CSIR – FORESTRY RESEARCH INSTITUTE OF GHANA

Pests and diseases of Cedrela odorata

plantations in Ghana

Apetorgbor, M. M., Bosu, P. P., Nkrumah, E. and Roux, J.

16th -18th Sept. 2014

April 18, 2023

Forestry Research Institute of Ghana

Background

In Ghana, cedar (Cedrela odorata) and teak (Tectona grandis) plantations constitute

70-80% of the total forest plantation estate. The total area covered by cedrela plantations

was quite small. However, there has been a steady increase

in demand of timber since the beginning of the Forest Plantation Development Programme in 2001.

April 18, 2023

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Background (Contd)

The preference of cedrela as the species of choice for plantation development may be attributed to the relatively higher growth rate compared to

native species high tolerance of diseases and pests.

However, recent occurrences indicate that plantations of cedrela are no longer as less prone to disease and pest outbreaks.

April 18, 2023Source: Apetorgbor and Bosu, 2009

Forestry Research Institute of Ghana

Background (Contd)

The level of outbreak of diseases and pests in these timber resources is increasing gradually.

Reports have been received on dieback in two to four-year-old cedrela plantations in different parts of Ghana.

Armillaria fuscipes is the main cause of basal root rot in cedrela trees among others in the Ethiopian plantations.

However, the causal agents responsible for the attack of cedar plantations in Ghana are not known.

April 18, 2023Source: Apetorgbor and Bosu, 2009

Forestry Research Institute of Ghana

Objectives

To examine the extent and severity of the outbreaks in the affected plantations

To identify the causal agents and evaluate management options.

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Site Description

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Methodology

Cedrela plantation trees were established under taungya at 3m x 3m spacing

Inter-planted with plantain, cocoyam and cassava except in the Mamiri forest reserve where trees were interplanted with Cacao theobromae.

At Mesewam Research Station, Cedrela trees were planted intermixed with Khaya ivorenses

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Field assessment and pests and disease sampling

Symptoms, number and distribution of affected trees within the plantations were recorded.

Three replicates of each plantation was sampled to assess the extent of damage within plantations

Attacked trees were classified using a five-point damage rating: Healthy (no visible sign of disease/attack) Minor (<5% of trees with symptoms on evident on bole,

but tree shows no sign of damage) Moderately damage (<20% of trees with symptoms

evident on bole, leaves necrotic and/or dropping, sap flow)

April 18, 2023

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Field assessment and pests and disease descriptions (Cont’d)

Severe (>75% of infected trees completely

defoliated, heavy flow of sap Dead trees

Samples of infected stems and roots, insects and other potential arthropod vectors were sampled for laboratory analyses.

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Isolation of causal agents affecting trees

Small pieces from diseased roots, barks and stems were transferred on to Malt Extract Agar and Potato Dextrose Agar growth media to isolate Fungi Imperfecti

Basidiomycetes isolated using a Selective medium containing benomyl and streptomycin

Fungal colonies appearing on media were identified using identification keys and DNA sequence data (IGS and ITS gene regions)

April 18, 2023

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Cont’d

Samples of symptomatic trunks of cedrela trees with pinholes were placed in moist chamber to trap insects causing infestations.

Adult insects and crawling larvae that appeared were photographed and identified.

April 18, 2023

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Chemical control attempts

Recommended dosage of insecticide, Dursban (480g/l Chlorpyrifos) combined with fungicide, Kocide (77% Copper hydroxide) were applied to the trunks of moderately infested Cedrela trees in three replicates of 50m x 50m plots

Spraying was repeated 6 months later before the onset of the rains in the Anwhiaso South Forest Reserve

April 18, 2023

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RESULTS

04/18/23

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Cedrela pest and disease outbreaks in forest reserves in Ghana

Forest reserve/Research Station

Ecological zone

Age (Yrs)

Health status Disease/insect pest severity

Causative agent/Pest

Distribution of disease/pest

Asubima DS 1-2 Mortality Minor Drought Isolated

Afram Headwaters

DS

1-2

Wind throwing Moderate Drought/Hardpan Isolated

Insect pest infestation

Severe Apate sp. Isolated

Mesewam MS 9 Insect pest infestation

Moderate Apate sp. Isolated

Yaya MS

1-2

Defoliation Moderate Drought/Hardpan Scattered

Stunting Minor Drought Scattered

Mamiri ME-WE 9 Basal rot/Insect pest infestation

Severe Monochamus ruspator and Rhopalizus nigripes/ Armillaria hemii

Scattered

DS: Dry Semi deciduous; MS: Moist semi deciduous; ME-WE: Moist Evergreen-Wet Evergreen

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Cedrela pest and disease outbreaks in forest reserves in Ghana (Cont’d)

Forest reserve/Research Station

Ecological zone

Age (Yrs)

Health status Disease/insect pest severity

Causative agent/Pest

Distribution of disease/pest

Tano Nimiri ME-WE 9 Basal rot/insect pest infestation

Severe Monochamus ruspator and Rhopalizus nigripes/ Armillaria hemii

Scattered

Anwhiaso South MS 7 Insect pest infestation

Moderate Apate sp. Isolated

Worobong South DS

8

Insect pest infestation

Minor Apate sp. Isolated

Wind throwing Minor Drought/Hardpan Isolated

DS: Dry Semi deciduous; MS: Moist semi deciduous; ME-WE: Moist Evergreen-Wet Evergreen

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Field assessment (Insect attacks)

Straight clean boles, greyish bark, narrowly buttressed base

Barks, turns brownish as though charred by fire along bole

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Pin holes spread on trunk,Initial attack trigger sap flow

Continuous sap flow turns brownish and cankerous

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Field assessment (Disease attacks) Basal root disease found in two out of the seven forest

reserves Disease incidence was severe and scattered in plantations. About 68.3% of the plantation were affected Affected trees cleared, resulting in huge economic losses to

developers.

April 18, 2023

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Basal rot and dieback in Cedrela odorata

Yellowing of leaves as a result of basal rot Dead cedar tree

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White mycelial fans between bark and woodCracks at the base of tree trunk

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Mixed plantations in Research plots

Tree Health Status

Insect pest infestation in plantation comprising of

11% Khaya sp.89% Cedrela odorata

25% Khaya sp.75% Cedrela odorata

50% Khaya sp.50% Cedrela odorata

Healthy 76.8 89.2 100

Moderately infested

15.9 0 0

Severely infested

2.9 10.8 0

Death of trees 4.4 0 0

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Mono-plantations

Tree Health Status

Insect pest infestation and disease incidence in Cedrela odorata plantations in

Mamiri Tano Nimri Anhwiaso South

Healthy 31.7 13.0 96.2

Moderately infested/diseased

14.5 4.1 1.8

Severely infested/diseased

36.5 61.6 1.0

Death of trees 

16.1 21.3 1.0

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Causal agents affecting trees

Insect pests on Cedrela odorata trees

Monochanus ruspator F. Rhopalizus nigripes Chevr.

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Causal agents affecting trees (Cont’d)

Armillaria heimii mycelial fans in between cambium between bark and wood of affected Cedrela trees

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Chemical control attempt in the field

Infested Cedrela trees Recovered Cedrela trees

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Conclusions

Insect pests and disease of C. odorata are potential threat to plantation development efforts in Ghana.

Control may require Integrated approach involving routine monitoring and surveillance in plantations

throughout the country, provenance trials to select disease resistant varieties, matching of Cedrela to appropriate sites during plantation

establishment and suitable silvicultural interventions.

April 18, 2023

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Acknowledgement

Funding for this research and survey was provided by the African Development Bank (AfDB) and Forestry Commission

We thank Dr. V. K. Agyeman, Director of FORIG for his efforts in accessing the funds for this study.

Agricultural Biotechnology Institute (FABI), University of Pretoria for fungal identification

Mr Quarm who made his farm available for the survey and research

Messrs Seth Nuamah, John Mensah and Ms. Ewuramma Antwiwaa for their technical support

April 18, 2023

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Thank you