Cocoa Swollen Shoot Virus Disease Research Articles

Determinants of the Adoption of Additional Livelihoods among Smallholder Cocoa Farmers in the Sefwi Akontombra Cocoa District of Ghana

Although the production of cocoa in Ghana sustains the economy, its quantity has not been stable in the past. This instability in the quantity of cocoa produced can be attributed to climatic conditions and other human-induced factors such as Galamsey. In the Sefwi Akontombra cocoa district, one leading cause of the reduction of cocoa is the infestation of the Cocoa Swollen Shoot Virus Disease (CSSVD). Farmers Business School has been one medium through which farmers are educated on how to make farming a business however, various factors seem to limit farmers decisions to adopt these additional livelihoods. Hence, the main objective of the study was to explore the various factors that hindered farmers' decision to adopt additional livelihoods. Employing the simple random sampling method, 410 farmers were selected for the study. A binary Logistic regression model was employed to establish relationships between Additional Livelihoods and the various factors that hinder its adoption. The study revealed that Good Agronomy Practices such as annual pruning, annual fertilizer application, and annual pollination were practiced by farmers. Regardless of this GAP, the quantity of cocoa beans produced annually per hectare has been reduced from 2017 to 2021. The study also revealed that farmers who have adopted additional livelihoods have their income level increased, food security, and general livelihood increased. Most of the farmers (70.7%) were not regular at Farmers Business School which seems to be a reason why the majority have not adopted additional livelihoods. Other factors such as environmental, socio-cultural, and economic were significant at 0.05 significant level. However, personal factors were not significant at either 0.1, 0.05, or 0.01. The study recommends that farmers should be frequent participants in Farmers Business School.

Improving Support Systems for Cocoa Farmers beyond Cocoa Swollen Shoot Virus Disease Infestation

Cocoa swollen shoot virus disease (CSSVD) has severely hampered the production of cocoa in Ghana since pre-colonial days. The Ghana Cocoa Board has put several measures in place to support cocoa farmers in the fight against the CSSVD. This present study captures how the CSSVD affects cocoa farmers and the support systems for such situations. Using a survey design, the study employed the multi-stage sampling technique to select 413 cocoa farmers. A structured questionnaire was used to seek information from the cocoa farmers. A multiple linear regression model was estimated to analyse the data. The CSSVD affects the living standards of cocoa farmers through their economic wellbeing, thus, household income and assets accumulation. The social wellbeing of farmers is also affected by the CSSVD through their socio-cultural (participation in cooperatives and communal activities) and educational activities (participation in extension education activities). The implication is that the current support systems given to cocoa farmers after being affected by the CSSVD need to be strengthened, enhanced and made holistic to cover their economic and social wellbeing. Economic and social interventions aimed at increasing the resilience of cocoa farmers in the face of the CSSVD will be helpful in this direction.

Field evaluation of the impact of cocoa swollen shoot virus disease infection on yield traits of different cocoa (Theobroma cacao L.) clones in Ghana.

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.

Inconsistent PCR detection of Cacao swollen shoot virus (CSSV) is linked to the occurrence of different variants across the cocoa regions of Ghana

Reliable diagnostic tools capable of detecting latent and asymptomatic infections are critically important to support the management of the cocoa swollen shoot virus disease (CSSVD) and also to complement research activities on screening for resistant cocoa varieties. Development of efficient polymerase chain reaction (PCR) assays sensitive for detection of CSSV infections has thus been a major research focus over the years. Advances in the full genome sequence information have resulted in the design of several Cacao swollen shoot virus (CSSV)-specific and degenerate primers. The objective of the present study was to further assess the detection efficiency of ten (10) of the most utilized and novel CSSV primers on isolates of the virus across Ghana. Results from the PCR assays showed a highly variable and poor efficiency of the primers on the 189 samples of CSSV isolates evaluated. The overall detection potential of the primers ranged from 4 % to 23 % with the four best performing primers in terms of PCR positivity being P4 (23 %), CSSD1 (21 %), JOEL (21 %) CSSD2 (19 %) and BADNA (19 %). The generally poor and inconsistent efficiency of the primers are discussed in the context of the genetic variability and also the occurrence of new variants of the virus in Ghana.

Effects of cocoa swollen shoot virus disease (CSSVD) on the welfare of cocoa farmers in Ghana: evidence from Chorichori community of the Sefwi Akontombra district

Effects of cocoa swollen shoot virus disease (CSSVD) on the welfare of cocoa farmers in Ghana: evidence from Chorichori community of the Sefwi Akontombra district

Effectiveness of the eradication campaign of cocoa swollen shoot virus disease in Ghana: the extension and implementation problem

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.

Evaluation of mild strain cross protection in cacao – further evidence of the protective potential of cacao swollen shoot virus strain N1 against the New Juabeng (1A) isolate under field conditions

The yield, canopy status and cocoa swollen shoot virus disease (CSSVD) symptom severity were assessed in cacao trees in a long-term field experiment originally established to study cacao swollen shoot virus strain 1A (CSSV-1A) epidemics in plots inoculated with the mild strain CSSV-N1. Yield of cacao was 73.7% and 32.1% lower in cacao plants inoculated with CSSV-1A and the non-inoculated respectively, when compared with cacao plants inoculated with CSSV-N1. CSSVD severity and canopy cover of cacao plants were significantly (P < 0.0001) affected by varying the number of inner rows inoculated with CSSV-N1 as well as individual CSSV strains. The treatments in which all the test cacao trees or first five inner rows received mild strain cross protection (T4 and T1) had the best canopy and lowest disease severity. Trees with CSSV-N1 protection had better canopy and lower CSSVD severity in comparison with the non-inoculated and CSSV-1A inoculated trees. DNA fingerprinting analysis indicated that genetic make-up of the planting material does not appear to contribute significantly to variation in disease severity or canopy status. Significant relationships were established between some soil parameters and CSSVD symptom severity (organic carbon, phosphorus, calcium, nitrogen, magnesium) as well as canopy status (phosphorus, potassium, magnesium).

Farmers’ adoption of preventive and treatment measures of cocoa swollen shoot virus disease in Ghana

Abstract Cocoa Swollen Shoot Virus Disease (CSSVD) has been of great threat to the Ghanaian cocoa industry since 1936. Eradication by cutting out and replanting of affected cocoa farms has been the main method of controlling the disease in Ghana. Also, considerable research efforts have yielded several recommendations that farmers are expected to implement to limit the spread of the disease. However, the disease keeps spreading to new areas at an increasing rate. This study is the first to assess the depth and extent of farmers' adoption of recommended preventive and treatment measures respectively. We explore the rate of adoption and factors that affect the probability and depth of adoption of the recommended preventive measures, as well as the willingness of cocoa farmers to treat affected farms by eradication. Results showed that farmers' awareness of the recommended preventive measures significantly influenced both the probability and depth of adoption of these measures. The extent of adoption of recommended treatment procedures was very low (5%). It is therefore, recommended that the Ghana government through the Cocoa Board focuses on intensive farmer education and information dissemination through extension to increase farmer knowledge and awareness of the recommended preventive measures and treatment procedures. Also, factors such as farmers' knowledge of the causal agent, effects of the disease on cocoa, farmers’ perception of the environment (i.e., whether neighbouring farms have been affected and land tenure arrangements) and adoption of a preventive measure significantly influenced farmers’ willingness to treat CSSVD affected farms. These factors should be considered in packaging the recommended technologies and the strategy for information dissemination.

The Use of 3S Technology to Assess Cocoa Swollen Shoot Virus Disease in Offinso Cocoa District Area, Ghana

The cocoa industry is ruined by Cocoa Swollen Shoot Virus Disease (CSSVD) caused by a virus transmitted by mealybugs. Initiatives by Ghana Cocoa Board to control the disease have not been all that successful over the years. The study aimed at exploring Geographic Information System (GIS), Remote Sensing (RS), and Global Position System (GPS) techniques to assess the prevalence of CSSVD in terms of their geographic locations by comparing the 2nd and 3rd Country Wide Surveys (CWS) undertaken by Cocoa Health and Extension Division (CHED) in the Offinso cocoa district of Ghana. Handheld GPS, GIS shapefiles, and Landsat 7 and 8 satellite images were used. Geo-spatial overlay operations of shapefiles and performances on NDVI computations yielded relationships between the 2nd and 3rd CWS on CSSVD farms over ten years period from 2009 to 2019. It was revealed that only 12.99 hectares of the disease are found in the 2nd CWS was persistent under the 3rd CWS and this was due to successful treatment of infected area during the 2nd CWS. Also, the health of cocoa under the 3rd CWS had improved to 262.89 hectares from the previously infected 275.89 hectares. Thus, treatment of the CSSVD was effective and the vegetative health index of the farms emanated from the treatment was also encouraging. The results show the impact on the control of CSSVD for the sustainable production of cocoa. In addition, the research method serves as a guideline for other related studies in an attempt to investigate, quantify and project CSSVD.

Determinants and Policy Ramifications of Cocoa Farmers’ Use of Agrochemicals in Cocoa-Based (Theobroma cacao) Agroforestry Systems in Cameroon

The application of agrochemicals in agroforestry systems in general and cocoa-based agroforestry systems in particular is unprecedented as agroforestry systems are considered as environmentally benign, agro-ecological and sustainable agricultural systems. It was within this context that this study was undertaken to examine the determinants of cocoa farmers’ use of agrochemical in cocoa-based agroforestry systems. Through a mixed research approach, and data analysis using appropriate descriptive and inferential statistical tools, it was found that the main types of herbicides used by cocoa farmers in cocoa-based agroforestry systems are Paraquat (50%) and Glyphosate (40%). For fungicides, the main types used were Mancozeb (70%), Maneb (65%), Ridomil (60%), Caocobre (50%), and Nordox (40%). For insecticides, the main types used were Methyl (65%), Imidacloprid (60%), Endosulfan (50%), Cypermethrin (50%), and Fenobucarp (40%). The most common pests and diseases affecting cocoa perceived by cocoa farmers in cocoa-based agroforestry systems were Black pod – Phytophtora spp (100%), Capsid/Mirids – Distantiella theobroma and Sahlbergella singularis (100%), Cocoa Swollen Shoot Virus Disease – CSSVD (60%), Witches’ broom – Crinipellis perniciosa (50%) and Vascular streak dieback (40%). Most cocoa farmers perceived that the use of all three agrochemicals (herbicides, fungicides, and insecticides) in cocoa-based agroforestry systems have negative socio-economic and environmental impacts. From Spearman rank correlation and logistic regression coefficients, it was noticed that the main explanatory variables having a statistically significant direct non-cause-effect and cause-effect relationship (p&lt;0.05) with cocoa farmers’ use of agrochemicals in cocoa-based agroforestry systems were gender, income, availability of agrochemicals, access to information, membership in farming groups, and access to extension services. Meanwhile the main explanatory variables having a statistically significant indirect or inverse non-cause-effect and cause-effect relationship (p&lt;0.05) with cocoa farmers’ use of agrochemicals in cocoa-based agroforestry systems were farm size and number of farms. It is recommended that policy makers take a critical look at the different agrochemicals used by cocoa farmers as well as the determinants of their use when formulating policies geared towards ensuring the sustainable use of these agrochemicals in cocoa-based agroforestry systems.

Spatiotemporal Spread of Cacao Swollen Shoot Virus Severe Strain 1A in Mixed Hybrid Cacao Pre-inoculated With Mild Strain N1.

The spatiotemporal spread of cocoa swollen shoot virus disease (CSSVD), which is caused by cacao swollen shoot virus (CSSV) severe strain 1A in mixed hybrid cacao pre-inoculated with CSSV mild strain N1 (CSSV-N1), was investigated during a field experiment from 2006 to 2017, at the Cocoa Research Institute of Ghana. The development of disease epidemics has been described by the use of statistical modeling. Protecting all cacao plants with CSSV-N1 reduced the rate of CSSV-1A symptom appearance by 43% (P = 0.05) compared with the nonprotected control and by 33% compared with plots where cacao plants in the outer three or five rows were protected with CSSV-N1. Similarly, creating the protective outer rings three or five rows deep reduced the rate of CSSV-1A symptoms by 14% (P = 0.05) compared with the nonprotected control. CSSV-1A epidemics increased approximately 18% faster (P = 0.05) in transects oriented from the north and east compared with those oriented from the south and west. During the last 2 years of the study, CSSVD spread decreased significantly (P = 0.05) faster in plots where all test cacao plants were inoculated with CSSV-N1 compared with other treatments. The growth of cacao did not differ significantly among the treatments over the 9-year assessment period. Similarly, differences in the cumulative yield among the treatments over the 8-year assessment period were not significant.

Social network to inform and prevent the spread of cocoa swollen shoot virus disease in Ghana

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).

Assessment of genetic diversity and structure in cocoa trees (Theobroma cacao L.) in Côte d’Ivoire with reference to their susceptibility to Cocoa swollen shoot virus disease (CSSVD)

Resistance to Cocoa Swollen Shoot Virus disease (CSSVD) is becoming an increasingly important criterion for selection of new cocoa cultivars in Cote-d’Ivoire, where the disease resurfaced since 2003. This virus can seriously affect the yield of trees with a loss of 25%, 1 year after infection, to around 100% 3 years after. In order to find tolerant plant material, 337 farm accessions have been collected on fields affected by CSSVD, according to the status of accessions potentially tolerant (APT) or susceptible (APS). Both phenotypic groups were genotyped using 30 microsatellite markers (SSR) in the presence of representative clones of the ten genetic groups of cocoa. This study revealed 214 alleles with the set of primer pairs used. The number of alleles per locus was between 3 and 16 with an average of 7.13 alleles per locus. The results showed a high contribution of genetic diversity within population (Hs = 0.51) to the total genetic diversity (Ht = 0.53) for the two studied groups. There was no significant difference between tolerant and susceptible groups (Fst = 0.05). These results suggest that APT could be a potential genetic reservoir for other traits of interest associated with virus resistance. The phylogenetic tree, as the STRUCTURE analysis of Ivorian cocoa population, showed a distribution of individuals following four groups marked by a high contribution of group 4 (Nanay, Maranon, Guiana) followed by group 2 (Criollo), and group 1 (Amelonado), and a lower contribution of group 3 (Iquitos, Purus, Nacional, Curaray, Contamana).

The effects of mild cacao swollen shoot virus strains N1 and SS365B on growth and yield of cacao

A field experiment started at the Cocoa Research Institute of Ghana in 2007 to investigate the effects of the cacao swollen shoot virus (CSSV) mild stains N1 and SS365B on growth and yield of mixed hybrid cacao (Theobroma cacao L.). Growth was significantly influenced by the duration of infection with the two CSSV mild strains. Slicing analyses showed no significant differences in stem circumference among treatments up to the third year of field data collection. However, from the fourth to the seventh year, growth of N1-inoculated cacao plants was significantly higher than that of SS365B-inoculated plants. Overall, growth did not differ significantly between cacao plants inoculated with mild strain and the non-inoculated plants. Contrary to some previous reports, yield of mild strain-inoculated cacao plants was significantly lower than that of the non-inoculated plants. Polymerase chain reaction was used to detect the presence of CSSV in randomly selected field samples. The implications of these results (based on field data collected from 2008 to 2014) in the management of cocoa swollen shoot virus disease in Ghana are discussed.

Agroforestry systems can mitigate the severity of cocoa swollen shoot virus disease

Currently, the only effective treatment for cocoa (Theobroma cacao L.) infected with the cocoa swollen shoot virus disease (CSSVD) is to cut and replant infected trees. Hence, the development of preventive control measures and strategies to mitigate the severity of the disease are of utmost importance. While past research has mainly focused on resistance breeding, mild strain cross protection and vector control, diversification measures such as agroforestry have received relatively less attention, despite their potential to mitigate CSSVD severity. Therefore, we studied the effects of shade on CSSVD symptom severity, capsid damage and cocoa yield along a gradient of increasing shade tree abundance in smallholder cocoa farms in Ghana. Furthermore, we measured photosynthetic active radiation and assessed soil fertility in order to elaborate on potential causal factors for possible shade effects on CSSVD symptom severity. Both CSSVD symptom severity and cocoa yields followed quadratic curves, and were found to be lowest and highest in plots with 54% and 39% shade, respectively. The simulated optimal shade levels for CSSVD symptom severity and cocoa yield overlapped between 45%–53%, indicating that agroforestry systems with around 50% shade cover may be an optimal coping strategy to balance CSSVD symptom severity versus reduced cocoa yield until diseased cocoa is replaced with more resistant varieties. Furthermore, our results suggest that rather than soil fertility, high-light and possibly also soil moisture stress may have been responsible for the shade effects on CSSVD symptom severity.

Combatting Cocoa Swollen Shoot Virus Disease: What do we know?

Cocoa Swollen Shoot Virus Disease (CSSVD) is one of the major factors limiting cocoa (Theobroma cacao L.) productivity in West Africa. The only cure for CSSVD is to cut out visibly infected trees and the official eradication campaign in Ghana has cut out more than 200 million trees since 1946. 80 years of research on preventive control measures have mainly focused on resistance breeding, mild strain cross-protection (inoculation of cocoa seedlings with a mild strain of the virus to protect against the severe strain) and control of mealybug vectors. Meanwhile, diversification measures such as agroforestry (for shading) or barrier (strip) cropping have received less attention. Despite promising results, CSSVD is more prevalent in the field than ever before. The large body of knowledge on preventive control measures for CSSVD is fragmented and many publications are not easily accessible. Furthermore, the literature has never been systematically evaluated and quantitatively assessed. Hence, we consolidated this knowledge with an extensive literature review followed by meta-analysis to identify the pertinent research gaps. Out of 423 publications on CSSVD-related issues, we selected 34 studies, which contained 52 datasets on seven different preventive control measures. Results showed that resistance breeding and mild strain cross-protection may reduce CSSVD infection by 30 percent, while the potential of diversification measures (shading/agroforestry and barrier (strip) cropping) seems to be considerably higher (40 and 85 percent, respectively). However, there is a lack of evidence because of a low number of studies about diversification measures, indicating that our results have to be interpreted with care and calling for more research in this area. Future testing is needed to evaluate the efficacy of barrier (strip) cropping to reduce CSSVD, and address the effect of shade on CSSVD symptom severity. Furthermore, the practical relevance of different preventive control measures for farmers needs to be assessed, and shade should be considered in current breeding programs for CSSVD resistance.

History and Data Analyses of ‘Cutting Out’ Method for Cocoa Swollen Shoot Virus Disease (CSSVD) Control in Ghana

Cocoa swollen shoot virus disease (CSSVD) has for over seven decades been managed in Ghana through the ‘cutting out method’. This procedure involves complete removal of infected cocoa trees together with neighbouring apparently healthy cocoa trees from affected farms and replanting with improved cocoa varieties tolerant to the virus. This method of control started in 1946 with the objective to eradicate and also limit the spread of the virus to only severely affected farms in Ghana. Farmers whose farms are ‘cut out’ of infected cocoa trees are assisted to regenerate their farms with improved cocoa varieties tolerant to the virus. In practice however, this approach have several times been opposed by farmers leading to its intermittent suspension. Farmers rather prefer to allow CSSV infected trees to remain on their farms to produce few pods as source of income than to allow them to be removed. Delayed funding of the programme coupled with or without payment of monetary compensation to farmers often results in time lags between outbreak identification and farmers willingness to allow infected trees to be removed. This among other challenges of the programme have accounted for the increased prevalence and the continuous spread of the disease in Ghana. This paper provides empirical analysis of cocoa tree removals from 1945/46 to 2013/2014 when the programme has been continuously implemented across the cocoa regions in Ghana and discusses some of the key challenges on the implementation of the ‘cutting out’ method and offers some perspectives for its use to manage the spread of the disease.

Genetic variation among cocoa (Theobroma cacao L.) families for resistance to cocoa swollen shoot virus disease in relation to total phenolic content

AbstractPhenolic compounds have been suggested as one of the defence mechanisms to cocoa swollen shoot virus disease (CSSVD), but not well studied. Correlation and genetic variation of total phenolic content (TPC) and CSSVD resistance among 53 cocoa families were investigated. Three‐month‐old seedlings of 15 families obtained from an incomplete 6 × 3 NCII mating design, of 24 families from a 3 × 8 NCII mating design and of 14 other families were evaluated for CSSVD and TPC. Plants were inoculated with viruliferous mealybugs carrying the New Juaben CSSV strain (1A) in a gauze house facility. A single seedling randomization within blocks procedure was followed, using the gauze house units as blocks. There were six blocks with five seedlings of each family randomized within each block. Disease severity scores on leaf flushes at the first, second, third and seventh flushes after inoculation were recorded. The TPC before and 3 months after inoculation was also determined. Family effects were highly significant (P ≤ 0.01) for CSSVD severity scores and TPC. Narrow‐ and broad‐sense heritability estimates were low for CSSVD severity but moderate to high for TPC evaluations. Correlations between severity scores and TPC were weak (r = −0.22 to 0.40) suggesting that the TPC may be of little value in selecting CSSVD resistance varieties in cocoa. Additive effect in terms of significant GCA was important for CSSVD severity scores whereas both additive and non‐additive effects were important for TPC values when the 3 × 8 and 6 × 3 NCII mating designs were analysed. Only clones GU 239/H, GU 290/H and GU 225/V had favourable GCA effects for CSSVD symptom expression indicating their potential for developing progeny with high levels of resistance to CSSVD infection.

First Record ofPseudococcus jackbeardsleyi(Hemiptera: Pseudococcidae) from Africa, Côte d'Ivoire

Cocoa swollen shoot virus disease is an important virus disease of cocoa occurring mainly in West Africa. Mealybugs are known to be vectors of the pathogen, Cacao swollen shoot virus. Since recent outbreaks in Côte d'Ivoire, studies have been undertaken on different aspects of the disease. During 2013, surveys were conducted to identify mealybug species infesting aerial parts of cocoa (Theobroma cacao L.; Malvales: Malvaceae) trees at various sites and the samples were authoritatively identified using morphological characters. A species new to Africa, Pseudococcus jackbeardsleyi Gimpel & Miller (Hemiptera: Pseudococcidae), was found at 2 localities in Côte d'Ivoire, i.e., Buyo (Soubré county) and Gbalékro (Agboville county). Hosts of this polyphagous mealybug belong to 47 plant families and include banana, eggplant, Hibiscus spp., potato, sweet pepper and tomato. Virus transmission by P. jackbeardsleyi has not been recorded, but it belongs to the same genus as P. maritimus (Ehrhorn), which transmits Little cherry virus 2 to sweet cherry, and P. longispinus (Targioni Tozzetti), which transmits Grapevine A trichovirus (GAV) to grapevine and Cacao swollen shoot virus (CSSV) to cocoa. The introduction and establishment of P. jackbeardsleyi in Africa may have a considerable impact on both commercial and subsistence agriculture.

An evaluation of gains in breeding for resistance to the cocoa swollen shoot virus disease in Ghana

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.