The importance and implications of high health planting material for the Australian almond industry by Brendan Rodoni, Mirko Milinkovic and Fiona Constable (Victorian DPI)
Plant viruses and Perennial fruit trees Viruses of almonds in Australia High health planting material Almond and stone fruit biosecurity MT12005: Development of molecular diagnostic tools for exotic and endemic pathogens of Prunus species
Plant viruses and Perennial fruit trees Almonds -Vegetative Propagated crop - Lifespan approx. 20 years Once virus infected, the tree is infected for life The cumulative affects of early virus infection are significant
Virus Transmission by Vegetative Propagation Virus 1 Scion (Budwood) Rootstock Virus 2
Prevention is the best cure Plant clean material Scion (Budwood) Rootstock Repository of high health planting material - mother trees Nurseryman uses high health planting material for propagation Grower plants healthy trees
Viruses of almonds in Australia Prunus necrotic ringspot virus (PNRSV) Prune dwarf virus (PDV) Apple mosaic virus (ApMV) Apple chlorotic leafspot virus (ACLSV) Europe: Mixed infections of ApMV, PDV and PNRSV cause Almond mosaic In Italy average crop losses in 12 major almond cultivars was 25% (2% - 50%) (Martelli and Savino, 1997 Eppo Bulletin 27:525-534) USA: In the USA PNRSV and related strains is the major virus associated with reduced yields
Symptoms associated with virus infected almonds: Symptoms on leaves include: Bright chrome-yellow (calico) pattern Chlorotic discolorations Localised necrosis (shot hole) Leaf curling Additional symptoms include: Bud failure Rosetting Stunting Bushy growth
PNRSV infected Almond tree leaf symptoms: shot hole, leaf curl
Symptoms on young leaves -Leaf curl -Marginal leaf necrosis
Rosetted growth Symptoms on old leaves -Shortened internodes -Bushy appearance -Chlorotic discoloration - Leaf curl
Symptoms expressed on chip bud inoculated GF305 indicators in the screenhouse: - Possible ilarvirus
High Health Planting Material for the Australian Almond Industry Almonds: Industry based - Almond Board of Australia PNRSV, PDV, ACLSV and ApMV 13 viruses, 2 viroids and 4 bacteria are present in Australia and can infect Almond Stone fruit: Individual nurseries with their own specified protocols for pathogen testing (not compulsory) PNRSV, PDV, ACLSV Use of high health material is voluntary
The benefits of high health planting material to the Australian almond industry include: A reliable supply of high health scion and rootstock material for nurseries Provision of planting material to industry that will produce consistent and high yielding trees for the life of the orchard
High health planting material for the Australian almond industry provides an important Biosecurity tool to prevent establishment of new and exotic diseases in Australia You look so hot today Rhonda... Planting healthy trees is like contents insurance for your home
Biosecurity is a priority for the Almond industry Biosecurity is about the protection of livelihoods, lifestyles and the natural environment, which could be harmed by new pest incursions. Biosecurity is a national priority. (Orchard Biosecurity Manual for the Almond Industry ) Safeguard industry production and marketing systems from potential biosecurity threats (Australian Almonds Strategic R&D Plan 2011 2016 Strategy 3.2 ) Industry biosecurity strategies protect industry from risks posed by pests through exclusion, eradication and control (Plant Health Australia)
New and emerging viruses they do occur AIDS - HIV SARS Bird Flu Hendra virus Vic Rail
Plum pox virus Sharka - A serious threat to the Australian almond industry Spain: 800,000 trees destroyed during attempted eradication campaign USA - Over 1000 acres of stone fruit orchard destroyed
Almond and stone fruit biosecurity Natural protection from exotic threats: Geographically isolated No shared land borders. Active protection: National quarantine system. Biosecurity continuum: Offshore: Accredited suppliers Adequate testing Border: Importation Post entry quarantine (PEQ) Illegal importation Onshore: Incursion management Interstate biosecurity Certification Requires rapid validated diagnostic tests for the detection of significant pathogens
Border control: Importing Prunus germplasm into Australia - Constable et al. 2011 HAL project AL10001 Findings: Minimum of two years post entry quarantine (PEQ) testing DAFF-Biosecurity (AQIS) do not currently differentiate between the pathogens that infect different Prunus species The current PEQ list requires updating to include recently described pathogens Pathogen Number of pathogens reported to infect Number of quarantine pathogens Number of quarantine pathogens proposed for Number of quarantine pathogens proposed for Prunus Current Proposed Almonds Stone Fruit Bacteria Many 2 4 3 4 Phytoplasmas or phytoplasma 10 6 10 7 10 groups Viruses 47 13 34 10 34 Viroids 3 1 2 1 2 Fungi Many 70 75 25 50
Industry biosecurity plans: High priority exotic threats Almonds: European stone fruit yellows (Ca. Phytoplasma prunorum) Almond brown line decline, and Almond kernel shrivel (Ca. Phytoplasma pyri) Almond leaf scorch (Xylella fastidiosa) Hyperplastic canker (Pseudomonas amygdali) Summerfruit: Plum pox or Sharka (Plum pox virus) X Disease (X Disease Phytoplasma) Phony peach or Plum leaf scald (Xylella fastidiosa)
MT12005: Development of molecular diagnostic tools to detect endemic and exotic pathogens of Prunus species for Australia (2012-2015) Project Aims: Updated PEQ lists for Prunus species. The development of validated molecular diagnostic tools under Australian conditions Includes surveys to determine incidence and distribution of endemic pathogens and area freedom for exotic pathogens A post entry quarantine diagnostic manual for Prunus species Specific protocols for almonds, summer fruit and cherries. Improved understanding of the genetic variation of PNRSV, PDV, ApMV and ACLSV Improved diagnostic tests for certification Recommendations for optimal pest and disease management strategies for maintaining Prunus budwood repository blocks.
Acknowledgments Horticulture Australia Limited Victorian Department of Primary Industries Almond Board of Australia Summerfruit Australia Mark Whattam (DAFF-Biosecurity)