COMPARATIVE EFFECT OF HERBICIDAL AND NON-CH^1EMICAL CONTROL METHODS AGAINST WATER HYACINTH

The invasion of water hyacinth in the fresh water bodies has resulted in tremendous ecological and economic losses globally. In Pakistan water hyacinth is wide spread due to the unawareness of the masses and negligence of the scientific community, causing alteration of ecosystem services, deterioration of aquatic environments and spread of water related diseases. Water hyacinth infestations have also led to enormous economic losses in Pakistan by impeding water flows and hydroelectricity facilities. To investigate the efficacy of different control measures, an experiment was carried out during spring 2014. The experiment was laid out in randomized complete block (RCB) design with three replicates. Eight treatments including (i) 2, 4-D ester @ 1.5 kg a.i. ha-1, (ii) paraquat @ 1.5 kg a.i. ha-1(iii) glyphosate @ 2.0 kg a.i. ha-1, (iv) water extract of Parthenium hysterophrous and (v) water extract of Sorghum bicolor L. @ 1: 10 (w/v), (vi) black plastic, (vii) hand weeding and (viii) a weedy check for comparison. All the variables except species abundance were significantly affected by various methods of weed control. Minimum plant height of water hyacinth (0.00 cm) was recorded in the hand weeding (because of zero re-growth) and 2, 4-D plots (because of 100 % control) followed by dark plastic (5.50 cm) while maximum plant height (43.94 cm) was observed in the control treatment. The lowest density m-2of water hyacinth (0.00 plants m-2) was recorded in the hand weeding, however it was at par with dark plastic plots (1.33 plants m-2) while the highest density m-2 (28.33 m-2) was recorded in the control plots. Similarly, minimum fresh weight (0.00 kg m-2) was recorded in the hand weeding, yet it was statically similar with that of dark plastic treatment (1.29 kg m-2), while maximum (7.22) fresh weight was recorded in the control plots. There were zero re-sprouts in the hand weeding and dark plastic plots followed by 2,4-D (1.33 sprouts/ramets m-2) as compared to control (13.00 ramets m-2). Water hyacinth mortality was (100 %) in hand weeding, followed by dark plastic, 2, 4-D and glyphosate (90 % each) while the lowest mortality (5 %) of water hyacinth was obtained in S. bicolor water extract followed by P. hysterophrous (16 %) as compared to control (0.00 %). It was concluded from the research findings that hand weeding is the most effective method for the complete eradication of water hyacinth, for small scale and it is environmental friendly but the cost and availability of labor might be a hindrance in some areas, while solarization is very technical and costly too as compared to hand weeding and chemical weed control. So, herbicides can be used for large scale economically with sufficient water hyacinth control but endanger the lives of non-target species and deteriorate the environment if not used sagaciously. Therefore integration of physical removal with the use of herbicide and ecological or cultural techniques depending on the size and severity of infestation is recommended.