Effects of butachlor, bensulfuron-methyl, and dimethoate on the growth, photosynthesis, and photoinhibition of the edible cyanobacterium Ge-Xian-Mi were examined in order to gain insight into the relationship between its productivity reduction and the abusive use of pesticides in the field. Severe inhibition of growth was found in the presence of four- to six-fold field concentration of butachlor and very high concentrations of bensulfuron-methyl and dimethoate. Mild stimulation of photosynthesis was observed over a limited range of low concent...