OBEN GAS DEVELOPMENT PROJECT

Chapter Three Description of Environment
3.2.5.5 Plant Pathological Assessment
A survey of the health status of wild plant species and economic crops in the project area revealed the
presence of fungal, bacterial and viral infections on the foliage of both categories of plants.
The prevalent pathological conditions are leaf spot and chlorosis, which were found in over 50% of the
specimens examined. Other diseases include necrosis, leaf mosaic, wet rot, and powdery mildew. The
causal organisms include Aspergillus spp., Fusarium spp., Penicillium sp. and Ganoderma
pseudoferreum among others. The severity index shown in Table 3.8 is based on the extent of spread
of the infection within a plant and among 5 – 10 plants in a population. When more than half of the
leaves on a single plant are infected, it is considered high; when more than five leaves in a group of 3 –
44 plants of the population are infected, it is considered moderate, while if only 1 or 2 leaves of plants
are infected it is considered a light infection.
Table 3.8: Plant Diseases, Causal Organisms and Severity Index of Infection in the Project Area
Nos. Plant Species Type of Disease Casual Severity % Freq.
Organism Index
1 Manihot esculenta Leaf mosaic ,Chlorosis Mosaic virus 2 30
2 Tefiria occidentalis Powdery mildew, leaf spot Oidium levea 3 60
3 Emilia coccinea Leaf spot Penicillium sp 1 20
4 Alcornea cordifolia Leaf spot Fusarium
moniliforme
2 30
5 Paspalum laxaum Necrosis, Leaf spot Aspergillus spp 1 20
6 Musa sapientum Chlorosis Cigar end Pseudomonas
andropogonii
Trachshaea
fructigena
1 20
7 Spigelia anthelmia Leaf spot, Chlorosis Penicillium sp.
Pseudomonas
fructigena
3 40
8 Panicum maximum Necrosis, Leaf spot Aspergillus niger
Penicillium sp.
1 30
9 Urena lobata Leaf spot Fusarium
oxysporium
2 10
Key to Severity Index: 0 = No infection, 1 = Light infections, 2 = Moderate infection 3 = Severe infection
3.2.6 Wild Life / Biodiversity Studies:
The Oben Field is located within Urhonigbe Forest reserve. This is however with approval from
appropriate government agencies. Moreover, virtually much of the forest reserve has been destroyed by
various kinds of human activities. Although no known data on wildlife exists for the Urhonigbe Forest
Reserve, some species of fauna including (insects, molluscs, amphibians, reptiles, birds and mammals)
were recorded during the current study (Table 3.9).
The invertebrate fauna were diverse and consisted of forest dwelling species dominated by ants,
beetles and millipedes. Many genera and species of arthropods (Ants, flies, butterflies and
grasshoppers) were recorded. Some species of bugs, dragon flies and damselflies were also recorded.
The Mollusca fauna was represented by the presence of the giant African land snail (Archachatina
marginata suturalis) and the garden snail, Limicolaria aurora.
Most of the mammals are crepuscular, feeding in the early hours of the day or just before dusk.
Rodents and pottos dominated the mammalian class. Forest dwelling species, seed and insect-eating
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