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