Assessment of hot water treatment for control of grapevine trunk diseases in nurseries
| dc.contributor.advisor | Halleen, Francois | en_ZA |
| dc.contributor.advisor | Mostert, Lizel | en_ZA |
| dc.contributor.author | Webber, Matthew | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of AgriSciences. Dept. of Plant Pathology. | en_ZA |
| dc.date.accessioned | 2021-12-02T13:00:49Z | |
| dc.date.accessioned | 2022-02-22T10:19:59Z | |
| dc.date.available | 2021-12-02T13:00:49Z | |
| dc.date.issued | 2020-12 | |
| dc.description | Thesis (MScAgric)--Stellenbosch University, 2020. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: Grapevine trunk diseases (GTDs) have been identified as a major factor contributing towards the decline of grapevines. The main GTDs in South Africa, and the pathogen species commonly associated with them, include Petri disease (Phaeomoniella chlamydospora, Phaeoacremonium minimum, Phaeoacremonium parasiticum, Cadophora luteo-olivacea and Pleurostoma richardsiae), Black foot disease (Campylocarpon fasciculare, Campylocarpon pseudofasciculare, Dactylonectria macrodidyma and Ilyonectria. liriodendri), Botryosphaeria canker and dieback (Neofusicoccum australe and Neofusicoccum parvum) and Phomopsis dieback (Diaporthe ampelina). Although GTDs are commonly associated with mature vines in established vineyards, it is of particular concern that planting material supplied by grapevine nurseries may already contain infections. Unfortunately, once infected, there are limited management strategies available to control GTD infections, with chemical and biological controls largely focusing on protection of pruning wounds. Hot water treatment (HWT) has shown to be effective in controlling a wide range of fungal pathogens from grapevines. Until recently, the HWT protocol recommended to South African nurseries was 50°C for 30 min. Although this protocol is already well studied and has shown to be effective against a wide range of GTD pathogens, it is also known that it does not completely eradicate all infections. A new HWT protocol of 50°C for 45 min has, however, been recommended to South African nurseries for the control of Aster Yellows. The effect of this HWT protocol on controlling fungal GTD pathogens has, however, yet to be determined under South African conditions. The aim of this study was, therefore, to determine the effect of HWT (50°C for 45 min) on fungal pathogens associated with GTDS found in South African grapevine nurseries, firstly in vitro, followed by in artificially inoculated rootstock cuttings of Ramsey, Richter 110, US 8- 7, Paulsen 1103 and 143B Mgt. Pathogen species evaluated in this study include Pa. chlamydospora, Pm. minimum, Pm. parasiticum, Ca. luteo-olivacea, Pl. richardsiae (Petri disease), Camp. fasciculare, Camp. pseudofasciculare, I. liriodendri, D. macrodidyma (Black foot disease), N. australe, N. parvum (Botryosphaeria canker and dieback) and D. ampelina (Phomopsis dieback). In vitro results concluded HWT (50°C for 45 min) was able to cause complete inhibition of conidial germination and mycelial growth of all pathogen species associated with Black foot disease, Botryosphaeria canker and dieback and Phomopsis dieback. Pathogens associated with Petri disease were, however, more tolerant of HWT (50°C for 45 min), with Pl. richardsiae identified as the most tolerant species within the disease complex. Of the Petri disease pathogens, Pa. chlamydospora was seen to be the most sensitive to HWT, followed by Ca. luteo-olivacea. A general trend observed for all pathogen species was that conidial germination was more sensitive to HWT than mycelial growth. Additionally, the effect of HWT using water temperatures greater than 50°C were also investigated using pathogen species able to tolerate 50°C. Pleurostoma richardsiae once again showed the highest tolerance to HWT with temperatures of up to 60°C not able to achieve complete control, suggesting HWT is not an effective means for controlling this pathogen. Results from the in vivo experiments concluded, with the exception to Pl. richardsiae, HWT (50°C for 45 min) was highly effective in reducing the presence of the inoculated pathogens, completely inhibiting the recovery of Pa. chlamydospora and Ca. luteo-olivacea from HWTed material. Although HWT did not completely remove the presence of Pm. minimum and Pm. parasiticum, the incidence and severity of which these species were able to be recovered from HWTed cuttings was significantly reduced. The effect of HWT on recovery of Pl. richardsiae was less consistent. The treatment was not able to significantly reduce the incidence of cuttings from which Pl. richardsiae was recovered from, however, was able to significantly reduce the severity of the infections, although inconsistently. Even though HWT (50°C for 45 min) may not eradicate all internal infections, it still provides nurseries a convenient and effective means of controlling a wide range of GTD pathogens in a single application. HWT of grapevine nursery material remains highly recommended and should be used in an integrated approach combined with all other available management strategies for optimal control of GTDs. | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: Wingerd stamsiektes (WSS) is geïdentifiseer as 'n belangrike faktor wat bydra tot die verval van wingerdstokke. Die belangrikste WSS in Suid-Afrika, en die patogeen spesies wat algemeen daarmee geassosieer word, sluit in Petri-siekte (Phaeomoniella chlamydospora, Phaeoacremonium minimum, Phaeoacremonium parasiticum, Cadophora luteo-olivacea en Pleurostoma richardsiae), Swartvoet (Campylocarpon fasciculare, Campylocarpon pseudofasciculare, Dactylonectria macrodidyma en Ilyonectria liriodendri), Botryosphaeria kanker en terugsterwing (Neofusicoccum australe en Neofusicoccum parvum) en Phomopsis terugsterwing (Diaporthe ampelina). Alhoewel WSS algemeen met ouer plante in gevestigde wingerde geassosieer word, is dit veral kommerwekkend dat plantmateriaal wat deur wingerdkwekerye verskaf word, reeds infeksies kan bevat. Ongelukkig, sodra dit besmet is, is daar beperkte bestuurstrategieë beskikbaar om WSS-infeksies te beheer, hetsy met chemiese of biologiese beheermaatreëls wat grootliks op die beskerming van snoeiwonde fokus. Warmwaterbehandeling (WWB) het getoon dat dit effektief is om 'n wye reeks swampatogene van wingerde te beheer. Tot onlangs was die WWB-protokol wat aan Suid- Afrikaanse kwekerye aanbeveel is, 50°C vir 30 min. Alhoewel hierdie protokol reeds goed bestudeer is en getoon het om effektief teen 'n wye reeks WSS patogene te wees, is dit ook bekend dat dit nie alle infeksies heeltemal uitroei nie. ’n Nuwe WWB-protokol van 50°C vir 45 min is egter aan Suid-Afrikaanse kwekerye aanbeveel vir die beheer van Aster Vergeling. Die effek van hierdie WWB-protokol op die beheer van swam-WSS-patogene moet egter nog onder Suid-Afrikaanse toestande bepaal word. Die doel van hierdie studie was dus om die effek van WWB (50°C vir 45 min) op swampatogene geassosieer met WSS wat in Suid-Afrikaanse wingerdkwekerye aangetref word, te bepaal, eerstens in vitro, gevolg deur kunsmatig geïnokuleerde onderstoksteggies van Ramsey, Richter 110, US 8-7, Paulsen 1103 en 143B Mgt. Patogeen spesies wat in hierdie studie geëvalueer is, sluit in Pa. chlamydospora, Pm. minimum, Pm. parasiticum, Ca. luteo-olivacea, Pl. richardsiae (Petri-siekte), Camp. fasciculare, Camp. pseudofasciculare, I. liriodendri, D. macrodidyma (Swartvoet), N. australe, N. parvum (Botryosphaeria kanker en terugsterwing) en D. ampelina (Phomopsis terugsterwing). In vitro resultate het gewys dat WWB (50°C vir 45 min) in staat was om volledige inhibisie van konidia ontkieming en miselium groei van alle patogeen spesies wat geassosieer word met Swartvoet, Botryosphaeria kanker en terugsterwing en Phomopsis terugsterwing te bereik. Patogene wat met Petri-siekte geassosieer word, was egter meer verdraagsaam teenoor WWB (50°C vir 45 min), met Pl. richardsiae geïdentifiseer as die mees verdraagsame spesie binne die siektekompleks. Van die Petri-siekte patogene was Pa. chlamydospora die sensitiefste teenoor WWB, gevolg deur Ca. luteo-olivacea. 'n Algemene neiging wat vir alle patogeen spesies waargeneem is, was dat konidia ontkieming meer sensitief was vir WWB as miselium groei. Daarbenewens is die effek van WWB met watertemperature hoër as 50°C ook ondersoek vir patogeen spesies wat 50°C kon verdra. Pleurostoma richardsiae het weereens die hoogste verdraagsaamheid teenoor WWB getoon met temperature van tot 60°C wat nie volledige beheer kon bereik nie, wat daarop dui dat WWB nie 'n effektiewe manier is om hierdie patogeen te beheer nie. Resultate van die in vivo eksperimente, met die uitsondering van Pl. richardsiae, bevestig dat WWB (50°C vir 45 min) hoogs effektief was om die teenwoordigheid van die geïnokuleerde patogene te verminder, en geen her-isolasie van Pa. chlamydospora en Ca. luteo-olivacea vanuit WWB material. Alhoewel WWB nie die teenwoordigheid van Pm. minimum en Pm. parasiticum totaal verwyder het nie, is die voorkoms en infeksievlakke van hierdie spesies in WWB steggies aansienlik verminder. Die effek van WWB op die her-isolasie van Pl. richardsiae was minder konsekwent. Alhoewel die behandeling nie in staat was om die aantal steggies waaruit Pl. richardsiae geïsoleer is aansienlik te verminder nie, was dit egter in staat om infeksiesvlakke aansienlik te verminder, alhoewel dit nie konsekwent was nie. Alhoewel WWB (50°C vir 45 min) dalk nie alle interne infeksies uitwis nie, bied dit steeds kwekerye 'n gerieflike en doeltreffende manier om 'n wye reeks WSS-patogene in 'n enkele behandeling te beheer. WWB van wingerdkwekerymateriaal bly steeds ‘n sterk aanbeveling en behoort gebruik te word in 'n geïntegreerde benadering gekombineer met alle ander beskikbare bestuurstrategieë vir optimale beheer van WSS. | af_ZA |
| dc.description.version | Masters | en_ZA |
| dc.embargo.lift | 2023-12-29 | |
| dc.embargo.terms | 2023-12-29 | |
| dc.format.extent | vi, 89 pages | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/124249 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.subject.lcsh | Grapes -- Rootstocks | en_ZA |
| dc.subject.lcsh | Grapevine trunk diseases -- Susceptibility | en_ZA |
| dc.subject.lcsh | Hot water treatment | en_ZA |
| dc.subject.lcsh | Pathogenic viruses | en_ZA |
| dc.subject.lcsh | Grapes -- Diseases and pests -- South Africa | en_ZA |
| dc.subject.lcsh | Rootstocks -- Effect of stress on | en_ZA |
| dc.subject.name | UCTD | en_ZA |
| dc.title | Assessment of hot water treatment for control of grapevine trunk diseases in nurseries | en_ZA |
| dc.type | Thesis | en_ZA |