Biofumigants for Sustainable Soil-borne Disease Management in Nursery Production

Final report for OS18-112

Project Type: On-Farm Research
Funds awarded in 2018: $15,000.00
Projected End Date: 03/14/2020
Grant Recipient: Tennessee State University
Region: Southern
State: Tennessee
Principal Investigator:
Dr. Fulya Baysal-Gurel
Tennessee State University
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Project Information

Abstract:

Biofumigation in combination with solarization can provide a more successful and sustainable solution for improving soil quality and enhancing natural soil-borne disease control in field grown production systems of woody ornamentals, specifically at the propagation stage. Despite the advantages of these sustainable techniques, grower adoption of these types of management strategies are low due to concerns about efficacy, economic cost, and compatibility with their production practices. These issues need to be resolved through on-farm research and demonstrated under commercial production conditions to make biofumigation in combination with solarization part of an accepted, sustainable field-grown nursery production system for growers in the South.

Based on the results of a previous SSARE-funded grant (GS16-155), cover crops like white mustard, purple top forage turnips, astro arugula, mighty mustard, dwarf essex rape, amara mustard and oriental mustard may have potential for use in biofumigation against soil-borne pathogens of woody ornamental plants. Work is needed to examine these cover crops in a field production environment that offers potential fungicide-like properties while still providing benefits such as increased soil fertility.

Project Objectives:

Our objectives are:

  • Assess environmentally friendly biofumigants in combination with solarization for soil-borne diseases and improved plant growth;
  • Examine economic benefits and obstacles of using biofumigants in combination with solarization;
  • Engage in outreach and technology transfer with field nursery growers.

Cooperators

Click linked name(s) to expand
  • Terri Simmons (Researcher)

Research

Materials and methods:

Experimental design and data collection.

TSUNRC 2018 and 2019 field trials with Phytophthora nicotianae inoculation. Field experiment was conducted at experimental field plot at the TSUNRC, McMinnville, TN in 2018 and 2019. Ground beds were artificially inoculated with Phytophthora nicotianae based on established protocol (Benson and Tjosvold, 2008 and Liyanapathiranage, 2017). Infested/non-biofumigated non-covered, non-infested/non-biofumigated non-covered plots were used as controls. Treatments were white mustard, purple top forage turnips, astro arugula, mighty mustard, dwarf essex rape, amara mustard, oriental mustard, biofumigant DOMINUS (allylisothiocyanate) (at 170 and 340 lb/A), mustard meal and only solarization. Biofumigant cover crops were seeded into 8.0 x 2.5 m beds with a seed rate provided by manufacturer. Plots were in a completely randomized design with four replications per treatment. Flowering biofumigant plants were dug from randomly chosen 0.25 m2 areas in each plot to determine plant biomass volumes. Flowering biofumigants were chopped and incorporated 15-cm deep into the soil. After incorporation, plots were covered with polyethylene film for 30 days. Biofumigant DOMINUS (at 170 and 340 lb/A) will be applied in dedicated plots same day, and those plots will be covered with polyethylene film for 30 days as well. Before and after application of treatments, population density of the pathogen(s) was determined using selective media. The soil samples were collected using a generic soil probe and processed using established protocol. Temperature and soil moisture in the plots were monitored using WatchDog. After the 30-day period, boxwood plants provided by a commercial nursery were transplanted into the experimental plots infested with Phytophthora (5 plants per treatment). Assay was run for 3 months. Disease occurrence, incidence, phytotoxicity and defoliation were evaluated throughout the trial. At the end of the three months, root systems were assessed for disease severity using a scale of 0-100% roots affected, and subsamples were plated on PARPH-V8 medium to determine the percent recovery of Phytophthora. Phytophthora infection was determined by plating ten randomly selected root samples (~1 cm long) from the root tips of each plant (ten replications per treatment) on PARPH-V8 medium (Ferguson and Jeffers 1999).  The presence or absence of Phytophthora growth surrounding each root sample was recorded after 1 week. For PARPH-V8 selective medium, 0.50 g CaCO3(98% Acros Organics, Geel, Belgium) was added to 50 ml V8 juice (Campbell, Camden, NJ) and centrifuged for 10 min at 7,000 rpm.  The buffered and clarified V8 juice was added to 450 ml deionized water, along with 7.5 g agar (Sigma-Aldrich, St. Louis, MO) and autoclaved for 15 min.  Afterwards, 500 µL of the fungicide and antibiotics [pentachloronitrobenzene (PCNB) (99% (GC) Sigma-Aldrich, St. Louis, MO) (0.63 g/50 ml ethanol), ampicillin (Sigma-Aldrich, St. Louis, MO) (1.25 g/50 ml ethanol), rifampicin (Sigma-Aldrich, St. Louis, MO) (0.05 g/50 ml ethanol), pimaricin (2.5%) (MP Biomedicals, Santa Ana, CA), and hymexazol (Sigma-Aldrich, St. Louis, MO) (250 mg/50 ml sterilized water)] were added to the medium (Jeffers and Martin 1986; Ferguson and Jeffers 1999). Plant height and width were recorded at the beginning and at the end of the trial to determine the height and width increases. Total fresh weight and root weight also recorded at the end of the trial.

On-farm trial with natural pathogen pressure. This experiment was conducted in the field plots with the history of Phtophthora root rot issue at a commercial nursery in Winchester, TN. The field was fertilized with nitrogen, phosphorus and potassium based on University of Tennessee soil test recommendations. Treatments were mighty mustard ‘Pacific Gold’, Yellow mustard ‘White Gold’, Brown mustard ‘Kodiak’ and only solarization (Table 1). Non-biofumigated, non-covered plots were used as control. Plots were in a completely randomized design with three replications per treatment. Biofumigant cover crops were planted with a seed rate provided by manufacturer in April 3, 2019. Flowering biofumigants were rototilled 6 in. deep into the soil in May 26, 2019. After incorporation, plots were covered with polyethylene film for 30 days. Those plots and solarization-only plots were covered with polyethylene film for 30 days as well and removed in June 27, 2019. Soil temperature in the plots was monitored using WatchDog. After the 30-day period, the polyethylene film was removed and uniform boxwood cuttings (B. sempervirens ‘Green Velvet’) were planted into the plots, with 20 plants per plot. Plant growth data (fresh weight and root weight) were recorded on 10 randomly selected rooted boxwood cuttings/per replication and roots were assessed for Phytophthora root rot disease severity using a scale of 0-100% roots affected at the end of experiment.

Statistical analyses. Statistical analyses were performed in SAS statistical software. Analyses of variance was conducted on the data estimates of disease severity and measures of plant health using mixed model. Means comparison was performed using Fisher's LSD test.

Research results and discussion:

TSUNRC 2018 trial with Phytophthora nicotianae inoculation: Average soil temperature of solarized beds was 91.58°F between August 8 and September 7, 2018; average soil temperature of cover crops incorporated solarized beds was 97.5°F; average soil temperature of control non-treated, non-solarized beds was 78.6°F (data not shown). All treatments except both rates of Dominus and turnip ‘Purple top forage’ significantly reduced Phytophthora root and crown rot disease severity compared to the inoculated, non-biofumigated, non-solarized control (Table 1). Mustard green ‘Amara’ incorporation with solarization significantly increased the total fresh weight compared to other treatments and controls. There was no significant difference between treatments considering the root weight. Phytotoxicity were not observed in any of the boxwood plants.

Table 1. Efficacy of biofumigants with solarization in suppression of Phytophthora root rot in field grown boxwood, 2018 Trial.

Treatment

Seed rate or application rate

Phytophthora root rot severity

(%)*

Total fresh weight        (oz)

Root weight        (oz)

Inoculated control

N/A

60.5 a**

0.5 b

0.3 a

Non- inoculated control

N/A

0.0 e

0.7 b

0.4 a

Arugula ‘Astro’

30-50 seeds/ft2

44.3 cd

0.6 b

0.3 a

Brown mustard ‘Kodiak’

15 seeds/ft2

41.8 d

0.6 b

0.4 a

Mighty mustard ‘Pacific Gold’

15-20 lb/A

37.3 d

0.9 b

0.3 a

Mustard green ‘Amara’

15 seeds/ft2

44.3 cd

1.8 a

0.3 a

Rape ‘Dwarf essex’

5-10 lb/A

46.8 bcd

0.6 b

0.3 a

Turnip ‘Purple Top Forage’

5-8 lb/A

53.0 abc

0.6 b

0.3 a

Yellow mustard ‘White Gold’

15-20 lb/A

39.3 d

0.7 b

0.4 a

Dominus

170 lb/A

56.8 ab

0.6 b

0.4 a

Dominus

340 lb/A

54.3 abc

0.6 b

0.3 a

Mustard meal

968 lb/A

49.3 bcd

0.7 b

0.4 a

Solarization

N/A

46.8 bcd

0.6 b

0.3 a

P-value

 

<0.0001

<0.0001

<0.0001

*Disease severity based on percentage of roots affected.

**Values are the means of 20 plants; treatment followed by the same letter within a column are not significantly different at P ≤ 0.05.

 

TSUNRC 2019 trial with Phytophthora nicotianae inoculation: Average soil temperature of solarized beds was 91.8°F between June 17 and July 18, 2019; average soil temperature of cover crops incorporated solarized beds was 98.6°F; average soil temperature of control non-treated, non-solarized beds was 83.8°F (data not shown). All treatments except both rates of Dominus significantly reduced Phytophthora root rot disease severity compared to the inoculated, non-biofumigated, non-solarized control (Table 2). ‘Amara’ mustard, brown mustard 'Kodiak' and solarization alone resulted lower Phytophthora root rot severity compared to the inoculated, non-biofumigated, non-solarized control, were no different than the non-inoculated, non-biofumigated, non-solarized control. Boxwood plants grown in Arugula ‘Astro’ plots had a higher increase in height compared to the inoculated, non-biofumigated, non-solarized control and high rate of Dominus. Average width increase, total plant weight and total root weight were not significantly different among treatments. Phytotoxicity was not observed in any of the boxwood plants.

 

Table 2. Efficacy of biofumigants with solarization in suppression of Phytophthora root rot in field grown boxwood, 2019 Trial.

Treatments

Seed rate or application rate

Height increase

(cm)

Width increase

(cm)

Total weight

(g)

Root weight

(g)

Phytophthora Root Rot Severity (%)

Inoculated control

N/A

1.2 b

2.1 a

16.7 a

10.5 a

62.0 a

Non- inoculated control

N/A

1.9 ab

2.5 a

19.0 a

11.7 a

15.0 g

Arugula ‘Astro’

30-50 seeds/ft2

2.3 a

3.6 a

21.3 a

13.9 a

35.2 cde

Brown mustard ‘Kodiak’

15 seeds/ft2

1.7 ab

2.7 a

16.3 a

10.0 a

28.0 d-g

Mighty mustard ‘Pacific Gold’

15-20 lb/A

1.9 ab

2.4 a

17.0 a

10.7 a

31.7 c-f

Mustard green ‘Amara’

15 seeds/ft2

1.3 ab

2.3 a

21.2 a

13.7 a

24.7 efg

Rape ‘Dwarf essex’

5-10 lb/A

2.1 ab

2.1 a

17.6 a

11.1 a

39.2 cd

Turnip ‘Purple Top Forage’

5-8 lb/A

1.8 ab

2.2 a

16.9 a

11.2 a

41.2 cd

Yellow mustard ‘White Gold’

15-20 lb/A

1.9 ab

2.1 a

18.2 a

11.2 a

44.0 bc

Dominus 

170 lb/A

1.5 ab

2.9 a

14.9 a

9.6 a

56.5 ab

Dominus 

340 lb/A

1.1 b

3.2 a

16.0 a

10.1 a

60.7 a

Mustard meal

968 lb/A

1.5 ab

2.2 a

16.3 a

10.1 a

35.7 cde

Solarization

N/A

1.3 ab

1.9 a

16.1 a

10.4 a

20.9 fg

 

 

<0.01

<0.052

<0.058

<0.047

<0.0001

*Disease severity based on percentage of roots affected.

**Values are the means of 20 plants; treatment followed by the same letter within a column are not significantly different at P ≤ 0.05.

 

On-farm trial with natural pathogen pressure: Average soil temperature of solarized beds was 88.2°F between May 26 and June 27, 2019; average soil temperature of cover crops incorporated solarized beds was 92.4°F; average soil temperature of control non-treated, non-solarized beds was 85.7°F (data not shown). In a trial without the artificial inoculation of pathogen, disease severity was low to moderate. All treatments significantly reduced Phytophthora root rot severity compared to the non-biofumigated, non-covered control with the exception of yellow mustard ‘White Gold’ (Table 3). Plant height increase was not significantly different among treatments. Total weight, root weight and plant width increase were greater in boxwood plants treated with yellow mustard ‘White Gold’ compared to the other treatments.

 

Table 3. Efficacy of biofumigants with solarization in suppression of Phytophthora root rot in field grown boxwood, On-farm Trial.

Treatment

Seed rate

Height increase

(cm)

Width increase

(cm)

Total weight

(g)

Root weight

(g)

Phytophthora root rot severity (%)

Control

N/A

1.52 a

4.32 b

3.2 b

0.74 b

27.5 a

Mighty mustard ‘Pacific Gold’

15-20 lb/A

1.50 a

4.75 ab

3.1 b

0.90 b

18.0 b

Yellow mustard ‘White Gold’

15-20 lb/A

1.65 a

5.35 a

4.1 a

1.42 a

20.3 ab

Brown mustard ‘Kodiak’

15 seeds/ft2

1.42 a

4.57 ab

3.4 ab

0.90 b

18.8 b

Solarization

N/A

1.82 a

4.58 ab

3.2 b

0.76 b

17.7 b

 

 

0.5693

<0.013

<0.002

<0.0001

<0.002

*Disease severity based on percentage of roots affected.

**Values are the means of 30 plants; treatment followed by the same letter within a column are not significantly different at P ≤ 0.05.

 

Boxwood growers can use information from this study and can be benefited by using biofumigant crops with solarization to manage Phytophthora root rot in their field production.

Participation Summary
1 Farmer participating in research

Educational & Outreach Activities

15 Consultations
2 Curricula, factsheets or educational tools
6 Journal articles
2 On-farm demonstrations
2 Published press articles, newsletters
2 Tours
8 Webinars / talks / presentations
5 Workshop field days
1 Other educational activities: Seminar at University of Georgia Department of Plant pathology and Workshop at Georgia Winter Green Advanced Pest & Disease Workshop, Duluth, GA
01/24/2019

Participation Summary:

200 Farmers
150 Ag professionals participated
Education/outreach description:

Two review papers and four research articles were published in peer- reviewed scientific journals (Agriculture, Canadian Journal of Plant Pathology, SNA Research Conference Proceeding, Plants, Archives of Phytopathology and Plant Protection and Plant Health Progress). The progress regarding this work was presented to stakeholders, extension agents and other researchers through field and demonstration days in 2018 and 2019 at the TSUNRC, nursery association meetings (Middle Tennessee Nursery Association and Southern Nursery Association, Georgia Winter Green), seminar at University of Georgia and presented at scientific conferences (2019 American Phytopathological Society annual meeting, Cleveland, OH; 97th Southern division APS meeting. Feb 9-12, 2020. Charleston, SC; 129th Tennessee Academy of Science meeting at Columbia State Community College, Columbia, TN. November 22, 2019  ). The graduate student has been working on this project received awards with her presentations at the meetings (97th Southern division APS meeting. Feb 9-12, 2020. Charleston, SC.-First place- Southern division APS meeting poster competition and she received also traveled award; 129th Tennessee Academy of Science meeting at Columbia State Community College, Columbia, TN. November 22, 2019-Second Place- Poster presentation). The PI organized 3 days Boxwood Diseases & Pests workshop in Clarksville, Lebanon and Nashville, TN between November 13-15, 2019 presenting the results related with this project. The PI also published extension articles for Tennessee Greentimes and Chase digest.

 

PEER REVIEWED JOURNAL ARTICLES

Panth, M., Hassler, S., and Baysal-Gurel, F. 2020. Methods for management of soilborne diseases in crop production. Agriculture 10(1), 16; https://doi.org/10.3390/agriculture10010016

Neupane, S., Simmons, T., and Baysal-Gurel, F. 2020. Management of Phytophthora root and crown rot using biofumigation on field grown boxwood. SNA Research Conference Vol; 64 2020. Pathology and Nematology Section (S. Neupane received the SNA Student Travel Grant).

Baysal-Gurel, F., Liyanapathiranage, P., Addesso, K. 2019. Effect of Brassica crop-based biofumigation on soilborne disease suppression in woody ornamentals. The Canadian Journal of Plant Pathology. DOI: 10.1080/07060661.2019.1625444.

Baysal-Gurel, F., Kabir, N., Liyanapathiranage, P. 2019. Effect of Organic Inputs and Solarization for the Suppression of Rhizoctonia solani in Woody Ornamental Plant Production. Plants 20198(5), 138; https://doi.org/10.3390/plants8050138.

Baysal-Gurel, F., Liyanapathiranage, P. 2019. Pathogenicity of Rhizoctonia solani and Phytophthora nicotianae to Brassicaceae cover crops. Archives of Phytopathology and Plant Protection. Page:1-15. DOI: 10.1080/03235408.2019.1617499.

Baysal-Gurel, F., Liyanapathiranage, P., Mullican, J. 2018. Biofumigation: opportunities and challenges for control of soilborne diseases in nursery production. Plant Health Progress. 19:332-337. https://doi.org/10.1094/PHP-08-18-0049-RV P. 332-337

 

EXTENSION PUBLICATIONS

Baysal-Gurel, F. 2020. Phytophthora root and crown rot of boxwood. Tennessee Greentimes. Volume 21/No. 1 Spring 2020.

Baysal-Gurel, F. 2019. Control of Phytophthora on boxwood. Chase Digest August 2019 Issue Volume 7(8).

Learning Outcomes

12 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Key changes:
  • Improve the productivity and sustainability of intensive field grown nursery production bu adopting biofumigant usage

  • Usage of biofumigant cover crops for soil borne disease management

Project Outcomes

12 Farmers changed or adopted a practice
2 Grants received that built upon this project
3 New working collaborations
Project outcomes:

As a researcher-nursery grower team, we propose to promote the adoption of biofumigants by documenting their effects and returns in multiple nursery systems. We emphasize that the development of a multiple systems approach to improve soil-borne disease management, soil quality and fertility using biofumigants will help improve the productivity and sustainability of intensive field grown nursery production.

Information Products

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.