Abstract:
Improper pesticide application has resulted in high toxicity levels causing environmental risk. The objective of the study
was to determine pesticide preferences and pattern of use in farms along the shore of Lake Naivasha. Interviewer
administered questionnaires and researcher observation were used to collect data on pesticides being used and pattern
of use in 20 major horticultural farms around Lake Naivasha. Secondary data from journals, standards and materials
safety data sheets from manufacturers were also used to determine pesticide properties such as toxicity. The results
showed there were 4.3% (6) WHO class I and 14.3% (20) class II pesticides of the 141 pesticides used along the shore of
Lake Naivasha. The pattern of pesticide use in the area was moderate to high and all the farms were also using
Integrated Pest Management (IPM) to control pests. It was concluded that some pesticides in WHO class I that were
being used along the shore of Lake Naivasha (e.g. oxamyl, methomyl and fenamiphos) are very toxic to human beings
and aquatic organisms since they cause cholinesterase inhibition poisoning by inactivating the enzyme
acetylcholinesterase.
