The side effect and behaviour of certain insecticides in cotton plants

Abstract

Cotton plants variety Giza 75 &70 were planted in the ex­ perimental farm of Zarzora Research Station, Behira Governorate in the growing season of 1993 &1994. Different schedules were planned for cotton application with different insecticides according to the recommendations of the Ministry of Agriculture of Egypt to control cotton leafworms and bollworms. The results showed that all insecticides used during the two seasons have no significant effect on the stem hieght, opened, closed, spoiled, total number of bolls, boll size and weight except that of cyanophos and methomyl which significantly increased plant height and opened bolls, respectively. Furthermore, esfenvalerate alone or with cyanophos and es-fenvalerate/thiodicarb treatments gave the highest percent of boll opening than other treatments at the end of 1994 season ( last boll sample). All treatments of 1993 growing season (cotton Giza 70) revealed a significant reduction in cotton yield but it increased insignificantly with all treatments of 1994 growing season (cotton Giza 75). Lint properties showed insignificant changes by insecticides treatments of the cotton. All insecticides alone or in sequence programs showed an increase in the endogenous plant growth hormones (Auxins, Gibberellins and Cytokinins) of bolls or leaves ( except es­ fenvalerate and cyanophos/es-fenvalerate treatments which decreased auxins leaves content), total soluble sugar, chlorophyll and carotenoids of treated leaves. In addition, all insecticides