The Role of Some Fungi Associated with the Nile Water Hyacinth, Eichhornia crassipes as a Biological Control Agents and Assessment of Disease Development Rate

This study was carried out in the laboratories of the Ministry of Science and Technology, Agricultural Research Directorate, to detect fungi associated with the Nile water hyacinth Eichhornia crassipes spread on the banks of the Tigris River in the Zafaraniyah area, Baghdad, Iraq, and evaluate their efficiency as biological control agents and determine the rate of disease development (r). The results obtained indicated that there were thirteen fungi associated with the Nile water hyacinth, namely: Acremonium sp. Alternaria sp., Aspergillus flavus, Aspergillus niger, Cladosporium sp., Drechslera sp., Fusarium oxysporum, Mucor sp., Penicillium sp., Pythium aphanidermatum, Rhizoctonia solani, Rhizopus sp. and Ulocladium sp. with relative occurrence of 3.45-50.7 %. The results indicated that the most common fungi were Alternaria sp., F. oxysporum and R. solani, with relative occurrence of 50.7, 34.57 and 30.50%, respectively. This is the first record for the presence of F. oxysporum on the leaves of the Nile water hyacinth in Iraq. The results also showed that the rate of disease development varied from one fungus to another when the weed was treated with fungi in the presence or absence of wounds on the leaves. The fungus Alternaria sp. was the most effective in both treatments. The highest rate of disease development was 0.650, 21-28 days after leaf wounding treatment, and 0.170, 21-28 days after the non-wounded leaf treatment. Keywords: Biocontrol, water hyacinth, fungi.