Managing grapevine leafroll disease in red berry varieties in New Zealand vineyards

Transcription

1 The New Zealand Institute for Plant & Food Research Limited Managing grapevine leafroll disease in red berry varieties in New Zealand vineyards Vaughn Bell¹, Jim Walker¹, Dan Cohen¹, Arnaud Blouin¹, Phil Lester², Gerhard Pietersen³ Plant & Food Research¹, Victoria University of Wellington, NZ², University of Pretoria, SA³

2 New Zealand Winegrowers research A team with expertise in management, viticulture, research, communications Responsible for funding, planning, study design & data analysis, technology transfer... Simon Hooker Nick Hoskins Ruby Andrew Caine Thompson Gerhard Pietersen

3 New Zealand wine regions Auckland Northland 36 Gisborne Hawke s Bay Nelson Wairarapa Marlborough Canterbury Central Otago ha Premium quality Exports AU$1.2b

4 Grapevine leafroll-associated virus 3 GLRaV-3 or leafroll virus No cure; quantity & quality influence Chardonnay clone: AU$145,000/ha.

5 Regional & block-specific response Primary objective: To develop an integrated management plan to reduce and maintain annual virus incidence at <1%

6 Gimblett Gravels sub-region 850ha 1 km

7 Block-specific study Roguing threshold of up to 20% Study blocks all had virus (range: 4 16%) Objectives 1. Develop a reliable method to identify virusinfected vines in the vineyard (not whites) 2. Determine if roguing could halt virus spread 3. Assess the influence of vector pressure on virus control outcomes.

8 Visual symptom identification GLRaV-3 infected Mg deficient ELISA cost = AU$13 per composite test

9 Enzyme-linked immunosorbent assay A serological diagnostic technique Widely used to screen for GLRaV-3 Detection in the vineyard? A reliable alternative to ELISA that is cost-effective Low risk of over- or under-estimating virus incidence. The New Zealand Institute for Plant & Food Research Limited

10 Visual symptom identification Vines visually identified with GLRaV-3 and ELISA-positive (257 of 263 vines) No foliar symptoms of GLRaV-3 but ELISA-positive (7 of 2,875 vines) Few false positives & false negatives With training, visual diagnostics an effective tool when applied late season. The New Zealand Institute for Plant & Food Research Limited

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12 Roguing: removing infected vines Virus management... Effective in 6 blocks Ineffective in 2 blocks A third category... Inconclusive results in 5 blocks.

13 Cumulative vine loss, 2009 to 2015

14 Consistent application of... Visual symptom identification and Roguing practices Why the contrasting outcomes?

15 Mealybugs: insect vectors of virus 2 species; 3 gen/year Feed on infected Vitis Cryptic lifestyle Mealybug control Biological control Insecticides Top: Longtailed mealybug, Pseudococcus longispinus Right: Citrophilus mealybug, P. calceolariae Dr Rod Bonfiglioli

16 Mealybugs/100 vine leaves inspected (400 leaves inspected per block per year) Ineffective 40 0 Effective virus control A C E J N O I * K ** Block ID Residual vines removed 2011* & 2013**

17 Mealybug management Few mealybugs = effective virus control Mealybug eradication? No Implement... insecticide best practice mealybug monitoring

18 The New Zealand Institute for Plant & Food Research Limited

19 The New Zealand Institute for Plant & Food Research Limited

20 The New Zealand Institute for Plant & Food Research Limited

21 The New Zealand Institute for Plant & Food Research Limited

22 By 2014, 90% of new infections were one of the four nearest neighbour vines The New Zealand Institute for Plant & Food Research Limited

23 Pattern of virus spread observed most frequently? The New Zealand Institute for Plant & Food Research Limited

24 In 2010, 26% of first vines showed virus symptoms The New Zealand Institute for Plant & Food Research Limited

25 But as integrated management gained momentum... The New Zealand Institute for Plant & Food Research Limited

26 ...just 5% were symptomatic by 2015 The New Zealand Institute for Plant & Food Research Limited

27 Roguing in red berry varieties Within 2-3 years of roguing commencing, incidence was <1.0% - an integrated plan Removing symptomatic vines effectively slowed virus spread First vines should be retained Roguing a viable management option. The New Zealand Institute for Plant & Food Research Limited

28 Block-specific response:

29 Acknowledgements New Zealand Winegrowers Ministry for Primary Industries (Sustainable Farming Fund) Vineyard owners & staff ASVO Dr Rod Bonfiglioli. The New Zealand Institute for Plant & Food Research Limited