Foliar application of four herbicides (15ppm each), resulted in obvious reductions in stomatal conductance in the leaves of cotton. Percentage reductions (compared to controls) amounted to 13, 5, 18 and 33 with 2, 4-D, KCIO₃ , goal and stomp respectively. Turgor pressure followed a similar trend, and percentage decrements (compared to controls) were 23, 6, 20 and 35 with 2, 4-D, KCIO₃ , goal and stomp respectively. The negative effect of these herbicides on stomatal conductance and turgor pressure  could be attributed to the documented drastic effects of many herbicides on biochemical and physiological processes in non target plants.