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
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
New Zealand wine regions Auckland Northland 36 Gisborne Hawke s Bay Nelson Wairarapa Marlborough Canterbury Central Otago 45 35000 ha Premium quality Exports AU$1.2b
Grapevine leafroll-associated virus 3 GLRaV-3 or leafroll virus No cure; quantity & quality influence Chardonnay clone: AU$145,000/ha.
Regional & block-specific response Primary objective: To develop an integrated management plan to reduce and maintain annual virus incidence at <1%
Gimblett Gravels sub-region 850ha 1 km
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.
Visual symptom identification GLRaV-3 infected Mg deficient ELISA cost = AU$13 per composite test
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
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
Roguing: removing infected vines Virus management... Effective in 6 blocks Ineffective in 2 blocks A third category... Inconclusive results in 5 blocks.
Cumulative vine loss, 2009 to 2015
Consistent application of... Visual symptom identification and Roguing practices Why the contrasting outcomes?
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
Mealybugs/100 vine leaves inspected (400 leaves inspected per block per year) 200 160 120 80 Ineffective 40 0 Effective virus control A C E J N O I * K ** Block ID Residual vines removed 2011* & 2013**
Mealybug management Few mealybugs = effective virus control Mealybug eradication? No Implement... insecticide best practice mealybug monitoring
The New Zealand Institute for Plant & Food Research Limited
The New Zealand Institute for Plant & Food Research Limited
The New Zealand Institute for Plant & Food Research Limited
The New Zealand Institute for Plant & Food Research Limited
By 2014, 90% of new infections were one of the four nearest neighbour vines The New Zealand Institute for Plant & Food Research Limited
Pattern of virus spread observed most frequently? The New Zealand Institute for Plant & Food Research Limited
In 2010, 26% of first vines showed virus symptoms The New Zealand Institute for Plant & Food Research Limited
But as integrated management gained momentum... The New Zealand Institute for Plant & Food Research Limited
...just 5% were symptomatic by 2015 The New Zealand Institute for Plant & Food Research Limited
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
Block-specific response: 2009-2015
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