The Role & Management of AMF in Vineyards

R. Paul Schreiner

Research Plant Physiologist

USDA – ARS – HCRL

Corvallis, Oregon

What is a Mycorrhiza?• literally means “fungus-root” (Frank 1885)

• recognized as a symbiosis by Pfeffer in 1887

• symbiotic mutualism - both partners benefit

• fungal component is an extension of the plant

root system

Ectomycorrhiza Arbuscular mycorrhiza

Types of Mycorrhizae

• Arbuscular mycorrhiza (AM) - most common,

most ancient, includes most crop plants, fungi are

Glomalean biotrophs, colonize root cells

• Ectomycorrhiza - commonly found in temperate

trees and shrubs, fungi are Basidiomycetes and

saprophytes, form a sheath, colonize between cells

• Ectendomycorrhiza - important in tree seedlings

• Ericoid mycorrhiza - fungi colonize hair-roots of

Heathland plants, Rhododendron, Vaccinium

• Arbutoid / Monotropoid mycorrhiza

• Orchid mycorrhiza

Evolution of Arbuscular Mycorrhizae

400 million year old fossil present day arbuscule

AMF in the roots of the first land plants suggests: AMF

were necessary for plants to colonize primitive soils.

Blair 2009

Why are AMF important in agro-systems?

1. Enhance nutrient uptake (particularly P).

2. Enhance water uptake (drought tolerance).

3. Suppress plant pests / diseases.

4. Stabilize soil aggregates & store soil C.

Size Matters !!

Fine Root & VAM Hyphae

Estimates21 yr-old Pinot noir vines at Woodhall

Length/vine Biomass

Fine Roots 1.8 km 3.78 kg

VAM Hyphae 34,000 km 2.67 kg

Factor = 19,000 X

Why are AMF important in agro-systems?

1. Enhance nutrient uptake (particularly P).

- primarily due to better soil exploration by hyphae

- interaction with soil bacteria (P-solubilizers)

- biochemical mineralization, enzymes ?

2. Enhance water uptake (drought tolerance).

3. Suppress plant pests / diseases.

4. Stabilize soil aggregates & store soil C.

Red Hill SoilsVery Low Soil P

2-15 ppm available P

Huge #’s of Arbuscules in Grape Roots in Red Hill Soils

Grape is a Super-Host for AMF

Effect of Mycorrhizal Fungi on Pinot noir

Grapevines grown in different soils.

NM Control + AMF NM Control + AMF

Mollisol

valley soil

Ultisol

red-hill soil

Impact of AMF on P & K Concentrations

in Pinot noir Shoots

0

0.05

0.1

0.15

Chehalis - Control Chehalis + VAM Jory - Control Jory + VAM

Sh

oo

t P

ho

sp

ho

rus

(%

dry

ma

tte

r)

Shoot P

| | | |

NM +AMF NM +AMF

0

0.4

0.8

1.2

Chehalis - Control Chehalis + VAM Jory - Control Jory + VAM

Sh

oo

t P

ota

ss

ium

(%

dry

ma

tte

r)

Shoot K

| | | |

NM +AMF NM +AMF

Schreiner 2007 Appl. Soil Ecol.

Why are AMF important in agro-systems?

1. Enhance nutrient uptake (particularly P).

2. Enhance water uptake (drought tolerance).

- primarily due to better soil exploration by hyphae

- indirect result of improved plant nutrition

- involvement of plant hormones, other signals?

3. Suppress plant pests / diseases.

4. Stabilize soil aggregates & store soil C.

Ste. Michelle - Canoe Ridge

Vineyard

Cabernet Sauvignon

planted 1989

Deficit Irrigation Trial

1999-2003

vo

lum

e

time

Grape Berry

Development

Irrigation

levels

standard 70% FVETS

standardearly deficit 50% SE

standard late deficit 50% SL

bloom

veraison

I II III harvest

Changes in Arbuscular Colonization of Deficit Irrigated Cabernet Sauvignon

0

10

20

30

40

50

60

70

1/9/01 4/19/01 7/28/01 11/5/01 2/13/02 5/24/02 9/1/02 12/10/02 3/20/03 6/28/03 10/6/03 1/14/04

Sample Date

Arb

us

cu

lar

Co

lon

iza

tio

n (

% r

oo

t le

ng

th)

Control RDI

Early Deficit

Late Deficit

Deficit

Deficit

Deficit

Deficit

Deficit

Deficit

Schreiner et al. 2007

Soil Moisture

1 2 3 4 5 6 7

Y D

ata

2.0

2.5

3.0

3.5

4.0

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

% VAM Colonization

1 2 3 4 5 6 7

Y D

ata

2.0

2.5

3.0

3.5

4.0

50

55

60

65

70

75

80

85

90

% Arbuscules in roots

X Data

1 2 3 4 5 6 7

Y D

ata

2.0

2.5

3.0

3.5

4.0

2

4

6

8

10

12

14

16

18

20

Spatial Analysis: Roots, AMF, & RKN in Chardonnay - E. WA.

AMF - More Prevalent & More

Active in Grapevine Roots

Where Soil Moisture is Lowest

Howland et. al. 2014

Neumann & George 2004

AMF – Enhance P uptake under drought,

but not under well-watered conditions

(Sorghum grown with moderate soil P)

D D

+- +-

Why are AMF important in agro-systems?

1. Enhance nutrient uptake (particularly P).

2. Enhance water uptake (drought tolerance).

3. Suppress plant pests / diseases.

- direct competition with pathogens for root occupancy

- interaction with soil bacteria, changes in rhizosphere

- indirect result of improved plant nutrition

4. Stabilize soil aggregates & store soil C.

Vos et al. 2012

AMF suppressed root knot nematode development in tomato

Photo: Eisenback

Linderman, unpublished

0

20

40

60

80

100

0 7.5 150 750

Initial Ring Nematode Population Density (#/250 cc soil)

Co

lon

iza

tio

n (

%)

%VAM in Fine roots

% Arbuscules in Fine roots

Effect of Ring Nematode on AMF in Pinot noir

Why are AMF important in agro-systems?

1. Enhance nutrient uptake (particularly P).

2. Enhance water uptake (drought tolerance).

3. Suppress plant pests / diseases.

4. Stabilize soil aggregates & store soil C.

- Entanglement of soil particles (better soil exploration)

- Water extraction and re-orientation of clay particles

- Hyphal secretions (polysaccharides, proteins, glomalin)

AMF Are a Key

Component to

Sustainable Ag:

Plants roots have

harnessed the power

of the fungal lifestyle

How Do We Ensure

That AMF Function

Optimally ??Bethlenfalvay

& Linderman

1992

How can we manage mycorrhizal fungi to derive

the maximum benefit in agro-systems?

1. Enhance the existing population in agricultural soils

through proper management practices.

2. Inoculate plants or soils with AM fungi produced on

plants grown elsewhere.

2. When would Inoculation with

AMF be needed in Vineyards ??

• Following Soil Fumigation

– Methyl Bromide, Telone, Metam-Na

• Following Long Fallow Period

– Typically 1 year or longer, completely bare

• Following Lack of AMF Host Plants

– Mustards, Spinach, Buckwheat, Amaranthus &

Lupine

– Oregon - Hazelnuts (ectomycorrhizal host)

combined with clean floor

Field Inoculation Trials 2000-2002

- Walnut Hill

- Woodburn soil, prior grass field

- Temperance Hill

- Nekia soil, grape re-plant

- Woodhall Vineyard (Jory soil)

- King Estate Nursery (Jory soil)

- Doerner’s (Nekia soil)

Summary of AMF Inoculation Trials 2000-02

King Woodhall Temp. Hill Waln. Hill Doerners

Inoculum potential 6.4% 13.0% 4.1% 5.9% 16.2%

Soil P (ppm) 18 13 3 70 8

VAM increase (roots) NO (+) NO YES NO (+) NO(+)

Growth increase NO NO YES NO (+) YES

CONCLUSION: Inoculation of Grapevines is beneficial at sites where

AMF Inoculum Potential & Soil P are both Low.

In Most Cases - Native AMF Populations are

Sufficient to Obtain Healthy Root Colonization

1. Enhancing Native AMF

Populations In Vineyards

• Avoid Long Fallow Periods / Non-hosts

– Maintain AMF Host Plants

– AMF rely entirely on host plant carbon

• Avoid Harmful Chemicals

– Fumigants

– Fungicides

– Readily soluble fertilizers (P! & N)

• Reduce Tillage

– Destroys the soil mycelial network

Long-Fallow Disorder (Australia)Thompson (1987, 1990, 1994) - poor plant growth in grain belt of Australia after

long fallow periods (> 1 year) were due to low AMF propagules in soil.

Thompson 1994 SBBLinseed

Cover Crops!• Provide Numerous Benefits

• The most important Preplant tool to manage

AMF in Vineyards !!

Negative Impacts on Arbuscular Mycorrhizal Fungi

Fumigants

Fungicides

Readily

Soluble

Fertilizers

Impact of Tillage on AMF

• Numerous studies show negative effect

of tillage on AMF, root colonization, and

nutrient uptake

• Effects due to disruption of hyphal

networks in soil

Extensive research - University of Guelph, Penn State, USDA

Evans, Miller, Douds, O’Halloran, Hamel, Kabir, Koide, Addy

Impact of Soil Disturbance on Maize

Site Disturbance Shoot mass

(mg)

Shoot P

(g/kg)

Shoot Zn

(mg/kg)

A None 508 3.1 24

A Tilled 443 1.9 20

B None 478 3.5 23

B Tilled 404 1.2 18

C None 413 2.5 27

C Tilled 312 1.8 20

Evans & Miller 1988

Effect of In-Row Cultivation on AMF In Oregon

Schreiner & Linderman 2005 Sm. Frts. Rev.

Total & Arbuscular

Root Colonization

Reduced by Tillage

Versus Herbicide

Recovery by Veraison

80

Arbuscular Colonization in Pinot noir Roots

1 Year after Alternate Alley Cultivation

Schreiner 2005 Plant & Soil

Farming with Lower Inputs of Chemical

Fertilizers & Pesticides, Water, & Diesel

• A noble goal for everyone, BUT it is not easy.

• Viticulturists are lucky - with respect to fertilizers

(Grapevines have low nutrient requirements and

they love AMF !!).

• Requires More Planning.

• Surely Requires More Monitoring.

– We know what to monitor above ground, just have to

commit to doing it.

– Below ground is still a work in progress (but AMF are

a vital component).