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Cover crops and compost in vineyards – opportunities for improving soil health
Melanie Weckert
Research Scientist: plant pathology, soil microbiology
National Wine and Grape Industry Centre
Charles Sturt University, Wagga Wagga NSW,
Spring vine health field day, Mudgee 29/7/2010
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Warm climate site at Wagga Wagga, NSW: treatments can be seen clearly before canopy develops. Grasses growing in spring time.
Undervine spray only
Complete spray out
Permanent swards
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The effect of the ‘slash only’ treatment in Wagga (hot, dry, under watered, 2 year drought) was to
over-stress the vines and reduce yield (wrong sort of perennial grasses?).
Slash only
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Tumbarumba - canopies were not as stressed by the ‘slash only’ treatment although vigour was decreased to a useful extent.
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Weeds affect grapevine vigour
• Under-vine and mid-row permanent swards actively
growing in spring) strongly reduced vine vegetative
growth, lower yields (Tesic et al., 2007)
• This can be a good thing if vigour is a problem
• Not so good in hot, dry regions.
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Permanent swards
• Permanent living ground cover is the best for microbes (pasture soils have very high microbial activity and biodiversity).
• Root exudates are important.
• Improved soil structure: lower bulk density.
• Hot Water extractable Carbon (HWC) increased by 73% three years after start of permanent sward.
(Whitelaw-Weckert M.A; Rahman L; Hutton R; Coombes N (2007). Permanent swards increase soil microbial counts in two Australian vineyards. Applied Soil Ecology 36, 224-232. )
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Permanent swards
• Deep rooted winter growing perennial grass swards that die off in spring so do not compete with grapevines for nutrients and water are successful in all climates:
• Prof. Robyn Wood (NWGIC) has had ten year practical experience in establishing these.
• Ground cover catches dew even when it doesn‟t rain.
• Cooler under the vine.
• Plant before autumn break – new plants catch the dew.
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Nine basic steps for maintaining soil structure(Alf Cass, Cockroft and Tisdall, 1993 ASVO Seminar):
·
1. Select the vineyard site with care.
2. Use limited and judicious deep and shallow tillage to loosen soil for root growth and reduce water-logging. (Hilling no longer recommended)
3. Establish an earthworm population and fibrous rooted grasses and other crops and keep the soil surface covered with living and dead vegetation and the root zone filled with dead and living roots at all times.
4. Check pH and chemistry of the soil to determine if lime and/or gypsum are needed and add required fertilisers prior to tillage and deep ripping.
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5. Grow fibrous rooted grasses in the winter. Initially will need to
apply a knockdown spray when it begins to compete with vines
during the growing season to provide an in situ mulch. Later-
will not be needed.
6. Irrigate carefully and appropriately to prevent the root zone
from approaching a condition of saturation.
7. Use mulching combined with periods of drying out of soil beds
to control earthworm activity.
8. Limit vehicular movement to reduce the risk of compaction.
9. Recognise critical periods in the development of the site and in
the annual growth cycle and take precautions to ensure that soil
structure is not damaged at these times.
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Winter perennial rye grass vs straw mulch(Vineyard near Echuca, Victoria)
• Rye grass caused greater macroporosity and greater depth of
soft soil (penetration resistance <1 MPa) than wheat straw.
• The root system of ryegrass stabilised the macroporosity
created during initial tillage and hilling process.
• Wheat straw had more pores of smaller size (including
mesopores, 30–0.2 mm diameter) so greater water content at
field capacity and pre-irrigation.
“Management to increase the depth of soft soil improves
soil conditions and grapevine performance in an irrigated vineyard”
Wheaton AD, McKenzie BM, Tisdall KM, (2008), Soil & Tillage Research 98, 68–80.
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Fibrous roots and AMF(vineyard near Echuca, Victoria)
• Ryegrass roots stabilised disturbed soil.
• Increase in the percentage of water-stable aggregates
was directly related to length of ryegrass roots and the
length of arbuscular mycorrhizal fungal hyphae
associated with ryegrass roots.
• Tisdall and Oades (1979)
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• Electron microscopy study vineyard soil, France. Studied mobile soil organic matter by electron microscope
• Bacteria and clay minerals connected nanoaggregates.
• Then nanoaggregates micro-aggregates.
• Perdrial N, Perdrial JN, Delphin JE, Elsassa F, Liewig N (2010) “Temporal and spatial monitoring of mobile nanoparticles in a vineyard soil: evidence of nanoaggregate formation” European Journal of Soil Science, August 2010, 61, 456–468.
Bacteria - essential for aggregation
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Nano-aggregation in soil pores
P e r d r i a l et al., 2010.Scale bar = 1µm
Clay
minerals
(negatively
charged)
and positive
bridging
ions (e.g.
Ca 2+)
Forms a nano-aggregate
Bacterial extracellular
polysaccharide
polymer (EPS)
negatively charged
More clay particles join the nano-aggregate
(bacterium is now encapsulated – OM stabilised)Two nano-aggregates combine,
covered in EPS.
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Why aggregate stability is important
• Unstable aggregates = poor structure
• Aggregates disintegrate during rainstorms.
• Dispersed soil particles fill surface pores and a hard
physical crust can develop when the soil dries.
• Lower infiltration
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Aggregate stability is important
• Soil aggregate stability is important for low bulk density and high plant available water.
• Aggregates better infiltration.
• An increase of 1mm of moisture storage in soil over 100 ha = 1 ML ($$$)
• Soil bulk density of the herbicided Tumbarumba inter-rowincreased by 6.4% within 3 years.
• Negative correlations - within 3 years, high organic carbon lower bulk density at both Wagga and Tumbarumba.
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How to get poor aggregate stability
• Break down plant organic matter (by cultivation etc)
• Disrupt existing aggregates and fungal hyphae (by cultivation etc)
• Leave soil bare and exposed to the physical impact of raindrops or wind-blown soil particles.
• Use pesticides harmful to beneficial soil microorganisms.
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50 100
1.0
150
1.5
200
2.0
2.5
3.0
3.5
4.0
75 17525 22512550 100
1.0
150
1.5
200
2.0
2.5
3.0
3.5
4.0
75 17525 225125
More fungi under permanent sward
50 100
1.0
150
1.5
200
2.0
2.5
3.0
3.5
4.0
75 17525 225125
Positive correlation between soil fungi and hot water
extractable carbon (HWC = food for microbes) under-vine at
Wagga Wagga (r = 0.91, P < 0.001) (Whitelaw-Weckert et al.,
Applied Soil Ecology 2007)
Fungi
HWC
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Fungi are important for aggregation
Cryo SEM
– fungus
on
grapevine
root hair
Scale bar = 50µm,
Photo M. Weckert
National Wine and Grape Industry Centre is a Partnership between
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2 4 6 8 10 12
20
04
00
60
08
00
10
00
HWC (mg C cm3
ds)
To
tal so
il c
ellu
loly
tic b
acte
ria
(T
CB
)(c
fu c
m3 d
s)
Positive
correlation
between
cellulolytic
bacteria
and soil carbon at
Tumbarumba (r =
0.82, P < 0.001)
(Whitelaw-Weckert et al.,
Applied Soil Ecology 2007)HWC
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Bacteria are important for disease suppression
Bacteria vs
Botryosphaeria
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Eutypa lata
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Colletotrichum acutatum
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Cylindrocarpon macrodidymum
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Wagga field results
0
200
400
600
800
1000
1200
undervine,
herbicide
undervine, nil
herbicide
inter-row, nil
herbicide
inter-row,
herbicide
x 1
04 C
FU
/g d
ry
so
il
----Under-vine--- ----inter-row----
low low low high organic matter
Soil bacteria able to inhibit Cylindrocarpon (in vitro)
7-fold
increase
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Beneficial nematodes increased
• Beneficial nematodesincreased under permanent swards
• Plant parasitic nematodes such as root knot nematode decreased
• Rahman et al., Applied Soil Ecology 2009
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Cultivation – what does it do to the soil?
• Decreases soil organic carbon and soil microbial activity and biodiversity compared to permanent swards (Reuter and Kubiak, 2000).
• Steep slopes and cultivation – erosion.
• Dust, mud (getting bogged)
• Disruption of AMF hyphae.
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Compost
• Marina Alonso‟s PhD project:Chris Penfold‟s plots at
Clare Valley and Langhorne Creek and Marina‟s plots
at CSU Wagga.
• Significantly more cellulolytic bacteria and
pseudomonad bacteria in the soil from plots treated
with grape marc compost than from plots treated with
herbicide
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Grape marc compost (many feeder roots)
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Under bare soil (no feeder roots)
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Close up of feeder roots under grape marc compost
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GlyphosatePhosphoenol pyruvate/erythrose-4-phosphate
shikimic acid
Salicylic acid
phenolics, lignins
Tryptophan Tyrosine
Glyphosate binds
to EPSP synthase
Chorismic acid
Phenylalanine
Auxins
(IAA)Photosynthesis
Shikimic acid
pathway
(plants,
microbes)
Glyphosate
prevents
synthesis of
aromatic
amino acids
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Glyphosate – increased soil-borne fungi
• “The herbicidal efficacy of glyphosate is largely due to colonization of roots of affected plants by soil-borne pathogens” (Johal and Rahe, 1984).
• Non-target plants such as grapevines?
• “glyphosate synergistic interaction” (wheat, Baley et al., 2009)
• Herbicides, weeds had no effect on grapevine AMF (Baumgartner et al., 2010)
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Glyphosate – increased plant disease severity
• Glyphosate causes selected components of the
microbial community to be stimulated while others are
suppressed, resulting in a disruption of soil and root
microbial community composition.
• one of the surfactants commonly included in
glyphosate-containing products, polyoxyethylene
amine, is potentially toxic to microorganisms (Tsui and
Chu, 2003).
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Glyphosate – increased plant disease severity
• Glyphosate decreased fluorescent pseudomonads
(rhizosphere bacteria antagonistic to Fusarium root
pathogens in crops (Kremer and Means, 2009 )
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Effect on Chardonnay, 8 weeks after treatment
Control (no glyphosate) Low glyphosate (0.4 kg a.i./ha
glyphosate as isopropylamine salt)
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With added fungal pathogen
Cylindrocarpon with low herbicide;
„Short stubby roots with few laterals‟
similar to those found on sugarcane,
by Dissanayake et al. (1998).
Inoculated with
Cylindrocarpon,
without herbicide
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Transfer from weeds to vines
• Glyphosate transfers to non-target plants via the
rhizosphere
• Sprayed on weed foliage rapid translocation to roots
stabilised in rhizosphere rots of non-target plants.
(Neumann et al., 2006)
Nitrate
leaching
N fixing(Rhizobium in nodules
of legume Sub clover)
Decomposers (bacteria,
fungi: e.g. Trichoderma)
RNH2
Free living N fixing soil
bacteria (Azospirillum,
nitrogenase)
ammonium (NH4+)
Ammonification
Nitrites (NO2-)
Nitrification
Nitrosifying bacteria
(e.g. Nitrosomonas)
Nitrifying
bacteria
Nitrates (NO3-)
Assimilation
Denitrification e.g.
Pseudomonas
fluorescens in
anaerobic
conditions
N2 or N2O
Atmospheric N2
(e.g. Nitrobacter)
N fixing
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N cycle
• Mutualism: two different species „help each other‟
(both derive a benefit from lifelong association) -
structures within plants not necessary.
• Obligate/facultative mutualistic symbiosis:
– Rhizobium may live in nodules of legumes (facultative
endosymbiotic). Without Rhizobium, legumes become very
low in N (obligate endosymbiotic).
Dissolution-chemical, roots, fungi, bacteria
Decomposers
Plant and animal residues
Organic P - in
microbes, humus
Soil solution P: (HPO4-2) H2PO4
-1
(0.001 mg/L to 1 mg/L)
Fertiliser P
Plant uptake
P in grape harvest
Mineral surfaces:
clays, iron and
aluminium oxides,
carbonates
Secondary
compounds
(CaP, AlP, FeP)
Precipitation
Phosphorus cycle
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Phosphorus cycle
• Obligate/facultative mutualistic symbiosis:
– Arbuscular mycorrhizal fungi live in roots (obligate
endosymbiotic).
– Without AMF, mycorrhizal plants become very low in P.
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AMF in grapevine root tip, Wagga Wagga.
M .Weckert
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AMF arbuscules in grapevine root, Tumbarumba
AMF
arbuscules
in
grapevine
root M. Weckert
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AMF vesicles in grapevine root.
AMF vesicles in
grapevine root (M Weckert)
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Cylindrocarpon – black foot (brown hyphae)
Fungal pathogens in soil
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B
f
Cylindrocarpon
in grapevine root
M. Weckert, CryoSEM
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Cylindrocarpon plus MW555 (Streptomyces sp.
Suppressive bacteria vs fungal pathogens
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Healthy
Chardonnay
roots
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Diseased
Chardonnay
root (young
vine decline)
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Phaeoacremonium aleophilum (black goo)
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Togninia minima (sexual stage of P. aleophilum)
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Phaeomoniella chlamydospora (black goo)
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Macrophomina plus chytrids (pathogens?)
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Pythium irregulare on root (hyaline hyphae, rare septa)
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Rhizoctonia solani on grapevine root
(brown hyphae – note characteristic lateral joins)
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More Rhizoctonia solani on grapevine root
(brown hyphae, some is „monilioid‟)
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Rhizoctonia solani (showing brown hyphae)
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Colletotrichum acutatum
(bitter rot)
Might be found on prunings
in soil?
Pathogens
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Verticillium dahliae
Micro-sclerotia - hyphae are not brown but this
fungus is a root pathogen.
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Botryosphaeria obtusa
(brown hyphae)
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Acknowledgments
• Prof. Robyn Wood: winter growing perennial
grasses.
• Dr. Ron Hutton – floor management field trial
• Dr. Loothfar Rahman – beneficial nematodes
• Lynne Appleby, Rob Lamont - technical
assistance.
National Wine and Grape Industry Centre is a Partnership between
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Selected references
Whitelaw M A (2000). „Growth promotion of plants inoculated with phosphate solubilising fungi,‟ Advances in Agronomy, 69, 99-151.
Whitelaw M A, Harden T J and Bender G L (1997). “Plant growth promotion of wheat inoculated with Penicillium radicum sp. nov.,” Australian Journal of Soil Research, 35, 291-300.
Hocking A D, Whitelaw M A and Harden T J (1998). "Penicillium radicum sp. nov. from the rhizosphere of wheat," Mycological Research 102, 801-806.
Whitelaw M A, Harden T J and Helyar K R (1999). „Phosphate solubilisation in solution culture by the soil fungus Penicillium radicum,‟ Soil Biology & Biochemistry, 31, 655-665.
Whitelaw-Weckert M, Hutton R, Rouse E, Lamont R. (2004). „The effect of herbicides and permanent swards on soil microbial populations in the vineyard.‟ In Supersoil 2004: Program and Abstracts for the 3rd Australian New Zealand Soils Conference, University of Sydney, Australia, 5 – 9 December 2004. (Ed Singh, B) ISBN (Handbook) 1 920842 25 X; ISBN (CD) 1 920842 26 8; ISBN (Web) 1 920842 27 6 www.regional.org.au/au/asssi/supersoil2004
Whitelaw-Weckert M (2004). „In vitro inhibition of grapevine root pathogens by vineyard soil bacteria and actinomycetes‟, in Ophel Keller, K M and Hall, B H (eds), Proceedings of the Third Australasian Soilborne Diseases Symposium. South Australian Research and Development Institute, 8 – 11 February 2004, Adelaide, pp.129-130. ISBN 0-9751880-0-3.
Rogiers S.Y, Whitelaw-Weckert M, Radovanonic-Tesic M, Greer L.A, White R.G, Steel C.C (2005). „Effects of spray adjuvants on grape (Vitis vinifera) berry microflora, epicuticular wax and susceptibility to infection by Botrytis cinerea.‟ Australasian Plant Pathology 34, 221-228.
Whitelaw-Weckert, M.A.; Sergeeva, V.; Priest, M.J. (2006) Botryosphaeria stevensii infection of Pinot Noir grapevines by soil/root transmission. Australasian Plant Pathology, 35, 369-371
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References.Whitelaw-Weckert M.A; Rahman L; Hutton R; Coombes N (2007). Permanent swards increase soil
microbial counts in two Australian vineyards. Applied Soil Ecology 36, 224-232.
Whitelaw-Weckert MA; Nair NG; Lamont R; Alonso M; Priest MJ and Huang R (2007) Root infection of Vitis viniferaby Cylindrocarpon liriodendri in Australia. Australasian Plant Pathology 36, 403-406.
Whitelaw-Weckert MA, 2008. Interactions between Cylindrocarpon macrodidymum, Streptomyces sp. MW555 and Vitis vinifera. International Conference on Biotic Plant Interactions, Brisbane 27-29th March.
Rahman L, Whitelaw-Weckert MA, Hutton RJ, Orchard B (2009) Impact of floor vegetation on the abundance of nematode trophic groups in vineyards. Applied Soil Ecology 42, 96–106.
Whitelaw-Weckert MA, 2009. Biological control of Cylindrocarpon spp. on grapevine roots. Proceedings of the Fifth Australasian Soilborne Diseases Symposium. Thredbo, NSW, 5-7th February 2009.
Rahman L, Whitelaw-Weckert MA, 2009. Association of pathogenic fungi and pest nematodes with young vine decline in Riverina of NSW. Proceedings of the Fifth Australasian Soilborne Diseases Symposium. Thredbo, NSW, 5-7th February 2009.
Rahman L, Whitelaw-Weckert MA. Three consecutive annual applications of brassica green manures suppress root knot nematode (Meloidogyne javanica) and improve vigour and productivity of Semillon grapevine. Submitted Applied Soil Ecology 2010.