The spread of phytophthora megakarya on cocoa in Ghana

No Abstract. Journal of the Ghana Association Vol. 2 (3) 1999: pp.110-11

Phytophthora megakarya: A potential threat to the cocoa industry in Ghana

A severe black pod disease of cocoa in Ghana caused by Phytophthora megakarya was first reported in 1985, even though there is evidence that the fungus might have existed earlier. Until then, only Phytophthora palmivora which causes a less severe black pod disease was known in Ghana. P. megakarya has changed the status of black pod disease in Ghana, causing serious crop losses and great concern among farmers. The distribution, disease characteristics and spread of P. megakarya, the black pod disease incidence and effects on yield of cocoa in Ghana, are reviewed. Records of cocoa sales and data from on-farm farmer-managed control trials have been presented to illustrate cocoa-yield patterns in P. palmivora and P. megakarya-affected districts. Problems associated with the control of black pod disease caused by P. megakarya, and the measures developed for its management are also discussed. Because black pod disease caused by P. megakarya poses a serious threat to cocoa production in Ghana, efforts should be made by all stakeholders to ensure its effective management. Phytophthora megakarya: Une menace potentielle à l' industrie de cacao au Ghana Résumé Une maladie grave de cosse noire du cacao au Ghana causée par Phytophthora megakarya était signalée pour la première fois en 1985, malgré le fait qu'il ait une évidence que le fongus aurait pu être présent avant cette date. Jusque-là, c'est seulement Phytophthora palmivora, qui est la cause d'une maladie moins grave de cosse noire, était connue au Ghana. P. megakarya a changé la situation de la maladie de cosse noire au Ghana, causant des pertes sévères des cultures et de grande inquiétude pour les cultivateurs. La distribution, les caractéristiques de maladie et propagation de P. megakarya, la situation de la maladie de cosse noire et son effet sur le rendement de cacao au Ghana sont passés en revue. Les rapports des ventes de cacao, et les données des essais de contrôle exploité par le cultivateur sur le champ ont été présenté pour illustrer les orientations de rendement de cacao dans les districts affectés par P. palmivora et P. megakarya. Les problèmes liés au contrôle de la maladie de cosse noire causés par P. megakarya et les démarches développées pour son contrôle sont également discutés. Puisque la maladie de cosse noire causée par P. megakarya pose une menace serieuse à la production de cacao au Ghana, des efforts doivent être fait par toutes les dépositaires d'enjeux pour assurer son contrôle efficace. Ghana Jnl agric. Sci. Vol.33(2) 2000: 237-24

Vegetative propagation of kola (Cola nitida Vent. Schott and Endl.) by stem cuttings

The effects of some technical, environmental and physiological factors on the rooting of kola stem cuttings were investigated at the Cocoa Research Institute of Ghana from 1997 to 2002. These factors included hormonal, fungicidal and wounding treatments, rooting media, leaf area, and effects of type of wood. Within the range of concentration tested, indole-butyric acid (IBA) rooting hormone did not have any significant effect on rooting success. All the candidate fungicides tested were effective in reducing rotting of cuttings. However, the copper-based fungicides caused a slight reduction in rooting. No significant differences were recorded for effect of rooting media. Wounding treatment improved rooting in hardwood cuttings. Rooting was significantly better (P ≤ 0.05) in semi-hard- wood cuttings than in hardwood cuttings. Clipping of leaves to half the normal size had virtually the same results as leaving all leaves intact. Further areas to improve success in propagating kola by stem cuttings are discussed. Ghana Journal of Agricultural Science Vol. 38, 2005: 43-5

Biological control of cacao diseases

This chapter discusses the advances in biological control of cacao diseases over the last 15 years. Most attention has been focused on biological control of frosty pod rot (Moniliophthora roreri), witches' broom (Moniliophthora perniciosa) and black pod disease (Phytophthora spp.). Research on biocontrol of other diseases in the cacao phyllosphere or rhizosphere is scarce or in its infancy. There is, however, a steady increase in information regarding the factors influencing and the mechanisms underlying biological control of cacao diseases as well as practical aspects such as inoculum production, formulation and application. There has been a clear shift away from inundative approaches using epiphytic BCAs towards more classical biocontrol approaches using bacterial and fungal endophytes as well as vesicular arbuscular mycorrhiza. These have the advantage that they can permanently establish themselves in the cacao tree. Moreover, besides direct competition for space and nutrients, antibiosis and mycoparasitism, through induced resistance and growth promotion, endophytes have a larger arsenal of mechanisms through which they can help protect their host. Endophytic BCAs could thus provide more effective and sustainable disease control. Recent advances in our understanding of the mechanisms through which endophytic biocontrol agents can reduce pest and disease impact provide possibilities for innovative disease control strategies, including combination therapies together with natural or chemical products. Continued work on production, formulation and application is also necessary in order for biocontrol to become economically interesting. However, biological control will not become a stand-alone solution for disease control but should become part of integrated pest management strategies, with cultural management as a central and reinforcing pillar. (Résumé d'auteur