susceptible 'Lovell' but no significant differences between soil treatment. Combining RD resistance performance and vigor classification 'Krymsk86',  'RootPac20' and 'Trio-2207' were selected for field evaluations. Future studies will reveal if a shift of the microbiome can be correlated with peach health, to develop a cropping technique that can be applied to other tree fruit systems with RD.

Participation Summary
3 Farmers participating in research

Education

Educational approach:

Educational tools and research findings are disseminated locally, regionally, nationally, and globally. Results are presented at conferences, such as those held by the WCHS and IFTA etc. to reach the grower community and national and international conferences. Scientific peer reviewed articles have been published to disseminate results to the scientific community. Seasonal workshops, field days, webinars and tours are held at CSU’s WCRC-OM to provide updates to the grower community. Finally, to quantify and maximize producer adoption two surveys at the start and the termination of the project will be performed as well as follow-up communication and feedback with researchers, agriculture professionals and extension personnel. Educational approach includes, factsheets, and website updates with information on the effect of cover crops and tolerant rootstocks to manage RD will be developed and disseminated to stakeholders. 

Educational & Outreach Activities

15 Consultations
1 Curricula, factsheets or educational tools
3 Journal articles
2 On-farm demonstrations
2 Tours
6 Webinars / talks / presentations
3 Workshop field days

Participation Summary:

150 Farmers
15 Ag professionals participated
Education/outreach description:

Journal articles

Paper on the impact replant and alkaline soil tolerant rootstocks. Black BL, Minas IS, Reighard GL, Beddes T, 2021. Alkaline soil tolerance of rootstocks included in the NC-140 ‘Redhaven’ peach trial. Journal of the American Pomological Society, 75, 9-16.

Paper on the impact of training system and rootstock genotype and vigor on peach fruit productivity was published in September 2021. Anthony BM, Minas IS, 2021. Optimizing Peach Tree Canopy Architecture for Efficient Light Use, Increased Productivity and Improved Fruit Quality. Agronomy 11 (10), 1961.

Paper on the impact of semi-dwarf and replant tolerant rootstocks on peach production and quality was presented in the ISHS XII Orchard Systems Symposium and submitted for publication in July 2021. Minas, I.S., Reighard, G.L., Brent Black, B., Cline, J.A., Chavez, D.J., Coneva, E., Lang, G., Parker, M., Robinson, T., Schupp, J., Francescato, P., Jaume Lordan, J., Tom Beckman, T., Shane, W., Sterle, D., Pieper, J., Cathy Bakker, C., Clark, B., Ouellette, D., Swain, A., Winzeler, H.E. 2021. Establishment performance of the 2017 NC-140 semi-dwarf peach rootstock trial across 10 sites in North America. Acta Horticulturae accepted.

Extension Fact Sheets

Extension Fact Sheet on Peach Rootstocks submitted to CSU Extension in September 2021 and is currently under review from external reviewers. Minas IS, Anthony BM, Pieper J. Suitable peach rootstocks for western Colorado growing conditions. CSU Extension under review.

Talks at grower meetings

Minas IS, Orchard & Environmental Factors Affecting Peach Productivity & Harvest Quality, Great Lakes EXPO, Grand Rapids, MI, December 2021.

Minas IS, Orchard & Environmental Factors Affecting Peach Productivity & Harvest Quality, Western Colorado Horticultural Society Annual Meeting, Grand Junction, CO, January 2022.

Minas IS, 2017 NC-140 Semi-Dwarf Peach Rootstock Trial, International Fruit Tree Association Annual Meeting, Hersey, PA, February 2022.

Talks at scientific meetings

Minas IS, Reighard GL, Black B, Cline JA, Chavez DJ, Coneva E, Lang G, Parker M, Robinson T, Schupp J, Francescato P, Lordan J, Beckman T, Shane W, Sterle D, Pieper J, Bakker C, Clark B, Ouellette D, Swain A, Winzeler HE. Establishment performance of the 2017 NC-140 semi-dwarf peach rootstock trial across 10 sites in North America. Oral Presentation at ISHS XII International Symposium on Integrating Canopy, Rootstock & Environmental Physiology in Orchard Systems, Wenatchee, WA, July 2021.

Newberger D, Vivanco J, Minas IS. Using soil disruption followed by cover crops and rootstocks to alleviate peach replant disease. Oral Presentation at ISHS X International Peach Symposium, Naousa, Greece, May 2022.

Webinars

Webinar on CSU Pomology Research Program at Western Colorado Research Center at Orchard Mesa (WCRC-OM) updates in February 2021 under the frame of Western Colorado Horticultural Society (WCHS) with 65 attendees.

Workshops

Workshop and field demonstration to educate growers and disseminate research findings on Principles of Fruit Production for Beginners Growers was offered at Western Colorado Research Center at Orchard Mesa (WCRC-OM) in January 17, 2022 under the frame of Western Colorado Horticultural Society (WCHS) with 40 attendees.

Field Demonstrations

Field demonstrations of Rootstocks, Pruning and Training Systems in Peach was offered at Western Colorado Research Center at Orchard Mesa (WCRC-OM) in February 21, 2022 with 45 attendees.

Field days

Upcoming: Annual CSU Pomology Field Day to cover peach rootstocks, training systems, cover crops and replant disease management in May 9th, 2022

Learning Outcomes

85 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Key areas taught:
  • soil health
  • orchard replant disease
  • cover crops
  • beneficial microbes
  • rootstocks

Project Outcomes

5 Farmers changed or adopted a practice
50 Farmers intend/plan to change their practice(s)
5 New working collaborations
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.