Effect of herbicidal control of water hyacinth on fish health at the Ere channel, Ogun State, Nigeria
Ezeri, G.N.O.
Journal of Applied Science and Environmental Management 6(1): 49-52
2002
Document Number: 259958
A herbicidal control of water hyacinth, WH (Eichhornia crassipes) was carried out by applying glyphosate (N-phosphyonomethyl glycerine) containing 360 g/litre glyphosate in the form of 480 g/litre isopropylamine salt at the rate of 2.16 kg 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, and 1805 (27%) sloughing of their body slime. 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 fishes that showed signs of infection prior to herbicidal application was 516 (86.9%) while it was 23 636 (28.49%) after herbicide application. The total number of fish caught prior to herbicidal treatment was 6686 (7.46%) while a total of 82 943 fishes (92.54%) were caught after treatment. Fish mortality was not observed throughout the post-treatment monitoring. In this multidisciplinary 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.