Diseases of Plantation Forestry Trees in Southern Ghana

Apetorgbor M Mamle,Roux Jolanda

doi:10.33687/phytopath.004.01.0908

Abstract

Ghana is on the verge of exhausting its timber resources and has embarked on reforestation. However, the establishment of pure stands of high value indigenous tree species such as Odum (Milicia excelsa and M. regia), Mahogany (Khaya and Entandrophragma species) and Kokrodua (Pericopsis elata) were not successful as a result of insect pest and disease problems. These failures, together with the need to establish plantations partly account for the widespread planting of teak (Tectona grandis), cedrela (Cedrela odorata) and other introduced tree species. Disease outbreaks in Tectona grandis, Cedrela odorata and Ceiba pentandra have been observed with the expansion of plantation estates. A study was therefore conducted to identify key diseases occurring in tree plantations, determine their distribution and evaluate management strategies to contain them. Diseases encountered include root rot caused by Armillaria hemii on T. grandis and Cedrela odorata, leaf spot and dieback on Ceiba pentandra seedlings and saplings caused by Colletotrichum capsici, Fusarium solani and Lasiodiplodia theobromae, stem canker on Eucalyptus spp. caused by Botryosphaeria sp. and leaf blight caused by a Calonectria species. Management of these diseases will require training of foresters on tree health issues, quarantine and silvicultural practices and initiation of sound breeding and selection programmes.

Highlights

Ghana has one of the highest rates of deforestation in West Africa (Benhin and Barbier, 2001)
Colletotrichum capsici was isolated from the leaf spot while Fusarium solani and Lasiodiplodia theobromae were found associated with dieback of stems in both the nursery and field (Apetorgbor et al, 2003a)
Field survey: The surveys were on Tectona grandis and Cedrela odorata plantations in all the forest reserves, Eucalyptus species in African Plantations for Sustainable Development (APSD) and Ceiba pentandra plantations and nurseries in the Afram Headwaters, Jimira and Pra Anum forest reserves from 2006 to 2012 (Figure 1, Table 1)

Summary

INTRODUCTION

Native species such as Tectona grandis, Cedrela odorata, Gmelina arborea, Pinus caribaea and Eucalyptus spp. with T. grandis alone constituting well over 70%. Colletotrichum capsici was isolated from the leaf spot while Fusarium solani and Lasiodiplodia theobromae were found associated with dieback of stems in both the nursery and field (Apetorgbor et al, 2003a). During disease surveys of Eucalyptus grandis, E. camaldulensis and E. dagambae plantations in the Ashanti, Central and Eastern Regions of Ghana, stem cankers on mature E. dagambae, which resemble that caused by species of Chrysoporthe were observed in a single compartment near Kumasi (Roux and Apetorgbor, 2009). Plantation developers reported that disease problems in these plantations are increasing in the Anhwiaso South, Kwamisa, Opro, Tano Nimri, Mamiri and Afram Headwaters forest reserves (Apetorgbor and Bosu, 2009). Field survey: The surveys were on Tectona grandis and Cedrela odorata plantations in all the forest reserves, Eucalyptus species in APSD and Ceiba pentandra plantations and nurseries in the Afram Headwaters, Jimira and Pra Anum forest reserves from 2006 to 2012 (Figure 1, Table 1). Fungal colonies were isolated using identification keys (Brayford, 1997; Rivarden et al, 1994; Arora, 1986) as well as DNA sequence data (IGS and ITS gene regions)

RESULTS

DISCUSSION

CONCLUSIONS