Greenhouse studies were conducted to determine the efficacy of two granular systemic insecticides, acephate (Pinpoint 15G) and imidacloprid (Marathon 1G), against western flower thrips (Frankliniella occidentalis Pergande) on Transvaal daisy (Gerbera jamesonii H. Bolus ex. Hook. f). These studies were arranged in a randomized complete-block design with four blocks and four treatments per block. Two rates of acephate (0.75 g/16.5-cm pot and 1.0 g/16.5-cm pot) and one rate of imidacloprid (1.3 g/16.5-cm pot) were used in two studies. Plants were artificially inoculated with five adult western flower thrips at the prebloom stage. Plants were evaluated each week for flower quality (1 = complete injury or flower distortion to 5 = no injury), thrips density per flower, and number of plants flowering in each plot. Both studies showed that the acephate treated plants had the best flower quality, lowest numbers of thrips, and greatest number of plants flowering compared to imidacloprid and the check. These studies demonstrate that granulated acephate exhibits some activity in flower tissue and may assist growers in managing western flower thrips in floricultural crops.
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