Management of cocoa: Constraints during acquisition and application of pesticides in the humid forest zones of southern Cameroon

Sonwa, D.J.; Coulibaly, Ousmane; Weise, Stéphan; Adesina, Akinwumi A.; Janssens, Marc J. J.

doi:10.1016/j.cropro.2008.02.004

Cited by 37 publications

(30 citation statements)

References 7 publications

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“…It is also similar to that of the systemic fungicides commonly employed by cacao producers in Cameroon (3 weeks). However, it is somewhat longer than that of contact fungicides such as Kocide 2000, which in practice demand a fortnightly application (Sonwa et al, 2008). Persistence probably results from the ability of Trichoderma species -when appropriately formulated -to colonize the cortex of the cacao pods, even when exposed to direct sunlight (Krauss et al, 2006;Ten Hoopen et al, 2003).…”

Section: Discussionmentioning

confidence: 99%

A new oil-based formulation of Trichoderma asperellum for the biological control of cacao black pod disease caused by Phytophthora megakarya

et al. 2014

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HIGHLIGHTS• New oil-based dispersion with a half-life of T. asperellum conidia of 22.5 weeks.• Complete inhibition of P. megakarya on sprayed detached pods.• Enhanced rate and duration of protection on sprayed cacao pods in the field.• 50% of pods protected 3.2 weeks after spraying in the field.• Formulation suitable for the spraying equipment of small-scale cacao producers. GRAPHICAL ABSTRACTFormulated conidia of Trichoderma provide similar or even better protection of cacao pods against black pod disease than a conventional fungicide. ABSTRACTIn African cacao-producing countries, control of cacao black pod disease caused by Phytophthora megakarya is a priority. Introducing biological control agents as part of a P. megakarya control strategy is highly desirable, especially in a perspective of pesticide reduction. Trichoderma species are among the most used biological control agents. In Cameroon, Trichoderma asperellum formulated in wettable powder has produced positive effects against this disease. However, with this type of formulation, shelf-life and persistence of conidia on pods are limited. Our study therefore sought to develop a new T. asperellum formulation that would be more effective and better suited to the conditions of field application by small-scale producers in Cameroon. We selected a soybean oil-based oil dispersion, in which the half-life of the conidia reached 22.5 weeks, versus 5 weeks in Published in : Biological Control (2014), vol. 77, pp. 15-22 Status : Postprint (Author's version) aqueous suspension. Tested on detached pods, the formulation completely inhibited the development of the disease. When sprayed in the field on cacao clones highly sensitive to P. megakarya, the formulation resulted in 90% protection of treated pods after 1 week, and 50% after 3.2 weeks. The formulations exercised a measurable effect for up to 7 weeks, versus 2 weeks in the case of an aqueous conidial suspension and 5 weeks for that of a conventional fungicide (Kocide). Trichoderma asperellum formulated in oil dispersion has therefore great potential for the control of cacao black pod disease with less recourse to synthetic fungicides.

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Section: Discussionmentioning

confidence: 99%

A new oil-based formulation of Trichoderma asperellum for the biological control of cacao black pod disease caused by Phytophthora megakarya

et al. 2014

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“…In order to prevent these losses due to P. megakarya infection, different strategies have been developed. Chemical control using metalaxyl and copperbased fungicides has been reported to be the most effective strategy to reduce the impact of BPD in nurseries and in farms (Ndoumbe-Nkeng et al, 2004;Sonwa et al, 2008). However, application of fungicides can have drastic effects on the consumer and the environment (Naseby et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Effects of chitosan and snail shell powder on cocoa (Theobroma cacao L.) growth and resistance against black pod disease caused by Phytophthora megakarya

Tayo¹,

Ewane²,

Effa³

et al. 2017

Afr. J. Plant Sci.

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Chitosan and chitin sources have emerged as promising groups of biological substances that can induce plant growth and resistance to diseases. This study is aimed at investigating the potential effect of chitosan and snail shell to promote cocoa growth and induce resistance against Phytophthora megakarya. The results showed that treatment of cocoa seeds with chitosan at 1.5 to 2.0% and snail shell at 2.0% increases the percentage of germination and also reduces the time of germination. 12 weeks after planting, a series of morphological changes was observed on the plants treated with chitosan and snail shell. Plant height (34 to 39.5 cm), leaf number (11 to 13 leaves/plant), leaf area (88 to 130 cm 2 ) and fresh weight of roots and shoots (25 to 44 g/plant) increased significantly in the chitosan and snail shell treated soils. Pods inoculated with chitosan and/or snail shell treated soil suspensions presented very slight necrotic lesions. This could be linked to a decrease in the P. megakarya load of the soil suspension. Leaf inoculation showed variation among the treatments with the lowest index (highest level of resistance) recorded in plants treated either with chitosan or snail shell. The treatment of plants with chitosan and snail shell powder before and after inoculation showed higher level of phenolic compounds than in the control plants. Furthermore, the inoculation induced a significant accumulation of proteins in the cocoa plants treated with chitosan and snail shell. The level of proteins accumulation after inoculation was higher in plants treated with snail shell than those treated with chitosan. In conclusion, the effect of snail shell on cocoa growth and resistance showed that it is possible for snail shell powder to be a biofungicide and biofertilizer used in the control of cacao Black Pod Disease in nurseries.

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“…Classically, pesticides are used to reduce the incidence of black pod disease (BPD). However, these chemicals appeared to be environmentally unfriendly, expensive, and inefficient (Sonwa et al, 2008). Hence, breeding for tolerance to BPD appeared to be the way out for sustainable cocoa culture (Iwaro et al, 2005;Ramalho et al, 2012;Bohinc and Trdan, 2012).…”

Section: Introductionmentioning

confidence: 99%

“…In Cameroon, cocoa is one of the most economically important crops grown by small farmers for their livelihoods (Sonwa et al, 2008;ICCO, 2013ICCO, , 2015. However, there is approximately 50 -80% of cocoa production harvest losses because of an oomycete, Phytophthora megakarya, the pathogen of black pod disease in Cameroon (Djocgoue et al, 2010;Mfegue, 2012).…”

Section: Introductionmentioning

confidence: 99%

Assessment of three cocoa hybrid families susceptibility and cysteine involvement in defense process against Phytophthora megakarya

Minyaka¹,

Claude²,

Cyrille³

et al. 2017

Afr. J. Biotechnol.

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Black pod disease (BPD) is the major cocoa pathology constraint caused by an Oomycete, Phytophthora megakarya prevailing in African cocoa producing countries. The development of T. cacao planting material tolerant to BPD lies on cross-pollination of adequate parental genotypes which generate offspring with desirable traits. We assessed the susceptibility to BPD of offspring derived from three manual crosses (SNK13xUPA143, T79/501xUPA143 and UPA143xSNK64) using leaf discs test (LDT) which evaluates disease scores of hybrid genotypes. Cysteine involvement in T. cacao defence process against BPD has been studied for the potential use of this sulphur amino acid profile to identify tolerant cocoa hybrid genotypes. LDT displayed variable disease scores patterns. Within a given family, LDT revealed heterogeneity in disease scores. This heterogeneity may have been derived from polygenic character of T. cacao susceptibility to BPD. In SNK13xUPA143 family, 26.13% exhibited disease scores lower than two (tolerant hybrid genotypes). T79/501xUPA143 and UPA143xSNK64 generated 21.18 and 26.46% of tolerant hybrid genotypes respectively. This variability between families may have resulted from deferential susceptibility of parental clones; UPA143 being more susceptible than T79/501 followed by SNK13. SNK64 was the less susceptible to BPD. The percentages of tolerant hybrid genotypes in this study appeared to be consistent hence, SNK13xUPA143, T79/501xUPA143 and UPA143xSNK64 could be used to produce hybrids genotypes tolerant to BPD. Cysteine analysis was performed in none detached healthy and wounded-infected leaves of hybrid genotypes with variable disease scores. It appeared that cysteine was mobilized during the infection. Two main patterns were observed: in tolerant hybrid genotypes (disease score lower than 2), infection was associated to a significant reduction of cysteine content in young leaves while in susceptible hybrid genotypes, infection was associated to an increase (accumulation) of cysteine in young leaves. Cysteine could be involved in the synthesis of effective defence molecules against P. megakarya in tolerant hybrid genotypes. This set of finding may indicate that cysteine profile could be used to discriminate tolerant from susceptible hybrid genotypes of T. cacao to P. megakarya.

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Management of cocoa: Constraints during acquisition and application of pesticides in the humid forest zones of southern Cameroon

Cited by 37 publications

References 7 publications

A new oil-based formulation of Trichoderma asperellum for the biological control of cacao black pod disease caused by Phytophthora megakarya

A new oil-based formulation of Trichoderma asperellum for the biological control of cacao black pod disease caused by Phytophthora megakarya

Effects of chitosan and snail shell powder on cocoa (Theobroma cacao L.) growth and resistance against black pod disease caused by Phytophthora megakarya

Assessment of three cocoa hybrid families susceptibility and cysteine involvement in defense process against Phytophthora megakarya

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