Determination of residue levels of natural pyrethrin (pyagro 4% ec) and pre-harvest interval (phi) on tea in Kenya

Kenya is a one of the major tea-producers of tea in the world .The tea is grown in the highland areas with adequate rainfall and low temperatures. The main tea-growing area is in the Kenyan Highlands, west and east of the Rift Valley, at altitudes between 1800M m. a. s. l. and 2400M m. a. s. l. Tea is a major foreign exchange earner, and the main source for 17 to 20 percent of Kenya's total export revenue. Pests are responsible for yield losses up to 30% in tea world wide. In Kenya pests especially mite pests cause appreciable losses especially during dry period. The most common pests include mite pests, weevils, aphids and mosquito bugs (Helopeltis sp.). A number of pesticides have been tested for their efficacy in controlling these pests. Any chemical used to control pests in tea should not contaminate the final product the made tea. Any residues in the product should comply with international standards on the Maximum residue Limits (MRLs). The current study was carried out in order to establish residue levels of Pyrethrins in fresh tea leaves, black tea and brewed tea after foliar application. The study monitored the decline of pesticide residues under normal harvest time intervals and also evaluated the effect of tea manufacturing process on the Pyrethrin residue levels in black tea. Tea samples were collected by picking two leaves and a bud at various pre-harvest intervals after application of the pesticide Pyagro 4%EC at maximum proposed application rates. Results show that the levels of the pesticide residues decreased with increase in the pre-harvest interval in days. The results reveal that residues found in samples collected on the first day after application contain the highest residue levels and those collected fourteen days after application contained the lowest residue levels. The processing and brewing of tea appear to lower the residues of Pyrethrins (Pyagro) significantly. The residue levels from the study are lower than the maximum residue levels (MRLs) allowed within the European Union. Therefore, if Pyagro 4% EC pesticide is used according to the established pattern for control of tea pests it will pose no risk to the consumers of tea.