Optimizing anaerobic soil

disinfestation for Tennessee

D.M. Butler*, S.E. Eichler Inwood, D.G. McCarty, C.E. Sams and A.L.

Wszelaki, Dept. of Plant Sciences, Univ. of Tennessee, Knoxville, TN

B.H. Ownley and M.E. Dee, Dept. of Entomology and Plant

Pathology, Univ. of Tennessee, Knoxville, TN

N. Kokalis-Burelle and E.N. Rosskopf, USDA-ARS, Fort Pierce, FL

Background

• Developed as an alternative to soil

fumigation in the Netherlands and Japan

• Demonstrated control in diverse locations

for a range of soilborne plant pathogens

and plant-parasitic nematodes

(photos: J. Muramoto, D.M. Butler, S.E. Eichler Inwood)

ASD treatment steps

1. Incorporate easily-decomposable organic material

– Provides carbon source for soil microbes

2. Tarping with polyethylene mulch

– Prevents resupply of oxygen

– Allows volatile compounds to accumulate

– Can increase soil temperature

3. Irrigate to saturation of topsoil

– “Flush” air-filled pore space

– Provide adequate moisture for microbial growth

ASD treatment

• Rapid growth of soil microbes depletes

soil oxygen

• Resupply of oxygen limited by high soil

moisture content and tarp

• Soil microbial community shifts towards

anaerobic microorganisms

• Anaerobic condition persists until C

source utilized and/or soil moisture

content drops (typically 1 to 2 weeks)

ASD mechanisms of control

• Toxic by-products of anaerobic

decomposition

– Organic acids (e.g. acetic, n-butyric)

– Volatile compounds

• Reduced metal ions (e.g. Fe2+)

• Biocontrol by soil microorganisms

• Heating by solarization (if applicable)

• Additive or interactive effects of the above

ASD for Tennessee

• Considerable progress adapting technology

to FL vegetable (e.g., Butler et al., 2012a;

Rosskopf et al., 2012) & CA strawberry

production (e.g., Shennan et al., 2011; 2012)

• Need to evaluate and optimize for other

production regions in the country

– C amendments

– Environmental conditions

– Soil types

– Cropping systems/seasonality

Tennessee production systems

• Recent CUEs: tomato, pepper,

cucurbits, strawberry

• In contrast to FL vegetable production

systems:

– Winter fallow

– Fumigation primarily occurs in mid-spring

– Soil temperatures range from 15 to 25 C at

a 10 to 15-cm soil depth under black PE

mulch

C source amendments and rates • California

– Rice bran (4.5 to 9 t/acre; ~5.5 to 11 mg C g-1 soil)

– Mustard cake, mustard seed meal, ethanol

• Florida – Liquid molasses (3.5 t dry matter/acre,

~4.5 mg C g-1 soil in raised bed)

– Cover crop residue (variable)

• Tennessee – Dry molasses (~1.3 to 2.5 t/acre, 1 to

2 mg C g-1 soil)

– Cover crop residue (variable, 1 to 4.2 mg C g-1 soil)

– Future work: wheat bran

(photos: J. Muramoto, E.N. Rosskopf, D.M. Butler)

Objectives

1. Evaluate soil temperature and C

impacts on pathogen and weed control

during ASD (controlled environment)

2. Evaluate C source impacts on

pathogens, weeds, crop performance,

and soil properties in a field experiment

3. Demonstrate ASD methods versus

grower standard chemical controls

Controlled environment studies

• Pathogens

– Rhizoctonia solani

– Sclerotinia

sclerotiorum

• Soil temperatures

– 15 C to 24 C

• C-source treatments

– Crimson clover

– Hairy vetch

– Cereal rye

– Wheat

– Mustard

– Arugula

– Fallow control

• Low C amendment rates

– Approximately 1 mg C g-1 soil

• Rhizoctonia solani

– Control in ASD treatments not significantly

better than control

• Sclerotinia sclerotiorum

– High sclerotial germination in all treatments

(75 to 100%)

Controlled environment studies

Controlled environment studies

• Pathogens/weeds

– Sclerotium rolfsii

– Yellow nutsedge

• Soil temperatures

– 15 C to 24 C

• C rates

– 1 to 2.7 mg C g-1 soil

• C-source treatments – Untreated control

– Biofumigant control

(Mustard seed meal; 2 t/ac)

– Fallow with dried molasses

(2.5 t/ac)

– Mustard /arugula cover crop

– Mustard/arugula +

molasses

– Cereal rye cover crop

– Cereal rye + molasses

– Crimson clover cover crop

– Hairy Vetch cover crop

– Wheat cover crop

Controlled environment studies

(McCarty, 2012)

(McCarty, 2012)

(McCarty, 2012)

(McCarty, 2012)

Controlled environment studies

• Pathogens/

nematodes

– Fusarium oxysporum

– Southern root-knot

nematode

• Soil temperatures

– 15 C to 25 C

– 25 C to 35 C

– 35 C to 45 C

• C-source treatments – 0 mg C g-1 soil

– 1 mg C g-1 soil

– 2 mg C g-1 soil

– 3 mg C g-1 soil

– 4 mg C g-1 soil

• Mixtures of starch and

glucose

• Amendment rates as high as 4 mg C g-1 soil

may be necessary to control F. oxysporum at

lower soil temperatures

• Unclear whether this holds true for other

pathogens of concern

• Past research of cover crop amendments at

20 to 30 C indicated effectiveness for control

of F. oxysporum, S. rolfsii and M. incognita at

low amendment rates (Butler et al., 2012b)

Controlled environment studies

Objectives

1. Evaluate soil temperature and C

impacts on pathogen and weed control

during ASD (controlled environment)

2. Evaluate C source impacts on

pathogens, weeds, crop performance,

and soil properties in a field experiment

3. Demonstrate ASD methods versus

grower standard chemical controls

Field trial

• Soil texture: clay loam

• Late Mar/early Apr

treatments

• 5-cm irrigation

• Standard black PE

• Tomato and bell pepper

• Soil temperatures 15 to

24 C

• ASD C rates 1.0 to 4.2

mg C g-1 soil

• C-source treatments – Untreated control

– Biofumigant control

(MSM, 2 t/acre)

– Fallow with dried

molasses (2.5 t/acre)

– Mustard /arugula

cover crop mixture

– Mustard/arugula +

molasses

– Cereal rye cover crop

– Cereal rye + molasses

(McCarty, 2012)

(McCarty, 2012)

Field trial

• Initial field studies in TN have been promising

• High accumulations of anaerobic soil

conditions, especially during the second year

of treatments

• In the second year, lower R. solani

populations were observed in several ASD

treatments compared to UTC although only

significantly so with a mustard/arugula cover

crop

Field trial

• Correlation of accumulated anaerobic

conditions to pathogen and weed control was

not observed

• Tomato and bell pepper yields following ASD

treatment generally did not differ significantly

among treatments

• Low pest pressure observed in field

• Additional research field trials in 2013-14

Objectives

1. Evaluate soil temperature and C

impacts on pathogen and weed control

during ASD (controlled environment)

2. Evaluate C source impacts on

pathogens, weeds, crop performance,

and soil properties in a field experiment

3. Demonstrate ASD methods versus

grower standard chemical controls

On-farm trials and demonstrations

On-farm trials and demonstrations

On-farm trials and demonstrations

(photo: D.M. Butler)

On-farm trials and demonstrations

Indicator of reduction in soils (IRIS)

Conclusions

• Optimization of ASD in Tennessee is in

early phases

– C rates at or above 4 mg C g-1 soil likely

needed due to cooler soil temperatures in

spring treatments

– N fertility management post ASD

• Vegetable producers unlikely to see N limitation

• Fertility for strawberry post ASD needs further

research and more active management

Conclusions

• Optimization of ASD in Tennessee is in

early phases

– Indication of increased activity of

Trichoderma spp. post treatment

– Indication of ASD treatment activity against

monocot weeds

– No yield differences observed in vegetables

– Need more research on sites with high pest

pressure

Ongoing work

• Research farm trials with varying C

rates & C:N ratios + fumigant control

• Increased on-farm research &

demonstration activities

• Continued controlled-environment pot

studies

Acknowledgements

• Partial funding by USDA-NIFA grant

2010-51102- 21707

References • D.M. Butler, N. Kokalis-Burelle, J. Muramoto, C. Shennan, T.G. McCollum and

E.N. Rosskopf . 2012a. Impact of anaerobic soil disinfestation combined with soil

solarization on plant–parasitic nematodes and introduced inoculum of soilborne

plant pathogens in raised-bed vegetable production. Crop Protect. 39, 33-40.

• D.M. Butler, E.N. Rosskopf , N Kokalis-Burelle, J.P. Albano, J. Muramoto and C.

Shennan. 2012b. Exploring warm-season cover crops as carbon sources for

anaerobic soil disinfestation (ASD). Plant Soil 355, 149-165.

• D.G. McCarty. 2012. Evaluation of anaerobic soil disinfestation (ASD) as a

fumigant alternative for warm-season vegetable production in Tennessee. M.S.

Thesis, University of Tennessee.

• E.N. Rosskopf, N Kokalis-Burelle, J. Hong, and D.M. Butler. 2012. Status of

ASD development in Florida. Proc. Annual Int. Res. Conference on Methyl Bromide

Alternatives and Emissions Reductions. MBAO, p. 15.1-15.2, .

• C. Shennan, J. Muramoto, G. Baird, O. Daugovish, S. Koike and M. Bolda.

2011. Anaerobic soil disinfestation: California. Proc. Annual Int. Res. Conference on

Methyl Bromide Alternatives and Emissions Reductions. MBAO, p. 44.1-44.4.

• C. Shennan, J. Muramoto, G. Baird, S. Fennimore, S. Koike, M. Bolda, O.

Daugovish, and S. Dara. 2012. Non-fumigant strategies for soilborne disease

control in California strawberry production systems. Proc. Annual Int. Res.

Conference on Methyl Bromide Alternatives and Emissions Reductions. MBAO, p.

16.1-16.4.