Abstract: Formulations containing aqueous phosphonic acid plant growth regulator dispersed in oil are disclosed that are stable and particularly suited for use with ultra-low volume spray apparatus.

Abstract: Substituted pyrimidine compounds particularly useful as selective post-emergent herbicides are described for inhibiting the growth of and killing undesirable plants and weeds. The compounds hereof include 2,4-substituted pyrimidine-5-carboxylates having the general formula ##STR1## wherein X, Y and R represent specific types and classes of substituent groups. Especially preferred compounds in accordance with the invention include octyl 2,4-dichloropyrimidine-5-carboxylate, benzyl 2,4-dichloropyrimidine-5-carboxylate, allyl 2,4-dichloropyrimidine-5-carboxylate, ethyl 4-chloro-2-mercaptopyrimidine-5-carboxylate, butyl 2-chloro-4-di-n-propylaminopyrimidine-5-carboxylate. The compounds may be applied by conventional spray techniques at a dosage rate of from about 1/4 to 20 pounds per acre to good effect.