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Suppression of Botrytis cinerea by antagonists in living, moribund and dead grapevine tissueVolkmann, Anette (Anette Sigrid) 12 1900 (has links)
Thesis (MScAgric)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: Several attempts have been made to reduce Botrytis cinerea grey mould in vineyards and
in storage by means of biological control. However, the so called "silver bullet" approach in
utilising a single antagonist, has its limitations when compared with synthetic fungicides.
Often the antagonist has a limited spectrum of activity and the duration of its effectiveness is
less than that provided by synthetic fungicides. Furthermore, antagonists are more likely to
be effective in preventing initial infection rather than resumption of latent infection.
Therefore, due to the various infection sites in grape bunches utilised by B. cinerea and the
fact that the pathogen can remain latent in the grapevine tissue, it may be possible to obtain
effective control of the pathogen by integrating fungicides and different biological control
agents each aimed at a different site in grape bunches, protecting the bunch at the various
phenological stages of growth and under different micro climatic conditions. In this study the
potential of three fungal antagonists (Glioc/adium roseum, Uloc/adium atrum and
Trichoderma harzianum) and one yeast (Trichosporon pullulans) to colonise different sites in
grape bunches, and to reduce B. cinerea infection, was investigated in commercial vineyards.
As the biological control agents were used in an integrated system, the effect of various
fungicides frequently applied to local vineyards on the organisms was also investigated.
Fungicide trials were conducted taking into account two possible scenarios. Firstly, the
possible effect of fungicides applied to the vineyard after an application of the biological
control agent or shortly before the application of the biocontrol agent. This entailed exposing
the biocontrol agents to relatively low concentrations of the active ingredient of the
fungicides, similar to the residue levels to which these organisms would be exposed under
field conditions. Secondly, the possibility of applying the organisms and the fungicides at the
same time by making use of spray tank mixtures. This meant exposing the biocontrol agents
to relatively high doses of the active ingredient of the various fungicides. Mycelial growth
and germination tests were performed on agar in Petri dishes to determine the effect of
fungicides. It was assumed that if the fungicide effectively inhibits the antagonist at 2.5 !-lg a.Uml, the fungicide and antagonist can not be used in an integrated programme. Based on
this criterium, T harzianum can not be applied to vineyards with penconazole,
mancozeb/metalaxyl, pyrifenox or mancozeb. In addition T harzianum can not be applied as
tank mixtures with iprodione. However, T harzianum can be used in conjunction with
pyrimethanil, folpan, iprodione, fosetyl-Al and copperhydroxide, provided the chemicals and
the antagonist are applied alternately. Gliocladium roseum can not be applied in a tank
mixture with pyrimethanil and penconazole, but can be used on grapevine in conjunction with
penconazole, pyrifenox, pyrimethanil, iprodione and fosetyl-Al. Ulocladium atrum can not
be applied with pyrimethanil and iprodione. Ulocladium atrum can be applied in conjunction
with penconazole, pyrifenox, pyrimethanil, iprodione, fosetyl-Al and mancozeb. The fungus
can be applied in a tank mixture with penconazole and pyrifenox.
The antagonists were applied as conidial suspensions to bunches at various phenological
stages in commercial vineyards planted with the wine grape cultivar Chardonnay in the
Stellenbosch region, or the table grape cultivar Dauphine planted in Paarl region. Bunches
were collected 2 wk after application, surface-sterilised and used for determining antagonist
colonisation and B. cinerea infection at specific sites in the bunches. In Chardonnay, the
antagonists colonised the different sites, but colonisation during the three seasons was
inconsistent and sporadic. Ulocladium atrum and G. roseum colonised floral debris to a
degree in the 1996 season. However, in the 1997 season these two antagonists did not
develop from floral debris. Trichoderma harzianum colonised floral debris extensively in the
1996 season. In the 1997 season colonisation by T harzianum dropped, but unlike G. roseum
and U atrum, T harzianum occurred at a low level in flowers. Ulocladium atrum only
colonised bunches during bloom, and was not found in bunches monitored from pea-size
stage to véraison. This finding suggests that the saprophyte colonised moribund and dead
flower parts occurring in bunches during full bloom to the pre-pea size stage, and is not likely
to be found in living tissue. Gliocladium roseum colonised grape berries and pedicels to
some degree and T harzianum colonised these grape parts extensively. Botrytis cinerea
occurred inconsistently and at low frequencies in the different sites in bunches. It was
therefore not possible to comment on the effectivity of the various antagonists in the three
seasons during which the trials were performed. However, it was noted that, during the peasize
stage in 1996, when high levels of B. cinerea were recorded, T harzianum controlled
these infections in the pedicels more effectively than any other treatment. / AFRIKAANSE OPSOMMING: ONDERDRUKKING VAN BOTRYTIS CINEREA DEUR ANTAGONISTE IN
LEWENDE, AFSTERWENDE EN DOOIE WINGERDWEEFSEL
Die benadering om Botrytis cinerea verrotting van wingerd met behulp van 'n enkele
biologiese beheeragent in plaas van met sintetiese fungisiede te beheer, het sekere
beperkinge. Antagoniste het dikwels 'n beperkte spektrum van aktiwiteit, en die duur van hul
effektiwiteit is minder as dié van fungisiede. Antagoniste is gewoonlik ook minder effektief
in die beheer van latente infeksie. Die patogeen het verder die opsie om druiwetrosse deur
verskillende infeksieweë te koloniseer. Fungisiede kan druiwetrosse beter teen infeksie deur
veelvuldige infeksieweë beskerm as 'n enkele antagonis. In die lig hiervan is die beheer van
die patogeen deur 'n kombinasie van fungisiede en verskillende biologiese beheeragente, wat
elk gemik is om 'n ander infeksiepunt in die druiwe te beskerm, ondersoek. Drie swamagtige
antagoniste (Glioc/adium roseum, Uloc/adium atrum en Trichoderma harzianum) en een gis
(Trichosporon pullulans) is in die ondersoek gebruik.
Voorloper ondersoeke, waar twee moontlike scenarios in ag geneem is, is met fungisiede
uitgevoer. In die eerste scenario is die effek van fungisiede, aangewend op wingerd kort vóór
aanwending van die biologiese beheeragent, of kort ná aanwending, ondersoek. Hierdie
proef het die blootstelling van die biologiese beheeragent aan relatief lae konsentrasies van
die aktiewe bestanddeel van die fungisied, vergelykbaar met residuvlakke waaraan die
organismes onder veldtoestande blootgestel sou word, behels. Tweedens is die moontlikheid
om antagoniste en fungisiede gelyktydig as spuitpompmengsels toe te dien, ondersoek. In
hierdie proef is die biologiese beheeragente aan relatief hoë dosisse van die aktiewe
bestanddeel van verskillende fungisiede blootgestel. Miseliumgroei en ontkiemingstoetse is
op agar in Petribakkies uitgevoer om die effek van die fungisiede te bepaal. As kriterium is
aanvaar dat indien 'n fungisied die antagonis effektief by 2.5J..lglml aktiewe bestanddeel
inhibeer, die fungisied en antagonis nie in 'n geïntegreerde program gebruik kan word nie.
Gebaseer op hierdie kriterium kan T harnzianum nie aangewend word in 'n wingerd wat met
penconazole, mancozeb/metalaxyl, pyrifenox of mancozeb behandel is nie. Ook kan T
harzianum nie in 'n spuitpompmengsel met iprodione aangewend word nie. Trichoderma harzianum kan egter saam met pyrimethanil, folpan, iprodione en fosetyl-Al gebruik word,
mits dié chemikalieë en die antagonis afwisselend aangewend word. Glioc/adium roseum
kan nie in 'n spuitpompmengsel met pyrimethanil en penconazole aangewend word nie, maar
kan saam met penconazole, pyrifenox, pyrimethanil, iprodione en fosetyl-Al gebruik word.
Uloc/adium atrum kan nie saam met pyrimethanil, iprodione en fosetyl-Al gebruik word nie.
Die swam kan wel in 'n spuitpompmengselmet penconazole en pyrifenox aangewend word.
In verdere proewe is die antagoniste as spoorsuspensies op trosse op verskillende
groeistadia in kommersiële wingerde, wat met die wyndruitkultivar Chardonnay of die
tafeldruifkultivar Dauphine aangeplant is, ondersoek. Trossies is twee weke na toediening
versamel, oppervlakkig gesteriliseer en gebruik om vlakke van antagoniskolonisasie en B.
cinerea infeksie op spesifieke nisse in die trosse te bepaal. In die geval van Chardonnay het
die antagoniste die verskillende nisse gekoloniseer, maar die kolonisasie was sporadies en nie
konstant gedurende die drie seisoene van ondersoek nie. Uloc/adium atrum en G. roseum het
blomdeeltjies tot 'n beperkte mate in die 1996 seisoen gekoloniseer, maar nie in die
daaropvolgende seisoen nie. Daarteenoor het T. harzianum blomdeeltjies ekstensief in die
1996 seisoen gekoloniseer, en in 'n beperkte mate in die daaropvolgende seisoen.
Uloc/adium atrum kon nie trosse van ertjiekorrelgrootte tot deurslaan vestig nie. Hierdie
bevinding dui daarop dat die saprofiet afsterwende en dooie blomdeeltjies, wat van volblom
tot ertjiekorrelstadium in die trosse voorkom, koloniseer, maar dat dit nie in lewende weefsel
voorkom nie. Daarteenoor het T. harzianum die verskillende trosdele ekstensief
gekoloniseer. Botrytis cinerea het gedurende die drie seisoene wisselvallig en teen lae
frekwensies in die verskillende nisse in die trosse voorgekom. Dit was gevolglik nie
moontlik om 'n konkrete afleiding oor die effektiwiteit van die verskillende antagoniste as
biobeheeragente van B. cinerea te maak nie.
In die geval van Dauphine was die onderskeie organismes swak koloniseerders van
blomdeeltjies. Trichoderma harizanum kon egter die lewende trosdele koloniseer.
Kolonisasievlakke was laag en was nooit meer as 50% nie. In beide seisoene het die
kolonisasievermoë van T. harzianum drasties ná trostoemaak gedaal. Daarteenoor het beide
G. roseum en U atrum tydens al die ontwikkelingstadia die lewende trosdele swak
gekoloniseer. Botrytis cinerea het ook uiters sporadies en teen baie lae vlakke voorgekom. Die bevindinge het getoon dat klimaatsomstandighede wat in tafeldruifwingerde in die
Wes-Kaap heers, nie geskik is vir die vestiging van die biologiese beheeragente wat in die
studie ondersoek is nie.
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The inoculum ecology of Botrytis cinerea in Rooibos nurseriesSpies, Christoffel, F. J. (Christoffel Frederik Jakobus) 04 1900 (has links)
Thesis (MScAgric)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Grey mould, caused by Botrytis cinerea, is the most important foliar disease of rooibos
seedlings. Although the disease is primarily controlled with applications of fungicides, the
improvement of cultural methods of disease management should lessen this dependence on
chemical control. Such improvements would, however, not be possible without knowledge of
the inoculum sources and dispersal of the pathogen. The aim of this study was to investigate
the inoculum ecology of B. cinerea in rooibos nurseries in order to identify primary sources of
inoculum and to improve the environmentally friendly management of the disease.
The study was conducted in four nurseries over two production seasons (March to July
2003 and 2004). Levels of airborne inoculum of B. cinerea were monitored on a monthly basis
inside and around the nurseries with spore traps. Samples of plant material and organic debris
were taken in the corresponding areas to determine the incidence of plant material infected by
the pathogen and the incidences of grey mould in the nurseries were recorded. Low numbers
of B. cinerea colonies were observed on the spore traps. Similar levels of airborne inoculum
were observed inside and around the nurseries. The incidence of plant material yielding B.
cinerea was higher outside the nurseries than inside, indicating the importance of such
materials as potential sources of inoculum. Since patterns of airborne inoculum observed in
this study confirmed reports of the local dispersal of B. cinerea, the removal of possible hosts
outside the nurseries could aid in the management of grey mould in rooibos nurseries.
Resistance to dicarboximide fungicides is a genetically stable trait in B. cinerea, and
therefore has the potential to be used as a phenotypic marker. This marker can be used to gain
knowledge on the dispersal of B. cinerea inoculum inside and outside rooibos nurseries.
Isolates of B. cinerea collected from the air and from plant material in and around four rooibos
nurseries were assessed for resistance to iprodione at 1 and 3 μg/ml a.i. Some of the isolates
showed resistance to iprodione at 1 μg/ml a.i. However, none of the isolates showed resistance
at 3 μg/ml a.i. iprodione. The initial incidence of dicarboximide-resistance at the nurseries was
slightly higher than expected. As the season progressed, the incidence of iprodione-resistant
isolates decreased towards May, after which an increase was observed towards July. A
relatively high percentage of isolates collected outside the nurseries was found to be dicarboximide-resistant. Two of the nurseries had a significant higher incidence of resistant
isolates on plant material collected inside, than on plant material collected outside the nursery.
However, when looking at resistance levels of airborne isolates, no significant differences were
found in the incidence of resistant isolates sampled inside and outside the four nurseries. The
data indicated the importance of organic debris and seed-borne infections in the survival and
dispersal of dicarboximide-resistant isolates of the pathogen.
With the current emphasis on organic agriculture the knowledge gained in this study
presents valuable possibilities of improving the cultural management of grey mould in rooibos
nurseries. / AFRIKAANSE OPSOMMING: Vaalvrot, veroorsaak deur Botrytis cinerea, is die belangrikste bo-grondse siekte van
rooibossaailinge. Alhoewel die beheer van die siekte hoofsaaklik op die gebruik van
fungisiede berus, behoort die verbetering van verbouingspraktyke hierdie afhanklikheid van
chemiese beheer te verminder. Sulke verbeteringe sal egter slegs moontlik wees indien
voldoende kennis van die inokulumbronne en verspreiding van die patogeen beskikbaar is. Die
doel van hierdie ondersoek was om die inokulum ekologie van B. cinerea in rooibos kwekerye
te ondersoek sodat primêre inokulumbronne opgespoor en omgewingsvriendelike
siektebestuurspraktyke verbeter kan word.
Die ondersoek is in vier kwekerye oor twee produksie seisoene (Maart tot Julie 2003 en
2004) uitgevoer. Vlakke van luggedraagde inokulum van B. cinerea is op ’n maandelikse basis
met behulp van spoorvangers binne en buite die kwekerye gemonitor. Monsters van
plantmateriaal en organiese materiaal is in ooreenstemmende areas geneem om die voorkoms
van B. cinerea geïnfekteerde plantmateriaal vas te stel en die voorkoms van vaalvrot in die
kwekerye is aangeteken. Min B. cinerea kolonies is op die spoorvangers waargeneem.
Soortgelyke vlakke van luggedraagde inokulum is binne en buite die kwekerye waargeneem.
Die hoër voorkoms van B. cinerea geïnfekteerde plantmateriaal buite die kwekerye as binne,
dui op die belang van sulke materiaal as potensiële inokulumbronne. Aangesien die patrone
van luggedraagde inokulum, soos waargeneem in hierdie ondersoek, ander berigte van B.
cinerea se beperkte verspreidingsvermoë bevestig, kan die verwydering van moontlike
alternatiewe gashere buite die kwekerye die bestuur van die siekte binne die kwekerye
verbeter.
Weerstand teen dikarboksimied fungisiede is ’n geneties-stabiele kenmerk in B. cinerea
en het daarom potensiaal om as ’n fenotipiese merker gebruik te word. Hierdie merker kan
gebruik word om kennis aangaande die verspreiding van B. cinerea in en om rooibos kwekerye
in te samel. Botrytis cinerea isolate in lug en op plantmateriaal in en om vier rooibos
kwekerye is gedurende 2003 en 2004 versamel. Die isolate is vir weerstandbiedendheid teen
iprodioon by konsentrasies van 1 en 3 μg/ml aktiewe bestandeel (a.b.) getoets. Isolate met
weerstand teen 1 μg/ml a.b. iprodioon is waargeneem, maar nie teen 3 μg/ml nie. Die aanvanklike voorkoms van dikarboksimiedweerstand by die kwekerye was hoër as verwag.
Hierdie vlak het egter gedaal met die verloop van die seisoen tot in Mei, waarna ’n toename tot
in Julie waargeneem is. Die persentasie dikarboksimied-weerstandbiedende isolate buite die
kwekerye was relatief hoog. In twee van die kwekerye was die voorkoms van
weerstandbiedende isolate op plantmateriaal in die kwekerye betekenisvol hoër as op
plantmateriaal buite die kwekerye. Daar was egter geen betekenisvolle verskille in die
voorkoms van luggedraagde weerstandbiedende isolate nie, ongeag van die kwekery of posisie.
Die data dui op die belang van organiese materiaal en saadgedraagde infeksies in die oorlewing
en verspreiding van dikarboksimied-weerstandbiedende isolate van die patogeen.
Met die huidige klem op organiese landbou bied die inligting wat in hierdie ondersoek
versamel is moontlike praktyke wat geïmplementeer kan word om die beheer van vaalvrot in
kwekerye met behulp van verbouingspraktyke te verbeter.
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Epiphytic yeasts isolated from apple leaves to control of gray and blue mold fruit rots of appleFalconi, Cesar E. 14 June 1996 (has links)
Eight phylloplane yeasts were isolated from backyard apple trees in
Corvallis, OR. Yeast isolates were classified to genus or species level. All
isolates were tested in vitro for antagonistic activity against the postharvest
pathogens Botrytis cinerea and Penicillium expansum. Of these isolates,
Aureobasidium pullulans, Sporobolomyces roseus Rhodotorula sp., consistently
reduced mycelial growth of B. cinerea and P. expansum in nutrient yeast
dextrose agar (pH 4.5 or 7.0) incubated for 8 or 30 days at 24 or 1 C, respectively.
These three yeasts also were evaluated for their ability to suppress spore
germination of B. cinerea and P. expansum in a gradient of apple juice
concentrations and to suppress development of gray and blue mold lesions in
inoculated fruits of Golden Delicious apple. Germination of B. cinerea and P.
expansum was reduced significantly (P���0.05) when incubated with the yeast
isolates in 100 or 50% apple juice, but not in 0, 1 or 10% apple juice. S. roseus
and A. pullulans reduced significantly (P���0.05) the size of gray mold lesions in
wounded fruit stored at 5 C and 24 C by 63 to 72 and 81 to 90%, respectively,
when compared to the nontreated control. Size of blue mold lesions in fruit
stored at 5 and 24 C also were reduced significantly (P���0.05) by 66 to 38 and 74
to 63%, respectively, when pre-treated with S. roseus and A. pullulans. In
general, fruit rot suppression by some yeasts isolated in this study was similar in
magnitude to suppression obtained by Cryptococcus laurentii isolate 87-108, a
yeast with commercial potential to suppress postharvest rots of pome fruits.
Pretreatment of apple wounds with washed cells of A. pullulans, S. roseus,
Rhodotorula sp., resulted in disease suppression, but treatment of wounds with cell-free culture supernatant of these isolates did not affect lesion development. Population size of A. pullulans, S. roseus, and C. laurentii increased in apple wounds incubated at 5 or 24 C for up to 25 days, indicating that they colonized the wound site. Data collected in this study support the hypothesis that yeast isolates antagonize fruit pathogens by competing for nutrients in wounds on fruit surfaces. The isolates of A. pullulans and S. roseus show promise for commercial development. / Graduation date: 1997
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