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Go to Table of Contents ILYONECTRIA IN GRAPEVINE PROPAGATION NURSERY SOIL IS A CAUSE OF YOUNG VINE DECLINE IN THE RIVERINA M.A. Whitelaw-Weckert A , L. Rahman A A National Wine and Grape Industry Centre, NSW Department of Primary Industries, Charles Sturt University, Wagga Wagga, NSW, Email: melanie.weckert@dpi.nsw.gov.au ABSTRACT. The unexplained deaths of newly planted grapevines is of great economic importance to Riverina wine-grape growers. Vines from the same propagation nursery batches that do not die immediately are often developmentally retarded and usually die within a few years. Characteristic symptoms include very short shoots, low yields and severely stunted roots with black sunken necrotic root lesions. ‘Black goo’ symptoms are absent and the Petri disease fungi not consistently isolated, although members of Botryosphaeriacea are often isolated from below the graft union, both in trunks and roots. In an attempt to determine the cause of young vine decline in the Riverina, NSW, we surveyed 20 affected vineyards. Fungi were isolated from the root system and trunks of six uprooted grafted Chardonnay grapevines from each vineyard. Isolates of two pathogenic Ilyonectria species (cause of ‘black foot’) were isolated from the rootstocks of every diseased grapevine examined. When plants from a propagation nursery supplying the diseased vineyards were sampled, every rootstock stem examined showed disease symptoms. In addition, nursery soil and roots were consistently infected with Ilyonectria. Root inoculation of potted Chardonnay with Ilyonectria isolates from the diseased vineyards resulted in symptoms typical of black-foot disease. We conclude that a major initial cause of young vine decline in the Riverina is infection by Ilyonectria spp. from nursery soil. INTRODUCTION Wine grape-growers in Australia’s Riverina wine region have reported the deaths of many newly planted grapevines. Characteristic symptoms included very short shoots, low yields, severely stunted roots with few feeder roots, black sunken necrotic root lesions and premature death. The objective of this study was to elucidate the pathogens responsible for young vine decline in the Riverina. As the Riverina grapevine roots were severely stunted, we expanded on the earlier Australian investigation (1) by including grapevine roots as well as rootstock trunks, scion trunks and cordons. MATERIALS AND METHODS Vineyard and propagation nursery isolations We conducted an investigation into the incidence of wood and root fungal pathogens from one year-old vines in a propagation nursery and six whole vines from each of 20 Riverina vineyards with young vine decline. Roots and trunk pieces were surface sterilised (3 min 1% chlorine and 3 washes SDW) and plated on Dichloran Rose Bengal Chloramphenicol agar. They were also moist incubated for extended periods. Bait plants Chardonnay bait plants (four replicates) were grown for one year in soil from four sites: (A) adjacent to newly planted diseased vines in vineyard; (B) a ‘diseased’ field site in the nursery supplying the vineyard; (C) soil from site B, sterilised by autoclaving and (D) a healthy field site within the same nursery. Rapid pathogenicity assay on Chardonnay grapevine seedlings Grapevine seeds (Chardonnay) were surface sterilised in 0.5M H 2 O 2 for 24h. The seeds were then washed with SDW three times and soaked for 5 min in 2% hydrogen cyanamide (H 3 NCN, Sigma) to break dormancy. The seeds were planted in sterile potting mix until the seedlings were 4 cm high. They were then dipped for 30 min into a suspension of conidia and mycelium (1 x 10 5 spores mL - 1) of Ilyonectria macrodidyma (DAR81461) isolated from a rootstock trunk from one of the surveyed vineyards. Control plants were dipped in water. The seedlings were planted in sterile potting mix in 1.2 L pots arranged in randomised complete blocks in a glasshouse maintained at 15–25 ◦ C and watered to field capacity. The roots for both the above bait plant and seedling pot experiments were scored for root health and roots and stems were surface sterilised and incubated first on DRBC and then PDA as above. Root and shoot dry weights (50°C until constant weight) were determined. Data were subjected to analysis of variance (anova) test and least significant differences were calculated at P< 0·05 using Genstat for Windows, 8th edition. RESULTS and DISCUSSION I. macrodidyma or I. liriodendri were isolated from 100% of all selected diseased grapevines in the 20 vineyards investigated. In the propagation nursery, every rootstock stem plus the soil and roots investigated were infected with Ilyonectria. Petri disease fungi were isolated from 22% of vineyard vines. Botryosphaeriacea fungi were isolated from 89% of rootstock trunks and our investigations showed that these originated in rootstock mother vine cuttings (data not shown). No pathogens were isolated from the Chardonnay bait plants in (A) vineyard soil, (C) sterilised diseased nursery soil, or (D) healthy nursery soil, but I. macrodidyma was isolated from the nursery soil from the diseased nursery site (B) and the roots were significantly stunted (Table 1). The pathogenicity assay on Chardonnay seedlings showed that, within 5 weeks after inoculation, I. macrodidyma had caused severe root disease symptoms (data not shown). Table 1. Pathogens from Chardonnay bait plant roots. Source of soil Pathogens isolated Root dw (g) (A) Vineyard 0 7.1 a,b (B) Nursery soil from I. 4.0 b ‘diseased’site macrodidyma (C) Sterilised nursery 0 9.7 a soil from ‘diseased’ site (D) Nursery soil from 0 12.5 a second (‘healthy’) site P - 0.033 l.s.d. - 5.4 Values within a column followed by the same letter are not significantly different based on l.s.d. (P=0.05). Conclusion. Two Ilyonectria species, cause of blackfoot in Australia (2) were consistently involved in young vine decline in the Riverina. The high Ilyonectria inoculum level in the nursery field soil is of serious concern for Australian viticulture. ACKNOWLEDGEMENTS The research was supported by the GWRDC. We thank Lynne Appleby for technical support. REFERENCES 1. Edwards, J.and Pascoe I.G ( 2004) Australasian Plant Pathology 33, 273-279. 2. 2. Whitelaw-Weckert, M.A; Nair N.G.; Lamont, R; Alonso M; Priest M.J; Huang, R. (2007). Australasian Plant Pathology 36, 403-406. 7th Australasian Soilborne Diseases Symposium 41
Go to Table of Contents ROOT PATHOGENS DETECTED IN IRRIGATION WATER OF THE ORD RIVER IRRIGATION AREA R.E. Zappia A , D. Hüberli B,C , G.E. St.J. Hardy A,C and K.L. Bayliss A A Cooperative Research Centre for National Plant Biosecurity, Bruce, ACT and School of Biological Sciences and Biotechnology, Murdoch University, 90 South Street, Murdoch, WA, 6150. Australia. Email: R.Zappia@murdoch.edu.au B Department of Agriculture and Food Western Australia, 3 Baron-Hay Court, South Perth, WA, 6151, Australia. C Centre for Phytophthora Science and Management, School of Biological Sciences and Biotechnology, Murdoch University, Murdoch, WA, 6150, Australia. ABSTRACT. Expansion of the Ord River Irrigation Area in Kununurra, Western Australia is currently in progress, and subject to various environmental controls, including the implementation of irrigation tailwater management (recycling) systems. The aim of this research was to determine the presence of plant pathogens in the irrigation water in the irrigation area; and to ascertain what impact they could have if tailwater is recycled. Surveys were conducted during the 2010 and 2011 dry seasons to determine the presence of Phytophthora and Pythium species in the irrigation water and the pathogenicity of isolated species was assessed against two commercial crops – butternut pumpkin and chia. Several pathogenic isolates caused damping-off or distorted primary and lateral root growth. These preliminary findings demonstrate the presence of plant pathogens in the irrigation water, and the need for further investigation to assist with their management in the tailwater. INTRODUCTION The existence of plant pathogens in irrigation water has been reported from irrigation systems worldwide in both supply and tailwater (drains) (1). The Environmental Risk Management Plan (ERMP) for the Ord River Irrigation Area (ORIA) expansion proposes a tailwater management system that will require tailwater to be captured on-site and returned to the farm for application to the crop. Some Phytophthora species, notorious root and collar rot pathogens, have been previously isolated in the ORIA. The aim of this research was to determine the presence of Phytophthora and Pythium species in the irrigation water of the ORIA; and to ascertain what impact they could have on biosecurity in the region if tailwater is recycled. MATERIALS AND METHODS Surveys were conducted during the 2010 and 2011 dry season in Kununurra, Western Australia. Triplicate, 1 L surface water irrigation samples (
Page 2 and 3:
The following organisations sponsor
Page 4 and 5: Welcome to the Seventh Australasian
Page 6 and 7: 7 th Australasian Soilborne Disease
Page 8 and 9: THURSDAY 20 SEPTEMBER 08:30 Chair -
Page 10 and 11: TABLE OF CONTENTS KEYNOTE SPEAKERS
Page 12 and 13: ANTI-FUNGAL METABOLITES PRODUCED BY
Page 14 and 15: Go to Table of Contents KEYNOTE SPE
Page 16 and 17: Go to Table of Contents BENEFICIAL
Page 18 and 19: Go to Table of Contents PENFLUFEN:
Page 20 and 21: Go to Table of Contents THE ROLE OF
Page 22 and 23: Go to Table of Contents NEMATODE BI
Page 24 and 25: Go to Table of Contents CAN EARTHWO
Page 26 and 27: Go to Table of Contents SUSTAINABLE
Page 28 and 29: Go to Table of Contents EFFECTS OF
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Page 32 and 33: Go to Table of Contents CONTAINMENT
Page 34 and 35: Go to Table of Contents COMPARISON
Page 36 and 37: Go to Table of Contents EFFECT OF S
Page 38 and 39: Go to Table of Contents EFFECT OF T
Page 40 and 41: Go to Table of Contents USING MODEL
Page 42 and 43: Go to Table of Contents STRATEGIES
Page 44 and 45: Go to Table of Contents STRATEGIES
Page 46 and 47: Go to Table of Contents THE INTERAC
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Page 50 and 51: Go to Table of Contents EFFECT OF G
Page 52 and 53: Go to Table of Contents DOES PLANTI
Page 56 and 57: Go to Table of Contents ANTI-FUNGAL
Page 58 and 59: Go to Table of Contents RHIZOCTONIA
Page 60 and 61: Go to Table of Contents THE NEMATOD
Page 62 and 63: Go to Table of Contents SEED POTATO
Page 64 and 65: Go to Table of Contents APPLICATION
Page 66 and 67: Go to Table of Contents EVALUATION
Page 68 and 69: Go to Table of Contents MANAGEMENT
Page 70 and 71: Go to Table of Contents DISTRIBUTIO
Page 72 and 73: Go to Table of Contents FISHING FOR
Page 74 and 75: Go to Table of Contents YIELD RESPO
Page 76 and 77: Go to Table of Contents FREE LIVING
Page 78 and 79: Go to Table of Contents A PITCH FOR
Page 80 and 81: Go to Table of Contents WHAT IS THE
Page 82 and 83: Go to Table of Contents SIMULTANEOU
Page 84 and 85: Go to Table of Contents THE PATHOGE
Page 86 and 87: Go to Table of Contents ASSESSMENT
Page 88 and 89: Go to Table of Contents BREAK CROPS
Page 90 and 91: Go to Table of Contents POPULATION
Page 92: Go to Table of Contents Miyan, S. 2
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