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The cocoa swollen shoot virus disease persists in Ghana in spite of the implementation of an eradication campaign against the disease by the government since 1948. Two major factors are identified as limiting the success of the eradication campaign. First, the extension problem, namely, the low level of growers' knowledge (know-why) concerning the disease, including knowledge of the causal agent (3.8%), the vectors (2.3%), and the recommended preventive measures (8% to 67%). Second, the implementation problem, namely, the failure of growers and government-employed labourers to follow the recommended policy of cutting-out and replanting cocoa farms. Thus, about half (51%) of the affected farms were not correctly treated, despite the specialized labour provided and paid for by the government to implement treatment. In addition, about 73% of the growers who treated their affected farms without government support did so incorrectly. Other factors include the direct treatment cost (US $513.00 ha−1) to be borne by growers, as well as land tenure arrangements, and the waiting time of at least three years before the first harvest after replanting. A more researcher-grower collaborative approach in managing the disease could enhance growers' knowledge and the adoption of recommended practices to limit the spread of the disease. In addition, policy decisions on a nationwide disease management strategy that require growers' collective efforts should consider growers' socio-economic conditions like land tenure arrangements and disease treatment cost (direct and indirect) incurred by growers. [ABSTRACT FROM AUTHOR]

Soil organic carbon and main nutrient stocks play key roles in maintaining soil fertility and yields of agricultural crops including cocoa (Theobroma cacao). The amount of nutrients removed from the soil by the cocoa trees could be influenced by its physiological growth stage. A study was carried out to examine the changes in some soil physical and chemical properties with main nutrients availabilities under cocoa plantations at the Cocoa Research Institute in the Eastern Region of Ghana. Cocoa plantations of different ages (5, 10, 14, 18 and 23 years) were chosen based on similar land history. Soils at the study sites are classified as Xanthic Ferralsol (WRB series). On each plantation, one acre (0.4ha) plot was demarcated and divided into three blocks for soil sampling. Five core samples were taken at 0–15 cm depth per block, bulked together and subsample taken to the laboratory for analyses. Particle size analyses showed that all soils were of sandy loam texture. All soils were acidic with pH below 5.5, relatively low exchangeable K and Ca. Bulk density values varied with ages at highest in 18 years. Soils under 23 years old plantations had relatively lower bulk density than those of the other ages. Total nitrogen content under the 5, 10, and 18 years of cocoa plantations was below the critical values considered adequate for good cocoa growth. Soil carbon stock and available phosphorus content of the soil generally tend to increase with age of the cocoa plantations. These differential variations in the soil nutrients, namely, total N, available P, exchangeable K, Ca, and Mg among five different cocoa plantation ages suggest that total nitrogen, available P, and exchangeable Mg were higher than the critical levels for good cocoa growth under 23 years of cocoa plantations only, but exchangeable K and Ca were lower the critical levels for all ages of cocoa plantations. [ABSTRACT FROM AUTHOR]

Cocoa swollen shoot virus disease (CSSVD) is a major disease of cacao (Theobroma cacao L.) in Ghana and other West African countries that grow the crop. Attempts to develop resistant varieties since the discovery of the disease in 1936 have yielded little success. Recently, planting materials that are tolerant to the disease have been recommended for planting in areas with high CSSVD prevalence. However, the effect of CSSVD on yield component traits of most cacao clones including the tolerant varieties has not been well studied. To investigate the impact of CSSVD on these traits, reduction in bean weight (BW), number of beans per pod (NoBP) and dry bean yield (DBY) between symptomless and symptomatic trees, and disease incidence (DI) among 210 different cacao clones were evaluated. The clones were transplanted in June 2010 following a randomised complete block design with four replications consisting of three trees per clone per block. Response of the clones to CSSVD incidence had 180 of the genotypes having < 50% symptoms. Clones of Contanama, Iquitos, Marañon, Nanay and unknown derived from Upper Amazon parentage had less DI at the end of the study. The CSSVD effect (symptomless vs. symptomatic) was significant (p < 0.05) for DBY and NoBP, and the symptomless trees surpassed on average their symptomatic trees by 21.17% for DBY. Some of the best-performing clones identified under natural CSSVD infection were; COCA 3348/52 and GU 219/V among the underrepresented clones, B 36, ICS 40, NA 33 x IMC 67, T30/628, T60/887, T63/971, T 81/1879 and T 82/503 among those that combine high DBY with low yield reduction, and NA 124, T17/358, T35/78, T57/305, T63/971 x SCA 6, T65/239, T76/1835 and T82/2294 among those that combine high DBY with no disease incidence. Their inclusion in breeding programs that seek to develop resistant CSSVD varieties or deployment as planting materials in endemic areas to improve yield production in Ghana is recommended on the basis of the present observations. [ABSTRACT FROM AUTHOR]

Abstract: The present study examines the gains in resistance to cocoa swollen shoot virus (CSSV) infection from investments in breeding over the past seven decades. The general susceptibility to CSSV infection of the West African Amelonado that dominated plantings prior to the start of formal research in 1938 necessitated the introduction of germplasm of Upper Amazon origin to better contain the disease spread. Included in this study are findings of two recent experiments. In the first, the genetic basis for resistance in the clone mvT85, developed from gamma radiation of clone T85/799 and putatively resistant to CSSV disease was investigated. In the second experiment, the comparative levels of resistance in sets of old, current and new cocoa varieties were tested following inoculations with the severe CSSV strain 1A. Absence of nucleotide differences at 29 single nucleotide polymorphism (SNP) loci between mvT85 and T85/799, and lack of segregation for resistance in the full-sib and backcross populations derived from mvT85 indicated that mvT85 did not carry novel genes for improving cocoa for CSSV disease resistance. Moreover, there were no differences in resistance to CSSV disease between mvT85 and T85/799. These observations conflict with the previous report that mvT85 is immune to CSSV disease, and distinct from T85/799. Between variety groups, disease severity scores based on three successive leaf flushes after inoculation were not effective in discriminating among them. Disease severity assessed eight months after inoculation was the most important criterion for separating varieties for resistance to CSSV disease. As expected, the older varieties were the most sensitive to infection. No differences were found between current varieties derived exclusively from Upper Amazon clones and new varieties. Contrary to the generally held opinion of a higher level of resistance in existing inter Upper Amazon cultivars, varieties derived from crosses using Catongo, RB 49 and C-SUL 7 (all of Lower Amazon origin) as males with specific Upper Amazon varieties were among the most resistant. A re-appraisal of variety recommendations for areas of mass infection and for less affected areas is advocated. [Copyright &y& Elsevier]

The cocoa swollen shoot virus disease is a major factor limiting cocoa (Theobroma cacao L.) productivity for West African farmers. The only treatment against this disease is to cut infected trees and replant with disease-free planting material. Research has recommended the prevention measures: (i) cordon sanitaire (leaving 10-m-wide cocoa-free zone around cocoa), (ii) barrier cropping, (iii) using partly tolerant hybrids, and (iv) removing specific alternative host tree species. Here, we evaluate the current adoption of these measures and identify their adoption constraints. We conducted a quantitative survey with 396 farmers in the Eastern and Western Regions of Ghana, held six focus group discussions and hosted a multi-stakeholder validation workshop with 31 key actors in the cocoa value chain. Our results indicate that the adoption of prevention measure against the disease remains limited. Farmers with a more extensive social network (number of family members/close friends who already adopted a particular measure), a larger farm size, more secure land tenure rights, and more knowledge about the measures were more likely to adopt them, especially barrier cropping, hybrid seedlings, and removing alternative host trees. Lack of knowledge about the measures was the single biggest barrier for their adoption, with 51% of the participating farmers not even being aware of any prevention measures. Here, we show for the first time that the social network is the main information source for farmers, which agrees with the finding that the flow of information between farmers and other stakeholders is a critical factor affecting knowledge spread and consequently adoption. Our results provide crucial insights for the elaboration of an implementation action plan to boost the dissemination of feasible prevention measures against the cocoa swollen shoot virus disease in Ghana in order to efficiently cover farmers’ needs for information (technical advice) and inputs (access to hybrid seedlings). [ABSTRACT FROM AUTHOR]