Effect of Cultivars and Insecticides on Sitonid Weevil, Sitona Crinitus (Coleoptera: Curculionidae), and on Yield, Yield Components and Nodulation of Lentil (Lens Culinaris)

Abstract

An experiment was conducted during 2001 and 2002 to determine the effectiveness of different insecticides against sitonid weevil [Sitona crinitus (Herbst.)] (Coleoptera : Curculionidae) on 2 cultivars ('Sazak 91' and 'Yerli Kirmizi') of lentil (Lens culinaris Medikus). Yield, yield components and number of nodules fed by larvae were compared between the 2 cultivars as well as among insecticide treatments. Insecticides applied were chlorpyriphos (720 g ai/ha), malathion (1 300 g ai/ha) and a systemic insecticide, oxydemeton methyl (265 g ai/ha). Application of oxydemeton methyl decreased the damage on nodules by 52.6 and 41.2% in 2001 and 2002, respectively, resulting in seed yield increase (729 and 1 461.6 kg/ha in 2001 and 2002), biological yield (1 825.5 kg/ha and 3 521.6 kg/ha), pods/plant (23.8 and 25.7), 1 000-seed weight (47.7 and 48.4 g), plant height (26.1 cm and 30.0 cm), branches/plant (7.3 and 8.9), root dry weight/plant (0.136 g and 0.106 g) and shoot dry weight/plant (0.859 g and 1.056 g) over the control treatment. 'Yerli Kirmizi' cultivar showed less nodules fed (0:8 and 1.9 respectively) by the sitonid pest and gave higher seed yield (712.6 and 1 393.3 kg/ha than 'Sazak 91 (537.4 and 1 301.3 kg/ha) in 2001 and 2002 respectively.