Spatio-temporal dynamics on a plot scale of cocoa black pod rot caused by Phytophthora megakarya in Cameroon

Nkeng, Michel Ndoumbé; Mousseni, Ives Bruno Efombagn; Nomo, Lucien Bidzanga; Sache, Ivan; Cilas, Christian

doi:10.1007/s10658-016-1027-2

Cited by 13 publications

(13 citation statements)

References 35 publications

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“…In order to evaluate the degree of spatial autocorrelation between neighbouring plots, Moran's I test was used in ArcGIS Desktop ® 10.2 software (ESRI 2011) using the coordinates of each plot and its respective level of damage index (Al-Kindi et al 2017, Nkeng et al 2017. The collinearity among characteristics of a single seedling (type of tissue, height, diameter) and of the site (altitude, aspect, stand treatment) was first checked based on the Pearson correlation (α = 0.01) using R cran (R Core Teamhttp://www.r-project.org).…”

Section: Discussionmentioning

confidence: 99%

Evaluating the impact of Hymenoscyphus fraxineus in Trentino (Alps, Northern Italy): first investigations

Giongo¹,

Longa²,

Maso³

et al. 2017

iForest

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The spread of Hymenoscyphus fraxineus has been causing great concern regarding the survival of European ash (Fraxinus excelsior) throughout Europe since the 1990s. The disease was first recorded in Trentino (southern Alps, Italy) in 2012 and has spread throughout the mountain landscape, where ash trees are scattered in small and isolated stands in different valleys. The status of the disease was checked by monitoring the damage to natural regeneration and adult trees in 90 sites spread over the whole region. The survey confirmed the complete colonization by the pathogen of the whole investigated area, with high levels of damage to both young and adult ash trees. Regeneration (both seedlings and saplings) was observed to be affected by the fungus in 88 plots out of 90. Out of 4486 examined young European ashes, 2261 (50.4%) were affected and 789 (17.6%) were already dead. Ten of the 384 assayed flowering ashes (Fraxinus ornus) showed symptoms on branches and apical stems, similar to those observed for European ash. Isolation and molecular analysis proved the presence of the fungus on both symptomatic European and flowering ashes. The examined 386 adult trees showed different levels of damage, sometimes reaching more than 75% of the crown. Some individual trees (42) growing close to severely damaged trees appeared fully healthy, which suggests the possible existence of some resistant/tolerant individuals in the examined populations.

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Section: Discussionmentioning

confidence: 99%

Evaluating the impact of Hymenoscyphus fraxineus in Trentino (Alps, Northern Italy): first investigations

Giongo¹,

Longa²,

Maso³

et al. 2017

iForest

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show abstract

“…When cocoa is not well dried, buyers apply a 'refraction rate' to account for weight loss during further drying. In addition, pests and diseases contribute greatly to poor cocoa yields (van Vliet and Giller 2017) and are responsible for about 30%-40% of cocoa yield loss worldwide (Diby et al 2017;Ndoumbe-Nkeng et al 2017), which might explain why they are given a higher priority by farmers. Fungicide application and shade management are more important to farmers in the humid forest as a strategy to obtain high cocoa yields.…”

Section: Farmers' Perceptions Of Soil Fertility Were Consistent With mentioning

confidence: 99%

Farmers’ Perceptions as a Driver of Agricultural Practices: Understanding Soil Fertility Management Practices in Cocoa Agroforestry Systems in Cameroon

et al. 2020

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In Africa, cocoa yields are low, partly due to soil fertility constraints and poor management. While peoples’ knowledge, aspirations, and abilities are key factors explaining their behaviour, little is known about the rationales that underpin soil fertility management practices (SFMPs) of cocoa farmers. To address this gap, we conducted an exploratory survey in two contrasting regions in Cameroon where cocoa is an important crop: the humid forest and the forest-savannah transition zone. Some 30% of farmers in the transition zone as opposed to 13% in the humid forest expressed concerns about soil fertility. The most relevant soil fertility indicators for farmers were high cocoa yield, dark soil colour, ease of tillage, and floral composition. To enhance and maintain soil fertility, farmers used residues from weeding (100%), planting of trees (42%), mineral fertilisers (33%), compost (16%), and manure (13%). More farmers in the transition zone than the humid forest implemented SFMPs. Our findings suggest that soil fertility perceptions, access to inputs, local practices, and experience influence farmers’ use of SFMPs. The limited use of mineral fertilisers was explained by poor access whereas the use of organic fertilisers and tree planting were mostly constrained by lack of labour and knowledge. Farmers prioritised practices to increase yield and viewed SFMPs to be the least important management practices, although they believe high cocoa yield is an important indicator of soil fertility. To foster sustainable cocoa intensification, it is necessary to enhance farmers’ knowledge on SFMPs, increase access to inputs, and ensure returns on investment while considering farmers’ priorities and practices.

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“…Understanding the spatial distribution of FRD can help in the determination of inter-relationships between inoculum build-up and disease severity, the influence of abiotic factors on pathogen dynamics, and in risk assessment of disease in plants other than arecanut [34][35][36][37][38]. Different spatial disease distribution analysis methods are used to characterize the spatial positions of pathogens and locations of disease-affected gardens [39][40][41][42][43]. Spatial autocorrelation is generally used to determine the correlation between spatial data at different distance intervals in order to derive spatial dependence [42,44].…”

Section: Introductionmentioning

confidence: 99%

“…Different spatial disease distribution analysis methods are used to characterize the spatial positions of pathogens and locations of disease-affected gardens [39][40][41][42][43]. Spatial autocorrelation is generally used to determine the correlation between spatial data at different distance intervals in order to derive spatial dependence [42,44].…”

Section: Introductionmentioning

confidence: 99%

Assessment of the Spatial Distribution and Risk Associated with Fruit Rot Disease in Areca catechu L.

Patil

Sridhara

Shil

et al. 2021

JoF

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Phytophthora meadii (McRae) is a hemibiotrophic oomycete fungus that infects tender nuts, growing buds, and crown regions, resulting in fruit, bud, and crown rot diseases in arecanut (Areca catechu L.), respectively. Among them, fruit rot disease (FRD) causes serious economic losses that are borne by the growers, making it the greatest yield-limiting factor in arecanut crops. FRD has been known to occur in traditional growing areas since 1910, particularly in Malnad and coastal tracts of Karnataka. Systemic surveys were conducted on the disease several decades ago. The design of appropriate management approaches to curtail the impacts of the disease requires information on the spatial distribution of the risks posed by the disease. In this study, we used exploratory survey data to determine areas that are most at risk. Point pattern (spatial autocorrelation and Ripley’s K function) analyses confirmed the existence of moderate clustering across sampling points and optimized hotspots of FRD were determined. Geospatial techniques such as inverse distance weighting (IDW), ordinary kriging (OK), and indicator kriging (IK) were performed to predict the percent severity rates at unsampled sites. IDW and OK generated identical maps, whereby the FRD severity rates were higher in areas adjacent to the Western Ghats and the seashore. Additionally, IK was used to identify both disease-prone and disease-free areas in Karnataka. After fitting the semivariograms with different models, the exponential model showed the best fit with the semivariogram. Using this model information, OK and IK maps were generated. The identified FRD risk areas in our study, which showed higher disease probability rates (>20%) exceeding the threshold level, need to be monitored with the utmost care to contain and reduce the further spread of the disease in Karnataka.

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Spatio-temporal dynamics on a plot scale of cocoa black pod rot caused by Phytophthora megakarya in Cameroon

Cited by 13 publications

References 35 publications

Evaluating the impact of Hymenoscyphus fraxineus in Trentino (Alps, Northern Italy): first investigations

Evaluating the impact of Hymenoscyphus fraxineus in Trentino (Alps, Northern Italy): first investigations

Farmers’ Perceptions as a Driver of Agricultural Practices: Understanding Soil Fertility Management Practices in Cocoa Agroforestry Systems in Cameroon

Assessment of the Spatial Distribution and Risk Associated with Fruit Rot Disease in Areca catechu L.

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