Authors: EZERI, G.N.O.
Journal of Applied Sciences & Environmental Management, Vol. 6, No. 1, June, 2002, pp. 49-52
Abstract:
A herbicidal control of water hyacinth,WH (Eichhornia crassipes, Martius Solms – Laubach) was carried out by applying glyphosate (N – phosphyonomethyI glycerine) containing 360g/l glyphosate in the form of 480g/l isopropylamine salt at the rate of 2.16kg active ingredient (a.i/ha) by a fixed wing, AG-CAT Schweizer plane at the Ere fishing channel.
Pathological studies revealed that of the total number of fishes examined prior to the chemical application, 334 (5%) had fin-rot, 2541 (38%) abrasion, 802 (12%) lesions, 334 (5%) ulcerations, 1805 (27%) sloughing of their body slimc. None had tumours or nodules. The post application examination of fishes revealed that 5806 (7%) had fin-rot, 8294 (10%) abrasion, 4147 (5%) lesions, 1244 (1.5%) ulcerations and 4145 (5%) sloughing of body slime. None had tumours or nodules. The total number of fish that showed signs of infection prior to herbicidal application was 516 (86.9%) while it was 23,636 (28.49%) for post application of herbicide. The total number of fish caught prior to herbicidal treatment was 6,686 (7.46%) while a total number of 82,943 fish (92.54%) were caught after treatment. No fish mortality was observed throughout the post treatment monitoring. In this multi-disciplinary work, it was established that glyphosate at 2.16 a. i / ha controlled WH and associated weeds within four weeks of application without any intrinsic deleterious effect on fish and aquatic fauna. @ JASEM
Water hyacinth (Eichhornia crassipes) was first reported in Nigeria in 1984. It has been known to constitute a nuisance in Rivers Congo and Nile.
The project by African Development Bank-Economic Community of West Africa (ECOWAS) which began in 1992 revealed the spread, current weed status and control methods of Eichhornia crassipes which arrived Benin Republic in 1977 (ANPP, 1996). The weed, which was carried by water current into Nigerian waters, drifted from the neighbouring Republic of Benin. The Weed precisely came from Port-Novo creek, which has an entry in the sea around the Lagos Lagoon.
Water hyacinth (WH) in addition to being detrimental to the aquatic environment biologically, it physically blocks the waterways thereby impeding transportation and human activities. Their masses when adrift dislodge fishing nets in water resulting in huge financial losses to artisanal fisher-folk. WH also provides a hiding for snakes and other dangerous aquatic organisms.
Ere is a fishing village on the outlets of Yewa River to the Lagoon waters of Badagry Creek (OGADEP, 1991; Akinyemiju, et al, 1993). The World Bank in a recent survey estimated the loss due to WH in Nigeria to be a minimum of $500 million annually and therefore advised direct intervention as a measure to abate the menace of the weed (World Bank, 1990).