Quarantine status of selected fungal pathogens on Malus, Prunus and Vitis species

Carstens, Elma (2006-04)

Thesis (MSc)--University of Stellenbosch, 2006.

Thesis

ENGLISH ABSTRACT: Invasions of alien species into non-native environments pose one of the largest, but least addressed international threats to biodiversity, both within natural ecosystems and agricultural settings. It is without exception ranked as the greatest environmental threat of the 21st century. Their introduction and spread have been identified as one of the six major categories of change that could potentially alter the world's biodiversity. The number and variety of species introduced make it clear that it is no exaggeration to state that biological invasions are breaking down biogeographic barriers that created and maintained the major floral and faunal regions of Earth. It is, however, difficult to conceive that a single indicator could measure the impact of an invader on a country due to the difficulty in measuring their environmental as well as their financial impacts. Another contributing factor to this problem is the scarcity of data available on the impact of the thousands of invaders in other countries. For the agricultural sectors, alien invasive species are likened to a two-edged sword: on the one hand they are used in the development of new plant varieties and products and on the other hand they have the potential to threaten agricultural production and as a consequence agricultural economic development. An important challenge for countries lies in the development of improved protocols for the prevention, identification and managing of potential invasive alien species. Plant health has always influenced international trade and the backbone for nondiscriminatory, fair, predictable and transparent international trade is the set of rules that national governments have agreed to follow with the foundation of the World Trade Organisation (WTO) in 1995. With the establishment of the WTO, the "WTO - Agreement on the Application of Sanitary and Phytosanitary measures (WTO-SPS)" also came into force. This agreement lays out the provisions, rights and obligations of countries in setting measures to protect human, animal and plant life and health. It also guides quarantine policy and decision-making, with the objective to prevent the use of quarantine measures by governments as disguised or unjustified trade barriers to protect their agricultural industries from import competition. As a signatory member of the WTO-SPS, South Africa has the right to implement appropriate measures to protect our plant health and environment. To set the appropriate levels for protection, South Africa must either apply to international standards or undertake a scientific based risk analysis process, to justify quarantine measures. These measures must also be the minimum necessary to protect plant health. A key element in negotiations for market access is the provision of a list of regulated pests, as well as a list of all pests associated with the crop within the exporting country, to the trading partners. In this study lists of fungal pathogens associated with Malus spp. and Vitis spp. worldwide, including South Africa, were compiled to enable the National Plant Protection Organisation in South Africa to comply with their responsibilities as a signatory member of the international regulatory bodies and to assist them to safeguard our country against harmful invasive species. It was concluded that to have access to accurate plant health status information, all researchers are summoned to validate new pest records and to submit voucher specimen to our National Collection. Geographical distribution records of pathogens and pests are the basis for phytosanitary decision-making and therefore it is imperative for countries to have access to accurate information regarding the geographical distribution of pathogens within their boundaries. For a pathogen to be classified as an A 1-pest, the pest should be of economic importance to the endangered area and not yet present there or present, but not widely distributed and being officially controlled. Many disputes have arisen during the past years concerning the classification for Monilinia fructicola and Neonectria galligena as A 1- regulated pests for South Africa, due to official records of the presence of these pathogens dating back as early as 1917. The situation was further complicated by recent reports from some European countries that M fructicola was detected on stone fruit imported from South Africa. These issues were resolved in this study by following a molecular approach and guidelines as stipulated by the international regulatory bodies. The absence of M fructicola as well as N galligena from South African stone and pome fruit orchards was confirmed. The regulated status of M fructicola and N galligena in South Africa is therefore scientifically justified.

AFRIKAANSE OPSOMMING: Die inbring van vreemde, skadelike spesies bedreig biodiversiteit binne natuurlike ekosisteme en landbou-omgewings. Hierdie aspek, wat ongelukkig nie die steun of aandag geniet wat dit verdien nie, word sonder uitsondering gereken as die bedreiging vir die omgewing van die 21 ste eeu. Die inbring en verspreiding van hierdie spesies is ook reeds ge1dentifiseer as een van die ses belangrikste potensiele faktore wat tot verandering in die wereld se biodiversiteit kan lei. Statistieke van die aantal en verskeidenheid spesies wat reeds nuwe omgewings suksesvol binnegedring het, is 'n duidelike bewys dat dit geen oordrywing is <lat hierdie verskynsels afbreek maak aan bio-geografiese grense nie, wat tot die ontstaan en instandhouding van die wereld se vemaamste plantegroei- en dierelewestreke gelei het. Die moeilikheidsgraad verbonde aan die bepaling van die impak wat hierdie spesies op omgewings en ekonomiee het, maak dit onmoontlik om 'n enkele indikator te bepaal om hierdie impakte te meet. 'n Verdere bydraende faktor tot hierdie probleem, is die gebrek aan beskikbare data oor die impak wat die menigte van spesies op ander lande gehad het. Hierdie vreemde spesies is vir die landbousektor soos 'n tweesnydende swaard: enersyds word dit benodig vir die ontwikkeling en teling van nuwe kultivars en produkte, en andersyds beskik hul oor die potensiaal om bedreigings vir landbou, en gevolglik ook vir landbou-ekonomiese ontwikkeling, in te hou. Die uitdaging le dus daarin vir lande om riglyne daar te stel en te ontwikkel vir die voorkoming, identifikasie en bestuur van vreemde en potensieel skadelike spesies. Internasionale handel is nog altyd deur die fitosanitere status van plante bemvloed. Die grondbeginsels vir nie-diskriminerende, regverdige, voorspelbare en deursigtige internasionale handel word saamgevat in die stel reels wat nasionale regerings ooreengekom het om te volg met die stigting van die Wereldhandelsorganisasie (WHO) in 1995. Tesame met die stigting van die WHO het die "WTO - Agreement on the Application of Sanitary and Phytosanitary measures" (WTO-SPS) ook van krag geword. Die doel van hierdie ooreenkoms is om riglyne neer te le waarbinne lande moet optree met die daarstelling van maatreels om mens, <lier en plant te beskerm. Dit verskaf ook riglyne vir kwarantynmaatreels en -beleide om sodoende te voorkom <lat lande kwarantynmaatreels kan gebruik as onregverdige handelsbeperkinge om hul eie industriee teen kompetisie te beskerm. As 'n ondertekenaar van die WTO-SPS, beskik Suid-Afrika oor die reg om toepaslike maatreels te implementeer om ons plante en omgewing te beskerm. Om hierdie maatreels te bepaal, moet Suid-Afrika egter aan intemasionale standaarde voldoen of risiko-bepalings uitvoer wat op wetenskaplike beginsels gebaseer is. Hierdie maatreels moet ook die minimum wees wat nodig is om plantgesondheid in Suid-Afrika te beskerm. 'n Sleutelfaktor in die onderhandelingsprosesse vir marktoegang, is die voorsiening van 'n lys van beheerde peste aan die invoerland, asook 'n lys van alle peste en plae wat in die uitvoerland met die gewas geassosieer word, aan die invoerland. In hierdie studie is lyste saamgestel van swampatogene wat wereldwyd met Ma/us en Vitis spp. geassosieer word, insluitende SuidAfrika. Die doelstelling van die lyste is om die Nasionale Plantbeskermingsorganisasie van Suid-Afrika in staat te stel om hul verantwoordelikhede as ondertekenaar van intemasionale ooreenkomste na te kom en sodoende ook ons land teen vreemde en potensieel skadelike spesies te beskerm. Hierdie lyste bied akkurate inligting rakende plantgesondheidstatus in Suid-Afrika, maar <lien ook as werksdokumente vir navorsers wat rekords van nuwe peste moet valideer en ook kulture as bewysstukke in ons Nasionale Versamelings deponeer. Geografiese verspreidingsrekords van patogene en peste vorm die basis van fitosanitere besluitnerning en dit is dus noodsaaklik vir lande om toegang te he tot akkurate inligting met betrekking tot die geografiese verspreiding van patogene binne hul landsgrense. Vir 'n patogeen om as 'n Al-pes geklassifiseer te word, moet die pes van ekonomiese belang wees vir die bedreigde area en nog nie daar voorkom nie, 6f voorkom, maar wel nie wydverspreid nie en amptelik onder beheer is. Verskeie dispute het gedurende die afgelope jare ontstaan rakende die klassifikasie van Monilinia fructicola en Neonectria galligena as Alpeste vir Suid-Afrika as gevolg van amptelike rekords wat vanuit 1917 dateer dat hierdie patogene wel in Suid-Afrika teenwoordig is. Die situasie is verder vererger deur onlangse verslae van Europese lande dat M fructicola op steenvrugte wat vanuit Suid-Afrika ingevoer is, ontdek is. Hierdie probleemgevalle is in hierdie studie aangespreek deur 'n molekulere benadering en riglyne, gebaseer op intemasionale standaarde, te volg. Die afwesigheid van M fructicola en N galligena in Suid-Afrikaanse kern- en steenvrugteboorde is bevestig. Die klassifikasie van M fructicola en N galligena as Al- peste vir Suid-Afrika is dus wetenskaplik geregverdig.

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