Management of soilborne diseases in small farms with eco-friendly treatment options

Management of soilborne diseases in small farms with eco-friendly treatment options

Summary

Two on-farm trials were conducted with heirloom tomato ‘Mortgage lifter’ at the WVU Organic Farm and Pierson Farm to investigate the efficacy of bio-fumigants, biological antagonists, and resistant rootstock in managing soil-borne tomato wilt diseases. Six different treatments were: 1) “Caliente” mustard cover crop incorporated in the soil; 2) Mustard meal (bio-fumigant); 3) Serenade soil (Bacillus subtilis strain QST 713); 4) Prestop (Gliocladium catenulatum); 5) Grafted tomatoes (Mortgage Lifter scion on resistant rootstock “Maxifort”) and 6) Non-treated control. Mustard cover crop was seeded in the randomly allocated plots in four replicates followed by tissue maceration and incorporation in the spring of 2015. Plants were grown in biological control agents (BCA) treated growing mix and regular mix to represents treatments mentioned above. Products for intended BCAs were also applied in the planting holes in the field at the time of planting. Thirty five days after planting in contaminated soil, grafted tomato plants showed significantly higher plant vigor compared with non-treated check. All treatments had significantly lower symptomatic leaves than that of non-treated check at 35 days after planting. Cumulative harvests for six weeks showed that yield from all treatments except mustard cover crop were significantly (P<0.001) higher compared with non-treated check. Grafted plants produced 20 lb tomatoes/plant compared with only 11 lbs by non-treated check. Results suggest that organically acceptable methods can provide significant yield advantage to heirloom tomatoes in soilborne pathogen infested soil. Field days were organized to demonstrate the results to growers who attended. Additional dissemination of results took place through NEIPM webinar and WVU extension service annual meeting presentation.

Objectives/Performance Targets

1. Identify wilt causing organisms up to race/pathovar level to better understand population structure in WV that should help matching resistant variety;
2. Assess the efficacy of soil treatment with bio-fumigants and biological antagonists in mitigating soilborne disease severity;
3. Assess the usefulness of grafted tomato in managing wilt disease;
4. Measure yield advantage due to treatment of soil with potential bio-fumigant and biological antagonists;
5. Disseminate the technology to organic growers and small farmers through individual communication, grower meetings and conferences, annual field day events, newsletters and cooperative county extension programming.

Accomplishments/Milestones

• April 28, 2015: Caliente Mustard was seeded in appropriate treatment plots
• May 12, 2015: 220 ‘Mortgage Lifter’ seeds were planted in 288 plug trays as well as 40 ‘Maxifort’ rootstock seeds, 140 of the ‘Mortgage Lifter’ seeds were left untreated, 40 were planted in organic media treated with Serenade, and 40 were planted in the same media treated with Prestop
• June 8, 2015: Plastic grafting chamber with a humidifier was set up to graft the plants for treatment 5, humid chamber was tested and 20 ‘Mortgage lifter’ scions were grafted onto the 20 best rootstock plants.
• June 16, 2015: Mustard meal and Caliente mustard plants were incorporated into the soil.
• June 17, 2015: Prepared inoculum from Verticillium that was isolated in the WVU Plant Diagnostic lab, sprayed Verticillium inoculum @ 2.49 x 10^5 cfu/ml over the area of all the plots followed by laying plastic mulch.
• July 2, 2015: Made plastic mulch beds and planted tomatoes, were supported with strings and stakes
• August 13-14, 2015: Organic farm and Pierson farm field day.
• September 2-October 15, 2015: Harvested tomatoes, cumulative yield data obtained, analyzed and presented at NIIPM webinar, submitted a PDMR reports for publication.
• October 16-December 16, 2015: Collection of isolates from diseased samples, molecular analysis.
• February 27, 2016: Results will be presented at WVU small farm conference.

Impacts and Contributions/Outcomes

• Grafting of ‘Mortgage Lifter ‘on resistant root stocks was 100% successful. Cooperating growers and field day attendees were very interested in grafting their own plants especially heirloom type tomatoes.
• Due to short frost free growing season, spring seeding of mustard seed cover crop may not be feasible. Achieving the optimum growth stage followed by incorporation in the soil compromises the planting date. We need to explore the option of fall seeding and incorporation before frost kill of mustard plants and determine the efficacy of such treatments. However, our data showing mustard meal can provide similar or slightly better disease suppression. We also need to conduct multi-year and multi-location trial to assess the reproducibility of data although in this year’s trials all treatments showed significantly lower disease compared to non-treated control.
• Cumulative harvests for six weeks showed that yield from all treatments except mustard cover crop were significantly (P<0.001) higher compared with non-treated check. Grafted plants produced 20 lb tomatoes/plant compared with only 11 lbs by non-treated check.
• We could or hoping to reach out to many small growers in our state to show the results and anticipate many of them will adopt the new technology for managing soilborne diseases.

Collaborators: