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Epidemiology and etiology of Neofabraea species causing lenticel decay of pome fruit in the Western Cape of South Africa
Thesis (MScAgric)--Stellenbosch University, 2015.
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Stellenbosch : Stellenbosch University
2015
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| access_status_str | Open Access |
| author | Rochefort, Jessica |
| author2 | Lennox, Cheryl |
| author_browse | Lennox, Cheryl Rochefort, Jessica |
| author_facet | Lennox, Cheryl Rochefort, Jessica |
| author_sort | Rochefort, Jessica |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MScAgric)--Stellenbosch University, 2015. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/97760 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
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| publishDate | 2015 |
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| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
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| spelling | oai:scholar.sun.ac.za:10019.1/97760 Epidemiology and etiology of Neofabraea species causing lenticel decay of pome fruit in the Western Cape of South Africa Rochefort, Jessica Lennox, Cheryl Den Breeyen, Alana Stellenbosch University. Faculty of AgriSciences. Dept. of Plant Pathology. Neofabraea -- Pathogenesis Fungal gene expression Apples -- Postharvest diseases and injuries Pome fruits -- Diseases and pests Lenticels Fruit -- Diseases and pests -- Biological control -- South Africa -- Western Cape Pears -- Diseases and pests UCTD Thesis (MScAgric)--Stellenbosch University, 2015. ENGLISH ABSTRACT: In the fungal genus Neofabraea, four species are known to affect apple and pear worldwide, namely: N. alba, N. perennans, N. malicorticis and N. kienholzii. These species are a disease complex sharing similar symptoms, morphology, hosts and can occur in the same pome fruit growing region. This disease complex can cause bark cankers on the trunk, limbs and pruning wounds of the tree and postharvest fruit rot from latent lenticel infections. This type of postharvest rot is also colloquially referred to as ‘bull’s eye rot’ from the target-like appearance of alternating brown and dark brown concentric decay rings. In South Africa, only N. alba has been identified to cause bull’s eye rot of apple and is responsible for major losses in the late maturing ‘Cripps Pink’ apple variety in the Western Cape. As very little information is available on N. alba and its epidemiology in South African orchards, producers and packhouses struggle to effectively control this pathogen. This study therefore aimed to add knowledge of N. alba on ‘Cripps Pink’ apple in order to contribute to, and improve the current management strategy of this pathogen. A rapid molecular detection method was developed and ‘Cripps Pink’ apples were screened in 2011, 2012 and 2013 from two orchards, one in the Witzenberg Valley and the other in Grabouw. Neofabraea alba was detected sporadically on the surfaces of ‘Cripps Pink’ apple in each season in both orchards, with increased frequency at harvest in autumn. Cankers were not observed in ‘Cripps Pink’ orchards and N. alba was not detected on plant materials from the orchard floor. Surprisingly, conidia of N. kienholzii and N. perennans were detected on the surface of ‘Cripps Pink’ apples in spring of 2013. Neofabraea kienholzii was detected in November at Grabouw orchard and N. perennans in December at the Witzenberg Valley and Grabouw orchards. Postharvest evaluations of ‘Cripps Pink’ apples from these two orchards in 2013 found N. alba to be the causal species of bull’s eye rot, not N. perennans or N. kienholzii. Further postharvest investigations of ‘Cripps Pink’ apple collected at harvest for three consecutive seasons from producers in the Witzenberg Valley, Ceres, Grabouw, Elgin and the Hemel-en-Aarde Valley found that N. alba was the causal agent of bull’s eye rot. This pathogen was present in the five growing regions with decay incidences ranging between 0 to 73% in 2010, 0 to 6% in 2011 and 0 to 30% in 2012. Currently, there are no fungicides registered for specific use against N. alba of apple in South Africa. In vitro mycelial sensitivity assays of the phenyl pyrrole fludioxonil and anilinopyrimidine pyrimethanil on a N. alba population from ‘Cripps Pink’ apple indicated fludioxonil to have no effect on the growth of the pathogen whereas the majority of isolates were sensitive to pyrimethanil. For pyrimethanil, a mean EC₅₀-value of 6.69 mg/ L was calculated and ranged between 0.93 mg/ L and 56.6 mg/ L. Several N. alba isolates (N=8) were capable of growing on concentrations above 50 mg/ L pyrimethanil, indicating a possible shift in sensitivity. A preliminary study on the presence of bull’s eye rot on pear found the species N. alba, N. perennans and N. kienholzii to be present on two pear varieties in the Western Cape. Neofabraea alba and N. perennans were detected on ‘Packham’s Triumph’ pears in the Witzenberg Valley and Grabouw, respectively. Neofabraea kienholzii was identified from decay on ‘Packham’s Triumph’ and ‘Golden Russet Bosc’ pears in the Witzenberg Valley. Interestingly, N. alba was detected on the surface of the ‘Golden Russet Bosc’ in the same fruit lot affected by N. kienholzii. This is the first report of bull’s eye rot on pear in the Western Cape and the first report of N. perennans and N. kienholzii in South Africa. The source, incidence and control of bull’s eye rot of pears needs to be investigated as these findings have a phytosanitary implication for the management of pears and its export from South Africa. AFRIKAANSE OPSOMMING: In die swamgenus Neofabraea, affekteer vier spesies appels en pere wêreldwyd, naamlik: N. alba, N. perennans, N. malicorticis en N. kienholzii. Hierdie vier spesies vorm ‘n siektekompleks wat soortgelyke morfologie het, simptome veroorsaak, gashere deel en in dieselfde kernvrug-verbouende streke kan voorkom. Hierdie siektekompleks is in staat om kankers op die bas van die stam, takke, lote en snoeiwonde van ‘n boom te veroorsaak, asook na-oes vrugteverrotting vanaf latente lentisel-infeksies. Hierdie tipe na-oes verrotting staan as ‘bull’s eye‘ vrot bekend, weens die teiken-agtige voorkoms van afwissellende bruin en donkerbruin konsentriese weefselvervalringe. In Suid-Afrika, is net N. alba geïdentifiseer as die oorsaak van lentiselverrotting op appels, en is vir groot verliese in die láát ryp ‘Cripps Pink’ appelsoort in die Wes-Kaap verantwoordelik. Min inligting is oor die etiologie en epidemiologie van N. alba in Suid- Afrikaanse appelboorde beskikbaar, gevolglik sukkel produsente en pakhuise om hierdie patogeen effektief te beheer. Hierdie studie se doelwit was om kennis van N. alba op ‘Cripps Pink’ appel in te win om sodoende by te dra tot verbeteringe in die huidige bestuur van hierdie siekte. Eerstens is ‘n molekulêre metode ontwikkel om N. alba vinnig op ‘Cripps Pink’ appels gedurende die groeiseisoen op te spoor. In 2011, 2012 en 2013 is N. alba spore sporadies elke seisoen op die oppervlak van die appels waargeneem, met ‘n verhoogde frekwensie gedurende oestyd in die herfs. Kankers is ‘n belangrike bron van inokulum vir infeksie, maar is nie in die betrokke appelboorde waargeneem waar vrugte getoets is nie. Daarby is N. alba ook nie op plantmateriaal vanaf die boordvloer waargeneem nie. Verbasend genoeg, is spore van N. perennans en N. kienholzii op die oppervlak van die ‘Cripps Pink’ appels in die lente van 2013 waargeneem. Neofabraea kienholzii is in November in die Grabouw boord, en N. perennans in Desember in die Witzenbergvallei en Grabouw boorde waargeneem. Na- oes evaluering van die appels vanuit hierdie twee boorde het getoon dat N. alba die oorsaak van lentiselverrotting was, en nie N. perennans of N. kienholzii nie. Verdere na-oes ondersoeke van 'Cripps Pink’ appels wat tydens oes vir drie opeenvolgende seisoene uit die Witzenbergvallei, Ceres, Grabouw, Elgin en Hemel-en-Aarde-vallei ingesamel is, het getoon dat net N. alba lentiselverrotting veroorsaak het. Hierdie patogeen was in al vyf streke teenwoordig, met verrottingsvoorvalle van 0 tot 73% in 2010, 0 tot 6% in 2011, en 0 tot 30% in 2012. Daar is tans geen swamdoders spesifiek vir gebruik teen N. alba verrotting van appels in Suid-Afrika geregistreer nie. In vitro miselium sensitiwiteitstoetse met die fungisiede fenielpirrool (fludioksoniel) en anilinopirimidien (pirimetaniel) op ‘n N. alba populasie van ‘Cripps Pink’ appels, het aangedui dat fludioksoniel geen effek op die groei van die populasie gehad het nie, terwyl die meerderheid van die isolate sensitief vir pirimetaniel was. Die gemiddelde EC₅₀-waarde vir pirimetaniel is as 6.69 mg/ L bereken, en het tussen 0.93 mg/ L en 56.6 mg/ L gewissel. Verskeie N. alba isolate was in staat om by konsentrasies hoër as 50 mg/ L piremetaniel te groei, en dui op ‘n moontlike verskuiwing in die sensitiwiteitsprofiel van die N. alba populasie. ‘n Voorlopige studie is op die moontlike teenwoordigheid van lentiselverrotting op pere in Suid-Afrika gedoen. Daar is gevind dat die spesies N. alba, N. perennans en N. kienholzii op twee peer variëteite in die Wes-Kaap teenwoordig was. Neofabraea alba en N. perennans is op ‘Packham’s Triumph’ pere onderskeidelik in die Witzenbergvallei en Grabouw-area waargeneem. Neofabraea kienholzii is vanaf weefselverrotting in ‘Packham’s Triumph’ en ‘Golden Russet Bosc’ pere in die Witzenbergvallei geïdentifiseer. ‘n Interressante waarneming was die teenwoordigheid van N. alba spore op die oppervlak van ‘Golden Russet Bosc’, waar net N. kienholzii geïdentifiseer was van verrotte weefsel ná die opberging van die vrugte. Hierdie studie lewer die eerste verslag van lentiselverrotting op pere in die Wes-Kaap en is ook die eerste waarneming van N. perennans en N. kienholzii in Suid-Afrika. Die bron, voorkoms en beheer van N. alba, N. perennans en N. kienholzii moet nog nagevors word, aangesien hierdie spesies ‘n fitosanitêre risiko vir die peerbedryf van Suid-Afrika, in terme van beheerstrategieë en uitvoer vanuit Suid-Afrika, inhou. Masters 2015-12-14T07:42:11Z 2016-12-30T03:00:04Z 2015-12 Thesis http://hdl.handle.net/10019.1/97760 en_ZA Stellenbosch University vi, 96 pages : illustrations (some color), maps application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Neofabraea -- Pathogenesis Fungal gene expression Apples -- Postharvest diseases and injuries Pome fruits -- Diseases and pests Lenticels Fruit -- Diseases and pests -- Biological control -- South Africa -- Western Cape Pears -- Diseases and pests UCTD Rochefort, Jessica Epidemiology and etiology of Neofabraea species causing lenticel decay of pome fruit in the Western Cape of South Africa |
| title | Epidemiology and etiology of Neofabraea species causing lenticel decay of pome fruit in the Western Cape of South Africa |
| title_full | Epidemiology and etiology of Neofabraea species causing lenticel decay of pome fruit in the Western Cape of South Africa |
| title_fullStr | Epidemiology and etiology of Neofabraea species causing lenticel decay of pome fruit in the Western Cape of South Africa |
| title_full_unstemmed | Epidemiology and etiology of Neofabraea species causing lenticel decay of pome fruit in the Western Cape of South Africa |
| title_short | Epidemiology and etiology of Neofabraea species causing lenticel decay of pome fruit in the Western Cape of South Africa |
| title_sort | epidemiology and etiology of neofabraea species causing lenticel decay of pome fruit in the western cape of south africa |
| topic | Neofabraea -- Pathogenesis Fungal gene expression Apples -- Postharvest diseases and injuries Pome fruits -- Diseases and pests Lenticels Fruit -- Diseases and pests -- Biological control -- South Africa -- Western Cape Pears -- Diseases and pests UCTD |
| url | http://hdl.handle.net/10019.1/97760 |
| work_keys_str_mv | AT rochefortjessica epidemiologyandetiologyofneofabraeaspeciescausinglenticeldecayofpomefruitinthewesterncapeofsouthafrica |