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Home , Phylloxera, Xylella fastidiosa

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Pierce’s Disease symptoms. Image courtesy of University of . : What do we know and are we ready? Part One

Suzanne McLoughlin, Vinehealth Australia's Technical Manager, analyses the and community’s preparedness and knowledge about Xylella fastidiosa. This is the first in a two-article series on Xylella, which is known to the industry as Pierce’s Disease.

XYLELLA FASTIDIOSA – a gram- Xylella fastidiosa is considered one symptoms – its multiple vectors and its negative, rod-shaped bacterium known of the most harmful plant pathogenic continued global spread. as Pierce’s Disease in , was the in the world and causes death of The pathogen causes clogging of plant subject of an international symposium infected plants. In Australia, Xylella is vessels, resulting in water stress- in Brisbane on May 17-18, organised by our number one priority plant and it’s like symptoms to distal parts of the the Department of Agriculture and Water a high priority pest for the wine industry. grapevine, with vine death in one to two Resources (DAWR). Neither Xylella fastidiosa, nor its highly years post infection. The bacterium is A broad range of international experts efficient vector found in California, the primarily transmitted in the gut of sap- shared their knowledge and experience Glassy-winged , are known sucking and the disease cannot on Xylella with Australian federal and to be in Australia. occur without a vector. state government biosecurity personnel, Xylella is a major threat due to its While Xylella fastidiosa is known as as well as a small number of invited multiple hosts – more than 350 plant Pierce’s Disease in grapevines, it’s known industry participants. species, many of which do not show as many other names in other host plants.

54 It is inherently difficult to control and Pierce’s Disease to cause significant loss the industry, we need to there are no known treatments to cure to the Australian wine industry. look inwardly as a government/industry/ diseased plants. In other countries, it has not simply research collective and ask ourselves a Xylella fastidiosa has been reported on been enough to just have susceptible host range of tough questions: various host crops, either symptomatic or plants, the pathogen (Xylella fastidiosa) • Do we have a culture of strong asymptomatic, in , Central and available vectors – the system is a leadership at the ready or do we have America, , Canada, Iran, far more complex one (as described in an uncoordinated, ‘siloed’ approach to , France, , , and Figure 1). Four key factors are necessary preparedness by government, industry Switzerland [as at 9 May 2017, according and must intersect each other, but a and researchers with stakeholders to the European and Mediterranean Plant range of conditions pertinent to each unclear on roles and responsibilities? Protection Organisation (EPPO) Global key factor must also be present to result • What is our goal for eradication/ Database https://gd.eppo.int/taxon/ in significant vine loss. In Australia, management in the short, medium and XYLEFA/distribution]. Xylella has not we therefore need to be alert but not long term, given our current capacity been detected in any Australian native alarmed. We need to use our time wisely and capabilities, research status and plant species grown overseas. before a potential incursion to vastly available technologies? improve our preparedness capacity and • Do we have scheduled emergency THE FACTORS THAT MUST capability to manage such an incursion. response simulation activities? Are INTERSECT FOR PIERCE’S we recording results and proactively DISEASE TO BECOME A THREAT WHAT CONSTITUTES addressing weaknesses determined? Based on international experience in PREPAREDNESS? • Do we have a prioritised research and the fight against Xylella fastidiosa, a To be prepared to face a Pierce’s extension framework developed by number of key factors must intersect for Disease incursion that would threaten multiple stakeholders, with an agreed

Figure 1. Key factors for Pierce’s disease to be a threat to the Australian wine industry.

55 WHAT HAVE WE LEARNT FROM THE REST OF THE WORLD? Some in-depth, practical presentations were delivered at the symposium from the Californian and Italian viewpoints, outlining their approaches to dealing with Xylella fastidiosa incursions in predominantly grape and hosts, as reported below.

US EXAMPLE The Californian model for management of Pierce’s Disease has been used as a blueprint in the to combat other high priority plant pests. It was realised early on that with limited available research and the relative strength of the Glassy-winged sharpshooter vector, broad-scale disease eradication was not possible in the short- medium term and that, therefore, vector management was the key. Collaboration has been imperative – Glassy-winged sharpshooter. Image courtesy of Reyes Garcia III, USDA Agricultural Research between federal, state, regional, local Service, Bugwood.org. council regulatory and extension staff, multiple industries, researchers, funding model, which outlines high • Which of our laboratories can test nurseries and the public – with roles priority activities key to preparedness? for Xylella fastidiosa and do we have and responsibilities documented and • Do we have readily available access to sufficient surge capacity available? understood by all parties. A strong international resources and expertise? • Can we successfully conduct strain emphasis on communication and • What does our pre-border, border and typing and how long does this take? awareness strategies ensured that the post-border quarantine management Do we have a rapid, accurate, cost- effectiveness of management measures entail? What zones will be put in place effective in-field diagnostic technique were constantly ground-truthed. This and what movements will be allowed which could negate the need to move approach avoided negative social in and out? What disinfestation potentially infected material for backlash, especially from treatment treatments will be required? diagnosis? programs, and even incorporated visits • What will be the surveillance strategies • What are our surveillance strategies for to local schools. within these zones? Would industry early detection and who is responsible Understanding the vector lifecycle representatives be required for for their coordination? Do they differ was crucial. Due to the nature of the surveillance as part of surge capacity for symptomatic and asymptomatic vector, area-wide, cross-sectoral vector following an outbreak? Would there hosts? Will they be cross-sectoral? management was needed, involving be any additional foreseen imposition Have we mapped our land use cover treating the vector in as the on nurseries as has occurred in including riparian areas, in sufficient alternative host where it overwinters, California? resolution? How can we best use before moving into as the • Do we have a communications and our current technologies and what primary host, causing Pierce’s Disease. awareness strategy for industry now emerging technologies could assist? Multifaceted trapping and monitoring and in the event of an incursion? • Do we have a range of effective programs were established to determine • Are we proactively training management options in our toolkit the boundaries of the vector’s location. our personnel both locally and to break the vector lifecycle and/or Federal and state quarantine internationally in field diagnosis, reduce vector populations that have regulations were instituted including surveillance strategies, lab diagnostics been discussed with industry? Which nursery treatment protocols and and social science? of these if any will be mandated in the inspection programs, where all • Do we have a clear understanding event of an incursion? propagation material was inspected for of xylem sap-sucking insects already • Do we have capacity in our nurseries the vector prior to leaving a nursery and in Australia, which could potentially to replace infected vines with less was also inspected upon arrival at the vector the Xylella fastidiosa pathogen, susceptible varieties? destination. and their host plant range? • Will we offer compensation to growers Core to a strong system was an • Do we have readily available, for vine loss and how would this be agreed funding framework by federal, internationally recognised, clear financed? state, industry and regional players guidelines on field sampling? • Have we performed economic analyses for necessary activities, including • Do we have internationally recognised on potential effects of an incursion on containment through quarantine, diagnostic protocols that minimise our industry that have been ground- statewide surveys (trapping, visual false positive and false negative truthed by industry? assessments and biocontrol), public results? awareness campaigns, cultural treatments

56 to primary and alternative hosts (grubbing landscape and then further sub-divided and insecticide spraying), research, and to one hectare resolution for sampling. nursery treatment programs. High resolution (10cm accuracy) remote Federal funding covers many of these sensing RGB-NIRGB imagery is used In Australia, we activities (in the early 2000s US$22m to ‘photo interpret’ and categorise the need to be alert was invested, now around US$15m). A relative health of olive trees as severe, winegrape industry fund (arising from moderate, mild, symptomless or doubtful, but not alarmed. self-assessment contributions from in an attempt to geolocate affected trees We need to use our growers of US$0.75-$2.00 per $1000 for diagnostics, as well as to conduct non- grape value) managed by an industry- biased sampling to survey asymptomatic time wisely before a established Pierce’s Disease/Glassy- trees. potential incursion winged sharpshooter Board, finances While not a failsafe method of to vastly improve research activities and eradication pinpointing olive trees infected with treatments on properties where the vector Xylella (because disease symptoms can our preparedness has not been seen before. Because of the be confused with water stress, salt, capacity and large discrepancy in crop value between fungal and dieback diseases and boron wine and table grapes, only winegrape deficiency), it has merit. Inspectors use capability to manage growers have contributed to the industry an impressive real-time mobile app such an incursion. fund to date. Nurseries self-fund their (Xylpp) in-field to view the geolocation compliance activities. of the tree health maps, allowing them It is important for all Australian to initially inspect low-health trees, prioritised research and extension plan. industries that could potentially aimed at ultimately reducing pathogen We will encourage government to better be affected by Xylella fastidiosa, to spread. Inspectors also log visits share their preparedness plans with our proactively consider their contingency spatially and tag diagnostic samples in industry and ensure industry is updated for funding research, on-ground activities real-time through the app, results of regularly on progress. We believe we are and potential compensation, in the event which can be viewed by other field staff in a strong position to act as a sounding of a local incursion. and laboratories through storage in the board to ensure preparedness plans are XylWeb database. Future technological practically focused and realistic in their ITALIAN EXAMPLE developments include assessing the timeframes and activities. The Italian approach to surveillance applicability of hyperspectral and On a practical note, Vinehealth is for Xylella fastidiosa in in the thermal imagery to assist in early disease currently undertaking the design region, presented a strong use detection, with results to date showing and build of a biosecurity platform to of technology and an integrated track promise. Automatic tree counting is also capture surveillance data and other and trace system for sample collection performed using aerial imagery which biosecurity information critical to from the field to the laboratory. Much can provide updates on tree removal. preparedness and response activities. of the technology presented mirrored Vinehealth also continues its lead role in Australia’s current capacity in pockets, HOW IS VINEHEALTH AUSTRALIA communications and awareness for grape but highlighted our lack of coordinated WORKING TO IMPROVE OUR and wine businesses and stakeholders on national GIS and remote sensing system PREPAREDNESS FOR XYLELLA Xylella and other priority plant pests, to capability necessary in the event of a FASTIDIOSA? ensure greater understanding throughout cross-border incursion. Vinehealth is working hard to keep industry so that informed decisions can Surveillance activities focus on South Australian grape and wine be made by all to prepare for and manage three designated quarantine zones, the businesses free from a range of high a Pierce’s Disease incursion. infected area bounded by a 20 kilometre priority pests and diseases, including containment zone, further bounded Pierce’s Disease and its vectors. We see About Vinehealth Australia by a 10 kilometre buffer zone. In the our role as posing the tough questions to Vinehealth Australia is a statutory buffer zone, one olive tree is sampled per state and federal government and industry authority operating under the hectare and if verified as positive for the bodies to ensure we are jointly on the and Grape Industry Act (1995) with pathogen, then all remaining plants in right path to preparedness. We support legislative powers in South Australia. that hectare recognised as hosts of the and will lobby for strong leadership, a As part of its role, Vinehealth works to Apulian Xylella strain are removed. In coordinated approach between the wine increase the wine industry’s knowledge of both buffer and containment zones, 1,000 industry, government, researchers and biosecurity threats and their management. hectare virtual grids are overlaid over the other stakeholders, and a focused and ww.vinehealth.com.au

VITICULTURE VOLUME 1 – RESOURCES – 2ND EDITION A comprehensive reference book on Australian viticulture devoted to matters that concern pre-planting decisions. AVAILABLE AT Topics include grapegrowing regions of Australia, , climate, grapevine varieties, site selection and berry development and grape quality. www.winetitlesbookstore.com.au

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