Abstract
3-Phenoxypyridazines and related compounds were evaluated their pre-emergence activities. Of these, 3-phenoxy-, 3-(2-methylphenoxy)-, and 3-(2-ethylphenoxy)-pyridazines (III, IV and VII) showed powerful effects on barnyardgrass and spikerush, whereas they gave no injury on rice plants. Furthermore, susceptibility of various kinds of cultivated plants as well as of weeds to III and IV were examined. Growth regulating activity of III was compared with that of maleic hydrazide.