Articles
Etiology and management of black rot on ‘Forelle’ pears in the Western Cape
Article number
1403_26
Pages
207 – 210
Language
English
Abstract
Black rot on ‘Forelle’ pears in the Western Cape has shown an increase in reports from producers and packhouses.
The causal organisms of black rot have been reported as Diplodia seriata and Botryosphaeria dothidea and these reports were made in 1984 using only morphological identification methods and not molecular tools.
To determine the disease incidence, 500 fruit from 11 orchards across the Western Cape were harvested including the four main production regions (Elgin, Koue Bokkeveld, Warm Bokkeveld, and Villiersdorp). Harvested fruit was stored in cold storage at -0.5°C under regular atmosphere conditions for three months.
Black rot was confirmed all sampled regions with a mean 1.7% incidence black rot and a maximum incidence of 9.2%. Isolations were made from symptomatic pears.
Fungal cultures were hyphal-tipped and the species identity was determined using species-specific PCR. The main causal organism for black rot was determined to be D. seriata and isolates were collected in regions previously thought to be free of this pathogen.
Fungicide drench trials were performed with fludioxonil and pyrimethanil.
Results showed that fludioxonil drench was effective in controlling black rot at recommended dosages.
Pyrimethanil drench application did not effectively control black rot even at the two-time recommended dosages.
This study aided in the increase in knowledge of postharvest disease incidences in the Western Cape ‘Forelle’ pear production.
Results from this study confirm that D. seriata is the main causal organism for black rot on ‘Forelle’ pears in the Western Cape and that fludioxonil effectively controlled black rot of pears.
The causal organisms of black rot have been reported as Diplodia seriata and Botryosphaeria dothidea and these reports were made in 1984 using only morphological identification methods and not molecular tools.
To determine the disease incidence, 500 fruit from 11 orchards across the Western Cape were harvested including the four main production regions (Elgin, Koue Bokkeveld, Warm Bokkeveld, and Villiersdorp). Harvested fruit was stored in cold storage at -0.5°C under regular atmosphere conditions for three months.
Black rot was confirmed all sampled regions with a mean 1.7% incidence black rot and a maximum incidence of 9.2%. Isolations were made from symptomatic pears.
Fungal cultures were hyphal-tipped and the species identity was determined using species-specific PCR. The main causal organism for black rot was determined to be D. seriata and isolates were collected in regions previously thought to be free of this pathogen.
Fungicide drench trials were performed with fludioxonil and pyrimethanil.
Results showed that fludioxonil drench was effective in controlling black rot at recommended dosages.
Pyrimethanil drench application did not effectively control black rot even at the two-time recommended dosages.
This study aided in the increase in knowledge of postharvest disease incidences in the Western Cape ‘Forelle’ pear production.
Results from this study confirm that D. seriata is the main causal organism for black rot on ‘Forelle’ pears in the Western Cape and that fludioxonil effectively controlled black rot of pears.
Publication
Authors
M. Richard, L. Mostert, C.L. Lennox, J.C. Meitz-Hopkins
Keywords
Botryosphaeriaceae, fludioxonil, postharvest decay
Online Articles (42)