Effects of the numbers of foliar insecticide applications on the production of the oilseed watermelon citrullus lanatus

Abstract

Citrullus lanatus is a creeping annual vine species belong to Cucurbitaceae. This plant is cultivated for its oleaginous seeds that are important in the social and cultural life of several peoples in Africa. Thus to improve its production field studies were conducted during two cropping seasons of 2007 to define an economically beneficial foliar insecticide application frequency to manage insect pests on the oleaginous C. lanatus in a woodland savannah zone of Côte d’Ivoire. Zero (control) to four sprays of a foliar carbamate-based insecticide (Cypercal EC 50) were  applied at four plant growth stages (seedling emergence, stem creeping, male flowering, and female flowering) in a completely randomised block design experiment. Four beetles and one ladybird species were identified as the most damaging insect pests on the target crop. Seed yield and most of the yield components analyzed increased with increasing number of sprays, the highest values being obtained with 3-4 sprays, according to the growing season. Between seasons variations were noted for the seed yield and all the yield components, and attributed to the negative influence of low temperature and heavy rainfalls occurring during the second growing season (18 July to 16 December 2007).

Keywords. Foliar insecticide, Carbamate, Citrullus lanatus, Cucurbitaceae, Yield, pest insects, beetles, ladybird.