https://search.dev.ndltd.org/etd/massey/oai:mro.massey.ac.nz:10179/3768
type: CreativeWork
name: Epidemiology and management of Sclerotinia sclerotiorum (Lib.) de Bary in kiwifruit (Actinidia deliciosa (A. Chev.)) : this thesis is presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science at Massey University, Palmerston North, New Zealand
description: Kiwifruit (Actinidia deliciosa (A. Chev.) C. F. Liang et A. R. Ferguson, var. deliciosa cv. „Hayward?), a valuable fruit grown in New Zealand orchards for export, is susceptible to the necrotrophic and cosmopolitan fungus Sclerotinia sclerotiorum (Lib.) de Bary. Sclerotinia disease causes direct crop loss in the form of diseased fruitlets, scarring of fruit and field rot of fruit. Costs to the industry amounting to an estimated $5 million pa. are incurred through crop loss on vines or during grading and through the purchase and application of fungicide. This study showed that 19% (range 0–53%) of 3–4 day-old kiwifruit petals were colonised by S. sclerotiorum ascospores arising from apothecia that were present within most orchards. Adhering floral tissues (AFT) were present on 38% of fruit 7–8 weeks after anthesis and 11% (range 0–43%) of these were colonised by S. sclerotiorum. The incidence of fruit with scarring was significantly higher on fruit with AFT than fruit without AFT. Removal of AFT 10–14 days after anthesis resulted in a 66% reduction in diseased fruitlets and a 85% reduction in fruit with scarring. Adhering floral tissues on fruit were therefore determined to be a major source of secondary spread. An in vitro assay was developed in which freshly detached kiwifruit petals were inoculated with dry S. sclerotiorum ascospores in a settling chamber and incubated for 72 h. The number of discrete colonies which formed on selective agar medium, when macerated petal tissue was spread on the agar, effectively quantified petal colonisation. Colonisation of petals significantly increased with increasing flower age. Colonisation of petals incubated under static conditions within saturated salt chambers was highest between 18–27oC and 90–100% relative humidity. Colonisation of petals in dynamically controlled environment chambers was inhibited by incubation in diurnally fluctuating temperature and relative humidity conditions typical of days with <5 mm rainfall duri…
abstract: Kiwifruit (Actinidia deliciosa (A. Chev.) C. F. Liang et A. R. Ferguson, var. deliciosa cv. „Hayward?), a valuable fruit grown in New Zealand orchards for export, is susceptible to the necrotrophic and cosmopolitan fungus Sclerotinia sclerotiorum (Lib.) de Bary. Sclerotinia disease causes direct crop loss in the form of diseased fruitlets, scarring of fruit and field rot of fruit. Costs to the industry amounting to an estimated $5 million pa. are incurred through crop loss on vines or during grading and through the purchase and application of fungicide. This study showed that 19% (range 0–53%) of 3–4 day-old kiwifruit petals were colonised by S. sclerotiorum ascospores arising from apothecia that were present within most orchards. Adhering floral tissues (AFT) were present on 38% of fruit 7–8 weeks after anthesis and 11% (range 0–43%) of these were colonised by S. sclerotiorum. The incidence of fruit with scarring was significantly higher on fruit with AFT than fruit without AFT. Removal of AFT 10–14 days after anthesis resulted in a 66% reduction in diseased fruitlets and a 85% reduction in fruit with scarring. Adhering floral tissues on fruit were therefore determined to be a major source of secondary spread. An in vitro assay was developed in which freshly detached kiwifruit petals were inoculated with dry S. sclerotiorum ascospores in a settling chamber and incubated for 72 h. The number of discrete colonies which formed on selective agar medium, when macerated petal tissue was spread on the agar, effectively quantified petal colonisation. Colonisation of petals significantly increased with increasing flower age. Colonisation of petals incubated under static conditions within saturated salt chambers was highest between 18–27oC and 90–100% relative humidity. Colonisation of petals in dynamically controlled environment chambers was inhibited by incubation in diurnally fluctuating temperature and relative humidity conditions typical of days with <5 mm rainfall duri…
author: Hoyte, Stephen
keywords: Kiwifruit, Actinidia deliciosa, Sclerotinia sclerotiorum, Kiwifruit diseases
date published: 2001
date modified: 2026-07-27T20:17:07Z
provider: Massey University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Massey University