soil solarization for control of soilborne diseases (and ...organics.tennessee.edu/pdf/soil...

Craig H. CanadayDept. of Entomology & Plant Pathology

West Tennessee Research and Education CenterJackson, Tennessee

Soil Solarization for Control of Soilborne Diseases

(and Weeds, too)

Some soilborne disease to control

Methods for Control of Soilborne Pathogens

• Biological Seed Treatments– Kodiak Concentrate (Bayer CropScience LP)– Actinovate AG (Natural Industries, Inc.)– Yield Shield (Bayer CropScience LP)– T-22 HC (BioWorks, Inc.)

• Cultural Practices– Resistant varieties– Planting date– Long term crop rotation– Composts, animal manures, and chicken litter– Plant density and row spacing

Soil Solarization

Soilborne Pathogens Controlled by Solarization• Fungi

– Pythium spp.– Rhizoctonia solani– Sclerotium rolfsii– Sclerotinia sclerotiorum– Thielaviopsis basicola– Verticillium dahliae

• Bacteria– Agrobacterium tumefaciens– Streptomyces scabies

• Nematodes– Paratylenchus spp.– Meloidogyne spp.

Soil Solarization

• It’s a preplant method for disinfecting soil for control of soilbornepathogens and weeds

• Involves covering the soil with transparent plastic sheeting during an appropriate summer fallow period

• It captures solar energy and raises the temperatures in the soil to levels lethal to many soilborne pests.

• Moisture is needed to increase the thermal sensitivity of target organisms, improve heat conductivity, and enable biological activity during solarization

• The major commercial use of solarization has been in regions with high solar radiation and high temperatures

West Tennessee Research and Education Center, Jackson, TNTypical Daily Soil Temperatures

35 C = 95 F 40 C = 104 F 45 C = 113 F 50 C = 122 F

First Tennessee Solarization Test - 1989 Creating the “gap” between the layers

Daily Maximum Soil Temperatures 1989

noneblackclearclear / blackclear (gap) clear

Tem

pera

ture

(°C

)

20

25

30

35

40

45

50

55

7/25

7/26

7/27

7/28

7/29

7/30

7/31 8/1 8/2 8/3 8/4 8/5 8/6 8/7 8/8 8/9

35 C = 95 F 40 C = 104 F 45 C = 113 F 50 C = 122 F

noneblackclearclear / blackclear (gap) clear

Tota

l # h

ours

(Jul

y 25

–A

ugus

t 9)

0

50

100

150

200

250

300

350

< 35°C 35- 40°C 40- 45°C 45- 50°C > 50°C

a

bbc

c

db

abb

c aab bc c

d

abb

cd b

abbb

Temperatures at 2" depth from July 25 to Aug 9, 1989

35 C = 95 F 40 C = 104 F 45 C = 113 F 50 C = 122 F

1989 Solarization Test

0

50

100

150

200

250

Treatment

none

clear

clear / black

black

clear (gap)clear

Populations of Pythium spp., 0 – 2 inches

Num

ber c

fu/ g

ram

soi

l

a

a

a

a

b


0

5

10

15

20

25

Treatment

none

clear

clear / black

black

clear (gap)clear

Number of Weeds after Solarization

Num

ber w

eeds

/ 1

kg s

oil a

b b

b b

Second Solarization Test - 1990Overview

Keeping Plastic Sheeting Clean

20

25

30

35

40

45

50

55

60

7/7 7/8 7/9 7/10 7/11 7/12 7/13 7/14 7/15 7/16 7/17 7/18 7/19 7/20

Maximum Soil Temperatures July 7-20, 1990

noneclear (gap) black clear (gap) clear

Tem

pera

ture

(°C

)

35 C = 95 F 40 C = 104 F 45 C = 113 F 50 C = 122 F

20

25

30

35

40

45

50

55

60

7/20 7/21 7/22 7/23 7/24 7/25 7/26 7/27 7/28 7/29 7/30 7/31

Maximum Soil Temperatures July 20-31, 1990

noneclear (gap) black clear (gap) clear

Tem

pera

ture

(°C

)

35 C = 95 F 40 C = 104 F 45 C = 113 F 50 C = 122 F


020406080

100120140160180

Treatment

none

clear

clear + clear

clear (gap)blackclear (gap)clear

Populations of Pythium spp., 0 - 2 inches

Num

ber c

fu/ g

ram

soi

l

a

b b b b


0

50

100

150

200

250

300

Treatment

none

clear

clear + clear



Num

ber c

fu/ g

ram

soi

l

a

b

b b b

What are the benefits of soil solarization for organic gardeners and growers in Tennessee?

Overview of 1993 gardens while solarizing

Creating the “gap” Securing the edges

After 5 ½ weeks Re-setting landscape timbers

Shallow rototilling of the soil Planting Fall Snap Beans, August 3, 1993

1993-94 Solarization Gardens

0

50

100

150

200

250

Treatment

none

clear


Populations of Pythium spp., 0 – 2 inches, 15 September, 1993

Num

ber c

fu/ g

ram

soi

l

a

bb

b

Fall 1993 Snap Beans – Not Solarized

Fall 1993 Snap Beans - Solarized1993 Solarization Gardens

012345678

Treatment

none

clear


Snap Bean Yield, 27 Sep – 8 Oct, 1993

Num

ber k

g / p

lot

a

bb

b

Fall 1993 Spinach – Not Solarized Fall 1993 Spinach - Solarized

1993 Solarization Gardens

0

1.776

3.552

5.328

Treatment

none

clear


Spinach Yield, 10 December, 1993

Num

ber k

g / p

lot

a

a a

b


0100200300400500600700800900

Treatment

none

clear


Weed infestations, 9 November 1993

Num

ber w

eeds

/ m

2

a

b b b


0

0.25

0.5

0.75

1

1.25

1.5

1.75

Treatment

none

clear


Yield Spring Spinach, 6 May 1994

Num

ber k

g / p

lot

a

b

aa

Solarization Gardens – Summer 1994

Solarization Gardens – Summer 1994

Not Solarized Solarized


01020304050607080

Treatment

none

clear


Lima Bean Stand, 1 June 1994

Perc

ent S

tand

a

b

aa


0

1

2

3

4

Treatment

none

clear


Lima Bean Yield, 10 August 1994

Kg d

ry b

eans

/ pl

ot

a

b

a

a


05

1015202530354045

Treatment

none

clear


Yield Summer Squash, 23 June – 9 Aug., 1994

Num

ber k

g / p

lot

a

b

b

a


0

10

20

30

40

Treatment

none

clear


Yield losses to Choanephora Fruit Rot, 23 June – 9 Aug., 1994

Perc

ent L

oss

a

b

a

b

1994 Solarization Gardens - Sweet Corn



0

2

4

6

8

10

Treatment

none

clear


Yield Sweet Corn, 6 July – 2 Aug., 1994

Num

ber k

g / p

lot

a

a

aa

Fall 1994 Gardens



3

4

5

Treatment

none

clear


Yield Fall Spinach, 28 - 30 November 1994

Num

ber k

g / p

lot

a

aa

a


0

20

40

60

80

100

Treatment

none

clear



Num

ber c

fu/ g

ram

soi

l

a

b

b b

2 December 1994

Some Solarization Variations

Research at the Highland Rim Experiment StationSpringfield, TN

1994-96

Bricks for Spacers, Highland Rim Experiment Station

Bricks for Spacers, Highland Rim Experiment Station Bricks & Boards, Highland Rim Experiment Station

Bricks & Boards, Highland Rim Experiment StationHighland Rim Experiment Station

Solarization Research Results – Fall Spinach

0

2

4

6

8

10

Treatment

methyl bromidesolarized

0

10

20

30

40

50

Treatment


0

2

4

6

8

10

Treatment


Pythium (cfu/g)

Yield (lb/plot)% Stand 27 Oct

% Stand 21 Sep

A

B

B

A

NS

0

15

30

45

60

75

Treatment

methyl bromidesolarizedNS

2007 Solarization Experiment

• Three Treatments – each replicated nine times– Control (no plastic)– Black plastic– Clear plastic

• Narrow rows (not plots)

• Rows run North-South

• Measure effects on weeds, vegetable diseases,spinach and broccoli (a transplanted crop) growth & yield

2007 Solarization Experiment – Fall Spinach

01020304050607080

Treatment

noneblackclear

0

10

20

30

40

50

60

Treatment

noneblackclear

0

10

20

30

40

50

60

Treatment

noneblackclear

00.250.5

0.751

1.251.5

1.752

Treatment

noneblackclear

Weeds / sq. ft

Yield (lb/row)% Stand

% Emergence

B

A

A

A

C

B

B

BB

C B

A

2007 Solarization Experiment – Fall Broccoli

0

5

10

15

Treatment

noneblackclear

0

0.1

0.2

0.3

0.4

0.5

Treatment

noneblackclear

Leaf length (cm) Yield (lb/plant)

AAB

B AB AWhen is the best time for soil solarization in Tennessee?

Mean Daily Solar Radiation, 1986-2007, February – NovemberMaximum Daily Soil Temperature, 1986-2007, March-November

(bare soil, two-inch depth)

Twelve Steps for Successful Soil Solarization

1. Plan to solarize a portion of your garden when solar radiation is optimal (June through August).

2. Avoid areas with shadows or north-facing slopes.

3. Rototill the soil to incorporate current weeds, crop residues, compost, fertilizers, etc.

4. Remove any sharp sticks, stalks, etc. that could puncture the plastic.

5. Thoroughly moisten the soil (or wait for a good soaking rain).

6. Cover the moist soil with clear, polyethylene plastic sheeting.

Twelve Steps for Successful Soil Solarization - Continued

7. Bury the edges of the sheeting with soil, landscape timbers, etc. to prevent wind from getting underneath the plastic or hot air from escaping.

8. To achieve the highest solarization temperatures, cover the first sheet with another sheet of clear, polyethylene sheeting. (The first sheet may be black if the second sheet is clear.)

9. If you use two layers, create an air “gap” between the layers of sheeting with strips of insulation, small blocks of wood, bricks, etc. Avoid materials with sharp edges. Bury the edges of the second sheet.

10. Keep the top surface free of dust and water during the solarization period.

11. Remove the plastic after 4 to 6 weeks (perhaps sooner if hot, sunny clear days have been common).

12. When planting your garden, avoid the outer edge (1-2 ft) of the solarizedarea. Avoid rototilling soil deeper than two inches or digging deep holes.

Enjoy a healthier garden with fewer disease problems and fewer weeds!

References1. Soil Solarization by Jaacov Katan and James E. DeVay, 1991, CRC Press, Inc.

2. Soil Solarization for Gardens & Landscapes, University of California Agriculture and Natural Resources, Pest Notes, Publication 74145.

http://www.ipm.ucdavis.edu/PDF/PESTNOTES/pnsoilsolarization.pdf

3. University of California Solarization Informational Websitehttp://solar.uckac.edu/new_page1.htm

4. Soil Solarization – A Nonchemical Method for Controlling Diseases and Pests.http://ceamador.ucdavis.edu/files/942.pdf

5. Soil Solarization for Control of Nematodes and Soilborne Diseaseshttp://www.aces.edu/pubs/docs/A/ANR-0713

6. Solarization for Pest Management in Floridahttp://edis.ifas.ufl.edu/pdffiles/IN/IN82400.pdf

7. Organic Control of White Mold on Soybean, ATTRA Agronomy Technical Note.http://www.attra.org/attra-pub/PDF/whitemold.pdf

AcknowledgmentsThe collaborative assistance of Dr. Jim Wyatt;the technical and field support of Emily Gatch,

Lanny Davis, Mitchell Hatchett, Gordon Percell, and Richard Rosser; and the secretarial assistance of Virginia Stewart

and Angie Thorne are gratefully acknowledged.

Thanks also to the following student workers:Jon Lentz Vicki Meeks John WardJohn Jenkins Jeff Goodson Kary CookMatt Long Sheryl Cantrell Linda HiiRussell Cothran Julie Honeycutt Tamani PercellTony Driesling Beth Sanford Christopher ColemanAndy Reeves Sarah McGee Christie Peterson

Questions?

soil solarization for control of soilborne diseases (and ...organics.tennessee.edu/pdf/soil...

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