Disease assessment and yield loss

Cooke, B. M.

doi:10.1007/1-4020-4581-6_2

Cited by 101 publications

(58 citation statements)

References 76 publications

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“…Symptomatic stems of H. polyrhizus were randomly sampled from each plantation for further analysis. Disease incidence (DI) was calculated in each dragon fruit plantation according to Cooke's () equation. Disease severity (DS) was determined based on alternative rating scale proposed by Bowen () with the following scales: 0 = no symptom, 1 = 0–20% of severity level on infected plants, 2 = 20–40%, 3 = 40–60%, 4 = 60–80% and 5 = 80–100% and then calculated by an equation described by Kranz ().…”

Section: Methodsmentioning

confidence: 99%

Identification and Molecular Characterizations of Neoscytalidium dimidiatum Causing Stem Canker of Red‐fleshed Dragon Fruit (Hylocereus polyrhizus) in Malaysia

Mohd

Salleh

Zakaria

2013

Journal of Phytopathology

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During the year 2008 to 2009, a new disease of stem canker was noticed in most red‐fleshed dragon fruit (Hylocereus polyrhizus) plantations in Malaysia. The symptoms observed were small circular sunken orange spot, black pycnidia and rotted stem. This study was conducted to determine the occurrence of the stem canker on H. polyrhizus in Malaysia, subsequently to isolate, identify and characterize the fungal pathogen based on morphology and molecular characteristics and pathogenicity test. From the surveyed 20 plantations in Malaysia, stem canker was detected in all the plantations. A total of 40 isolates of Scytalidium‐like fungus were isolated and identified as Neoscytalidium dimidiatum based on morphological characteristics and ITS region sequences, which showed 99% similarity to N. dimidiatum (FJ648577). From the phylogenetic analysis using maximum‐likelihood tree, isolates of N. dimidiatum from stem canker of H. polyrhizus were grouped together and did not show any sequence variation. From pathogenicity test, all 40 isolates of N. dimidiatum were pathogenic causing stem canker on H. polyrhizus. To our knowledge, this is the first report of stem canker of H. polyrhizus caused by N. dimidiatum in Malaysia.

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Section: Methodsmentioning

confidence: 99%

Identification and Molecular Characterizations of Neoscytalidium dimidiatum Causing Stem Canker of Red‐fleshed Dragon Fruit (Hylocereus polyrhizus) in Malaysia

Mohd

Salleh

Zakaria

2013

Journal of Phytopathology

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“…In addition, disease severity was assessed using a standard disease scale of 0 to 5 (Winstead and Kelman, 1952) where 0: no symptom; 1: only the inoculated leaf wilted; 2: 2 to 3 leaves wilted; 3: four leaves wilted; 4: all leaves wilted and 5: plant dead). The severity grades were converted into percentage severity index for analysis (Cooke, 2006).…”

Section: Disease Assessmentmentioning

confidence: 99%

Natural occurrence and pathogenicity of Xanthomonas bacteria on selected plants

Chala¹,

Kebede²,

Blomme³

2016

Afr. J. Biotechnol.

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The bacterial genus Xanthomonas consists of several species of economic importance, among which Xanthomonas campestris pv.musacearum (Xcm), the cause of enset and banana wilt is the most important in tropical Africa. However, the natural occurrence and host range of this species is yet to be clarified. The objectives of this study were to verify the presence of Xanthomonas bacteria on plants growing in and around enset gardens in South and Southwest Ethiopia, and to elucidate the pathogenicity of Xcm strains to cultivated and wild plants. Several economical and ornamental plants were assessed for wilting in South and Southwest Ethiopia. Wilting was visible on Canna spp. with 9.8% incidence and 30% prevalence, while reddish streak symptoms (typical of Xanthomonas bacteria) were observed on the leaves of sugarcane, sorghum and wild sorghum with disease incidence ranging from 20 to 80%, and prevalence varying from 30 to 100%. The pathogenicity of three Xcm isolates to five plant species was tested in a factorial experiment arranged in CRD with five replications. All the tested Xcm isolates were found to be pathogenic to banana, cultivated and wild enset, Canna indica, Canna orchoides, maize, sorghum and finger millet. The analysis of variance for incubation period and disease incidence revealed significant differences (p<0.05) among test plants and isolates. Results suggest marked variations among test plants' ability to resist the bacterium. Variations were also evident in the aggressiveness of the bacterial isolates. On the other hand, enset and banana did not show any symptom after being inoculated with four Xanthomonas isolates from other crops.

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“…The average yield loss of 30.6% from the three BPE periods was similar to the report from Taiwan (Hartman and Wang ), although the latter was obtained from artificial inoculation. James () and Cooke () stated many of the confounding factors that weakened the statistical relationship between disease levels and yield. These factors may have contributed for a similar poor correlation of marketable yield with disease severity in this study.…”

Section: Discussionmentioning

confidence: 99%

“…The average yield loss of 30.6% from the three BPE periods was similar to the report from Taiwan (Hartman and Wang 1992), although the latter was obtained from artificial inoculation. James (1983) and Cooke (2006) stated many of the confounding factors that weakened the statistical relationship between February 2006 January 2006 0 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 0 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 0 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 0 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 0 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 0 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 Fig. 7 A 24-h course of mean hourly temperature (°C) and relative humidity (%) in the 50-mesh BioNet TM greenhouses during the months of August to December in 2005 and January to February in 2006.…”

Section: Discussionmentioning

confidence: 99%

Seasonal Dynamics of Black Leaf Mould (Pseudocercospora fuligena) on Greenhouse‐Grown Fresh Market Tomatoes

Mersha

Zhang

Hau

2013

Journal of Phytopathology

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Black leaf mould (BLM), caused by Pseudocercospora fuligena, is a major fungal foliar disease of greenhouse-grown tomatoes in the humid tropics. Quantifying the disease and yield loss from seasonal plantings will help mitigate the heavy reliance on frequent sprays of curative fungicides. In this study, severity of BLM was investigated in sequential plantings of tomatoes in two 50-mesh BioNet greenhouses in central Thailand from June 2005 to January 2007. Each planting consisted of a block of six plants that received two applications of mancozeb and another block of six plants with no fungicide application at all. Two BLM peak epidemic periods were identified, that is, from plantings that were started in August-September and in January. On average, a yield loss of 30.6% was recorded from the two peak epidemic periods based on comparison of fungicide-sprayed and non-sprayed plants. Two sprays of mancozeb resulted in 71.6% reduction in disease severity during these peak epidemic periods. Mean disease severity (DS*) was highly correlated with a favourability index of relative humidity (RH), which was quantified on a scale of 0 (<85%, nonfavourable) to 1 (≥85%, extremely favourable). A three-parameter logistic function explained the data well (R 2 = 0.81, P < 0.0001). Marketable yield (MY) was positively correlated with maximum plant height (PH max ) but negatively correlated with DS*. In addition, MY was higher from plantings during October to December. It was predicted well (R 2 = 0.60; P < 0.0001) using the model MY = (a + b 9 PH max ) 9 (1-c 9 DS*), which combined both PH max and DS*. Using this model, a reduction of 1.05% in marketable yield was predicted for each 1% increase in mean disease severity. The outcomes of this study implicated the need for management of RH and critical relevance of protecting tomato plants against BLM when they are grown during the peak epidemic periods.

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Disease assessment and yield loss

Cited by 101 publications

References 76 publications

Identification and Molecular Characterizations of Neoscytalidium dimidiatum Causing Stem Canker of Red‐fleshed Dragon Fruit (Hylocereus polyrhizus) in Malaysia

Identification and Molecular Characterizations of Neoscytalidium dimidiatum Causing Stem Canker of Red‐fleshed Dragon Fruit (Hylocereus polyrhizus) in Malaysia

Natural occurrence and pathogenicity of Xanthomonas bacteria on selected plants

Seasonal Dynamics of Black Leaf Mould (Pseudocercospora fuligena) on Greenhouse‐Grown Fresh Market Tomatoes

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