The Role & Management of AMF in Vineyards R. Paul Schreiner Research Plant Physiologist USDA – ARS – HCRL Corvallis, Oregon
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).