Survey, Biological and Chemical Control of Water Hyacinth (Eichhornia crassipes (Mart.) Solms) in White Nile State -Sudan

Abstract

This research was conducted in the White Nile State in September 2006 and April 2007, to estimate the occurrence of the water hyacinth as well as the distribution and the damage caused by two weevils, and a moth, for the water hyacinth (Eichhornia crassipes (Mart.) solms, in the White Nile. The survey covered Jebel Aullia, Elduam, Kosti, Elgabalien, Joddah and Elrenk. The study was also carried out to compare the effect of the cheavroned weevil Neochetina bruchi and the mottled weevil Neochetina eichhornaie Warner on the growth and productivity of the water hyacinth which was grown for two months in a nursery. Another study was done to evaluate the effect of two herbicides at 3 rates on the control of the water hyacinth plant. The herbicides used were 2, 4-D at the rates of (1.25, 2.5, 3.75 l/f) and glyphosate at the rates of (2.1, 4.2, 6.3 l/f). The experiments were conducted in a nursery in Kosti. Surveys showed that the distribution of water hyacinth increased towards the south, the total area of water hyacinth between kosti and Elrenk was estimated to be 61.19 feddans and 22.6 feddans a long the white Nile bank in September 2006 and April 2007 respectively. The average weight was estimated as 12 kg/m2. x Survey also indicated that the average number of adult weevils in kosti, Elgabalien and Joddah, was 2 adults and 2 larvae per plant, in Elrenk,the average was 4 adults and 2 larvae per plant, however the weevil was not found in Jebel Aulia and Elddium. The Survey showed the absence of Sameodes albiguttals in the water hyacinth population. Results were also taken from stocking water hyacinth plants with four adults and four larvae of both species separately on 6 water hyacinth plants for a period of two months. Four larvae of Neocheina eichhorniae per plant reared (feeding) separately reduced the population of hyacinth by 20% in off sets while similar number of Neochetina bruchi four larvae per plant feeding separately reduced the population of hyacinth by 40% in off shoot production. And similar number of adult males of Neocheina eichhorniae and Neochetina bruchi each reduced off shoot production by 21.42% and 42.85% respectively. The adults were found to be more efficient than the larvae. Results of the chemical control experiments indicated that the three levels of the herbicide 2,4- D in all its rates (1.25, 2.5, 3.75L/f) and the herbicide glyphosate in all its rates (2.1, 4.2, 6.3 l/f) were effective in controlling the water hyacinth ; 2.4-D gave best control in 1.25 l/f and 3.75 l/f which was 92% and 93.3% respectively 3 days after application, and gave 95%, 100%, 12 days after application at 1.25 l/f, 3.75 l/ f respectively. The herbicide glyphosate gave best control at the rate of 6.3/ l/f which was70.3%, 83.3%, 22 days, 25 days from first application respectively; the results confirmed that the herbicide 2, 4-D was more effective than glyphosate in all its rates in controlling water hyacinth.