Pesticides and cotton: effect on photosynthesis, growth, and fruiting

Field studies were conducted in 1972 and 1986 to determine the effect of selected, commercial insecticides and acaricides (pesticides) on growth, fruiting patterns, and yield of 'Acala SJ-2' cotton, Gossypium hirsutum L. There was a strong tendency in the 1972 study toward less boll retention in plots treated "season-long" with methyl parathion at all test sites, as well as a significant reduction in the weight of lint cotton at one site. In the 1986 study, four weekly applications of methyl parathion significantly reduced mesophyll conductance, boll retention, number of mature and open bolls per plant, number of first position bolls per plant on mainstem nodes 5-7, weight of lint cotton at harvest, and dry weight accumulation of fruiting forms. None of the other pesticides tested in the 1986 study, including chlordimeform, significantly increased any plant growth parameter when compared with the control