Xylella fastidiosa A biosecurity threat to Australia

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1 Xylella fastidiosa A biosecurity threat to Australia

2 Why we are concerned about Xylella Xylella causes significant environmental and economic impacts, and many commercial and ornamental plant species are susceptible. Every year tests show more plant species are capable of being infected, and it is spreading around the world. Although it is not present in Australia it is of major concern to our plant industries and environment.

3 Overview of Xylella Xylella is known by a number of common names, depending on the host, including: Pierce s disease, California vine disease, Anaheim disease (in grapevine) dwarf (in lucerne), phony disease (in peach) leaf scald (in plum) bacterial leaf scorch (almond, coffee, elm, maple, mulberry, oak, oleander, sycamore) variegated chlorosis (in citrus) wilt (in periwinkle) Only one species, but several subspecies which affect different hosts Accepted names: fastidiosa, multiplex, sandyi, pauca Proposed names: morus, tashke 3

4 Symptoms Xylella may not cause symptoms in all host species and these symptoms can vary between hosts Transmission from asymptomatic to symptomatic hosts is common Infection clogs the infected plant s fluid vessels, blocking movement of water, and killing even a mature tree in 1-2 years Symptoms are easily confused with water stress or the presence of other pathogens, and can include: leaf discoloration/scorching browning and loss of leaves stunting of young shoots gradual reduction in fruit size over time dieback and eventual death of the plant. Source: E. Barnard, invasive.org 4

5 Transmission and infection Xylella is a bacterium that is found only in the fluid vessels (or xylem) of plants It is transmitted by: Moving live planting material Sap sucking insects such as sharpshooters, leafhoppers, aphids and spittlebugs It is NOT transmitted by seeds or mechanically (such as pruning equipment) Greatest impacts are in areas with mild winters 5

6 Well known effective vectors Scientific name Common name(s) Associated host disease Acrogonia terminalis Citrus variegated chlorosis Cicadella viridis Green leafhopper Pierce s disease Dilobopterus costalimai Citrus variegated chlorosis Draeculacephala minerva Green sharpshooter Pierce's disease Graphocephala atropunctata Blue-green sharpshooter Pierce's disease Homalodisca vitripennis Glassy winged sharpshooter Pierce's disease Oncometopia fasciali Citrus variegated chlorosis Philaenus spumarius Spittlebug, meadow froghopper Olive quick decline Xyphon fulgidum Redheaded sharpshooter Pierce's disease Glassy winged sharpshooter, Homalodisca vitripennis Source: C. Ray, invasive.org * note that none of the vectors in this table are known to occur in Australia Blue-green sharpshooter, Graphocephala atropunctata Source: C. Moorehead, invasive.org Meadow froghopper, Philaneus spumarius Source: Wikimedia commons Dilobopterus costalimai Source: A. Cymru, National Museum Wales 6

7 Global distribution Europe: France (including Corsica, under eradication), Italy (under eradication), Germany (under eradication) Asia: Iran (restricted), Taiwan (endemic) North America: Canada, Mexico, USA (endemic, widespread) Central America: Costa Rica, Puerto Rico South America: Argentina (endemic), Brazil (endemic), Paraguay (endemic), Ecuador, Venezuela 7

8 Host range Extremely wide host range could affect a large number of crops, ornamental, and environmental trees constantly expanding as it is discovered on new hosts More than 368 plant species (including nine hybrids) are confirmed hosts, in 279 genera and 91 families Differences in host range exist amongst subspecies and within particular subgroups/genotypes within a subspecies High amount of genetic variability between the subspecies, and new strains may emerge 8

9 Subspecies Subspecies name Host(s) Associated disease(s) Found in Subsp. fastidiosa Subsp. multiplex Alfalfa, almond, grape, maple Almond, blueberry, elm, peach, pigeon grape, plum, sycamore Almond leaf scorch, Pierce s disease of grapevines Phony disease of peach, plum leaf scald North America, Central America, Iran, Taiwan North and South America, France Subsp. pauca Citrus, coffee, olive Citrus variegated chlorosis South America, Italy Subsp. sandyi Oleander Oleander leaf scorch North America Subsp. morus (proposed) Mulberry Mulberry leaf scorch North America Subsp. tashke (proposed) Chitalpa (ornamental hybrid) Pear leaf scorch Pear Pear leaf scorch Taiwan North America Symptoms of plum leaf scald Source: University of Florida Symptoms of citrus variegated chlorosis Source: A. Purcell, invasive.org Symptoms of Pierce s disease on grapevine Source: A. Purcell 9

10 Global situation Xylella has historically existed on grapevines in the Americas, but has in more recent times rapidly expanded host range, crops impacted, and also distribution, including into Europe for the first time.

11 Timeline of events 1880s: Pierce s disease devastates vineyards of Southern California 1974: Almond leaf scorch described 1987: Citrus variegated chlorosis observed in Brazil. Later observed in Argentina 1995: Xylella found to cause coffee leaf scorch in Brazil 1996: Glassy winged sharpshooter is discovered in California, threatening wine regions 2000: Complete genome sequence of Xylella published in Nature Oct 2013: Olive quick decline syndrome in Italy attributed to Xylella Feb 2014: Emergency measures adopted by the European Union Mid 2015: Xylella identified from ornamental plants in France Nov 2015 : Australia implements emergency quarantine measures for Xylella Jul 2016: First detection of Xylella in Germany on oleander 11

12 Impacts High number of unknowns Economic impacts Pierce s disease is costing California $104 million per year 3 major citrus regions had 44-63% of commercial trees with fruit symptoms devastated in 2005 in Brazil and Argentina Plum leaf scorch caused the loss of entire orchards in Brazil and Paraguay within several years after the disease first appeared More than 1 million ancient olive trees have died in Italy The cost of olive oil has increased by 20% across the EU Social Impacts Loss of livelihoods for farmers, and regional identity Death of ornamental and amenity trees susceptible to the bacterium 12

13 Olive decline in Italy Initially unclear cause of a new disease of olives in southern Italy, called Olive Quick Decline Syndrome Thought to be introduced ~ Oct 2013, pathogen identified as Xylella fastidiosa subsp. pauca Century old olive trees which have become a key part of the landscape, economy, and identity of the region have been wiped out Demarcated zones around affected areas in the Province of Lecce, in Apulia region Including buffer zone where all host plants are to be destroyed 13

14 Olive decline in Italy 14

15 Olive decline in Italy 15

16 Olive decline in Italy 16

17 Olive decline in Italy 17

18 What this means for Australia An incursion of Xylella into Australia would place entire industries, our unique native flora, along with important social or heritage trees at risk. Because of this risk, emergency measures have been put in place and a range of preparedness activities initiated. There is no evidence of Xylella being successfully eradicated once it has established with an effective vector.

19 Current status in Australia Australia is absent of Xylella Absent: no pest records (ISPM 8 Determination of pest status in an area) Phytosanitary measures in place to prevent entry Xylella and Homalodisca vitripennis (vector - glassy winged sharpshooter), and other exotic vectors are notifiable pests Reporting systems in place to report any detections No other records indicating the presence of Xylella Australia conducts ongoing surveillance Regardless, we can t afford to be complacent 19

20 Emergency measures Strengthened existing measures over time Nursery stock and plant material coming from risk areas require testing and freedom certification Approved arrangement requirements for off-shore testing and certification of nursery stock from high risk countries Material not meeting requirements may be held and tested in an approved facility for 12 months or nursery stock material may be hot water treated, followed by standard screening arrangements Taken a broad approach to hosts Regulation of 89 plant families since November 2015 High risk countries - all countries in the Americas and Europe, as well as India, Iran, Lebanon, Taiwan and Turkey Low risk countries - includes all countries not identified as high risk Import conditions are available on BICON at: bicon.agriculture.gov.au 20

21 Preparedness The Australian Government Department of Agriculture and Water Resources has initiated a number of activities to build capability: Conducting a pest risk assessment Evaluating import measures for vectors Preparing an economic assessment of potential impact Planning a study tour to the United States Planning an regional symposium later in the year with international experts to share their experiences and knowledge Prioritising Xylella as a surveillance target for the national plant health surveillance program Preparing a contingency plan, through the Department of Economic Development, Jobs, Transport and Resources, Victoria States and territories maintain diagnostic capability and conduct surveillance, and are prepared for an incursion Industries have in place a range of preparedness activities suited to their needs and risks 21

22 Risk mitigation There are no treatments currently available to cure diseased plants in the field Control options Excluding vectors Removing infected plants and alternative hosts Planting tolerant/less susceptible plant varieties Dipping new stock with hot water - 50 C for 45 minute Managing water stress What else can we do On farm biosecurity and awareness Source plant material from high health schemes Report any suspicious symptoms Work with other industries Conduct surveillance - early warning is vital Research into appropriate control and management strategies 22

23 If you suspect a new plant pest, call the Exotic Plant Pest Hotline For further information about Xylella fastidiosa, and other exotic plant pests, please see the following websites: agriculture.gov.au/biosecurity agriculture.vic.gov.au/agriculture/pests-diseases-and-weeds planthealthaustralia.com.au