Resistance screening trials on coconut varieties to Cape Saint Paul Wilt Disease in Ghana

Abstract

The Cape Saint Paul Wilt Disease (CSPWD) is a coconut lethal yellowing type disease (LY) and is the single most serious threat to coconut cultivation in Ghana. The recommended disease management strategy is the cultivation of disease-resistant coconut varieties. More than 38 varieties have been screened for their resistance to CSPWD since 1956 and the results are reviewed in this paper. Two varieties, Sri Lanka Green Dwarf (SGD) and Vanuatu Tall (VTT), have shown high resistance to the disease, and their hybrid (SGD × VTT) is under observation to determine its performance. A programme to rehabilitate the CSPWD-devastated areas was started in 1999. Emerging results indicate that the MYD × VTT hybrid being used for the programme, succumbs to the disease under intense disease pressure. A redirection of the rehabilitation programme and the screening of more varieties are recommended.

Comparative PCR analyses for the detection of the Cape St. Paul wilt disease phytoplasma in coconut palms in Ghana

“…This is not surprising considering its economic lifespan and the fact that it was the first cultivar introduced into the West African coast by European explorers in the 16th century (Johnson & Harries, ). The MYDxVTT hybrid was approved for replanting devastated fields in the late 1990s after resistant trials showed that it was moderately tolerant to the CSPWD (Dery et al., ; Quaicoe et al., ). However, data on the replanting revealed that the MYDxVTT hybrid was susceptible to high disease pressure (Quaicoe et al., ).…”

“…The MYDxVTT hybrid was approved for replanting devastated fields in the late 1990s after resistant trials showed that it was moderately tolerant to the CSPWD (Dery et al., ; Quaicoe et al., ). However, data on the replanting revealed that the MYDxVTT hybrid was susceptible to high disease pressure (Quaicoe et al., ). Results indicated that the Central Region was the most CSPWD‐affected region based on the highest percentage of detection of the CSPWD phytoplasma by PCR.…”

Coconut Lethal Yellowing Diseases: A Phytoplasma Threat to Palms of Global Economic and Social Significance

“…The most commonly recommended strategy for use is planting a range of resistant varieties in any growing area to reduce the risk of widespread plantation death should plant resistance be eroded by adaptation in the pathogen or vector population. Problems have occurred where varieties that have previously been reported as resistant have shown symptoms indicating a resistance breakdown (Broschat et al, 2002; Been and Myrie, 2005; Quaicoe et al, 2009). Variety improvement and evaluation needs to take place locally because resistance has been demonstrated to have a degree of site specificity; potentially due to the influence of environmental factors (Quaicoe et al, 2009; Odewale et al, 2012) and genetic differences between phytoplasma populations.…”

“…Problems have occurred where varieties that have previously been reported as resistant have shown symptoms indicating a resistance breakdown (Broschat et al, 2002; Been and Myrie, 2005; Quaicoe et al, 2009). Variety improvement and evaluation needs to take place locally because resistance has been demonstrated to have a degree of site specificity; potentially due to the influence of environmental factors (Quaicoe et al, 2009; Odewale et al, 2012) and genetic differences between phytoplasma populations. The short generation times and small, repetitive genomes of phytoplasmas favor adaptation.…”

“…Cape Saint Paul Wilt Disease (CSPWD) in Ghana has been addressed by resistance screening work using a hybrid of Sri Lanka Green Dwarf (SGD) and Vanuatu Tall (VTT) which is being used for replanting following the disease epidemic (Quaicoe et al, 2009). Similarly, in Jamaica, after devastating losses to LYD, the local Jamaican tall variety was widely replaced with the Malayan dwarf varieties and MayPan, which led to a recovery of the coconut industry (Been, 1995; Harrison et al, 2002a).…”