Can improvement of Soil Health lead to Disease

Suppression?

Koon-Hui Wang, Philip Waisen, Jensen Uyeda, Joshua Silva, Donna Meyer

Jari Sugano, Amjad Ahmad

CTAHR, University of Hawaii at Manoa

Peter Schroder, Wells International School, Bangkok, Thailand

Sustainable Pest

Management LabUniversity of Hawai’i at Mānoa,

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Biofumigation

Oil radish Brown mustard

The use of glucosinolate (GL)-derived isothiocyanate (ITC) from brassica cover crops to suppress soil-borne pests and pathogens (Kirkegaard et al., 1993)

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Seeding: 10 lb/acre

Biofumigation by MTBP(Macerated, Till, cover with Black Plastic)

5 weeks

Flail mower

Till Cover with plastic

(1 week)

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Suppression of root-knot nematodes by MTBP-Biofumigation

• Higher soil sulfate concentration one week after MTBP indicated higher efficacy of

biofumigation of glucosinolate compounds compared to bareground (BG), no-till (NT),

macerated no-till (MNT), no-till with black plastic (NTBP), till (T), and (macerated till).

• Efficacy of MTBP was observed on population of root-knot nematodes in the soil after a

zucchini crops following the mustard treatment.

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Solvita Test

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Solvita Test (Soil Respiration)

6

b

a

ab

-1

0

1

2

3

4

5

6

7

8

C M MW

CO

2b

urs

t

• Biofumigation with brown mustard (M) or brownmustard plus water (MW) increased soil microbialactivities as indicated by higher CO2 burst. Thus,biofumigation increased soil microbial activities.

• But biofumigation did not reduce Fusarium wiltdisease incidence on lettuce.

7 days after biofumigation

Trial 2

Trial 1

Lettuce Biofumigation Test

b

ab

a

0

10

20

30

40

50

60

C M MW%P

lan

t w

ith

Fu

sari

um

Wilt

Trial II

0

5

10

15

C M MW%P

lan

t w

ith

Fu

sari

um

wilt

Trial I

Disease Incidence

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Sulfate as an indicator of biofumigation (7 days after initiation of biofumigation)

7

• Biofumigation with brown mustard (M) was moreefficient in performing biofumigation than MW.

• Biofumigation with brown mustard + water (MW)achieved better green manure effect in Trial II ( =30%) than in Trial I ( = 37%).

• Soil sulfate concentration was negatively related toFusarium wilt incidence in Trial I, and positivelyrelated to number of lettuce plants that survived inTrial II.

Lettuce Biofumigation Test

Lettuce Yield

0

2

4

6

8

10

12

C M MW

Marketable

Unmarketable

Lett

uce

yie

ld(K

g/p

lot)

a

bab

Trial I

0.0

0.5

1.0

1.5

2.0

2.5

C M MW

Lett

uce

yiel

d(K

g/p

lot)

C = Bareground controlM = MustardMW = Mustard + Water

A

B

B

Trial II

0

10

20

30

40

50

60

70

C M MW

Soil

Sulf

ate

(g/

g)

Trial II

-12

-10

-8

-6

-4

-2

0

2

4

6

8

C M MW

SO

42

-co

nce

ntr

atio

n (

g/g)

Trial I

C = Bareground controlM = MustardMW = Mustard + Water

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Soil Drenching of Solution from Organic Materials against Banana Fusarium Wilt

8

BC

ABC

A

ABC ABABC

C

0

2

4

6

8

A L M Sb Sh V W

CO

2lb

/acr

e

Treatments: (5 gal water / plant)

• A = Actinovate (Steptomyces

lydicus),

• L = Lobster meal,

• M = Mustard (ground),

• Sb = Subtilex (Bacillus subtilis),

• Sh = Shrimp shell meal,

• V = Vermicompost tea,

• W = Water

Mustard (ground)Banana root samples on Komada selective medium

Purple colonies were Fusarium colonies.

Lobster meal suppressed Foc, mustard meal increased soil microbial activities.

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Soil Drenching of Solution from Organic Materials on plant-parasitic nematodes and soil health

9

AB

A

B

ABAB AB

AB

0

2000

4000

6000

8000

10000

A L M Sh V W sb

Nem

ato

de/

250

cm3

soil Reniform nematode

B

A

A

ABAB AB

B

0

200

400

600

A L M Sh V W sb

Bacterivorous nematodes

B AB

A

AB

AB

ABB

0

100

200

300

400

A L M Sh V W sb

Fungivorous nematodes

Nem

ato

des

/250

cm

3so

il

• Mustard resulted in lowest abundance of reniform nematodes.

• Lobster and mustard increased bacterivorous and fungivorous nematodes, vermicompost tea increase %

omnivorous nematodes.

• Lobster enhanced bacteria decomposition, mustard enhanced fungal decomposition.

ABAB

B AB

A

AB AB

0

0.2

0.4

0.6

0.8

1

A L M Sh V W sb

%

Omnivorous nematodes

Nem

ato

des

/250

cm

3so

il

(8 weeks after treatment)

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Nematode Suppression

Biofumigation by maceratingmustard residues (17lb FW/plant)followed by drenching H2O toachieve 30% gravimetric soilmoisture (we use 5 gal/plant).

Foc Suppression

Lobster meal mix into water at 35

lb/1000 ft2 soil (here we mix 0.32

lb with 5 gal water per plant).

Soil Health

Brew uncured vermicompost tea >12 hours at 1:100 water, delivered 5 gal/plant.

10

Lobster meal contains chitin, thus

enhance beneficial soil chitin-

feeding microbes, that can dis-

solve cell wall of pathogenic fungi.