Effects of Rainfall on Systematic Insecticides in the control of Leucoptera Meyricki in Kenya

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Wanjala, F.M.E.
Dooso B.S
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Coffee leaf miners are ubiquitous, chronic pests throughout Arabica coffee producing areas of Kenya. Although stands of young Coffea Arabica L. occasionally suffer from dense infestation by the leaf miners, Leucoptera meyricki Ghesq. and Leucoptera caffeina Washb., most damage occurs in the mature coffee plantations. The aforementioned Leucoptera spp_ attack unshaded and shaded coffee respectively. They mine the palisade layer underneath the upper leaf epidermis preferring old but discriminating against tender leaves. It is not. known how leaf selection is done by female moths which initiate infestations during oviposition. Coffee leafminers produce up to eight continuous generations per year with marked peaks about September - November_ Several factors account for outbreaks in Kenya. Infested leaves make trees unsightly with reduction of potentially photosynthetic leaf areas ( 4) . Consequently, growers employ annual insecticide sprays to minimise mining and subsequent leaf fall. Economic thresholds of 35 + moths per tree are established by activated flight count of moths that take off when canopies are vigorously disturbed (2). Foliar sprays of organophosphate insecticides have proven especially effective against leafminers (6).
Turrialba, 29 (4), pp. 311-315