Abstract: New 2-phenyl-5,6-dihydro-4-pyrone derivatives and herbicidal compositions in which they are present.They correspond to the general formula: ##STR1## in which: R.sub.1 and R.sub.2, which are identical or different, represent a hydrogen atom or an alkyl radical (C.sub.1 -C.sub.4), or together form an alkylene chain (C.sub.2 -C.sub.6), R.sub.3 represents an alkyl radical (C.sub.1 -C.sub.4), an alkenyl radical (C.sub.2 -C.sub.4), an alkynyl radical (C.sub.2 -C.sub.4), a halogenoalkyl radical (C.sub.1 -C.sub.4) or an alkoxyalkyl radical (C.sub.3 -C.sub.5), Y represents a halogen atom, an alkyl radical (C.sub.1 -C.sub.4) or an alkoxy radical (C.sub.1 -C.sub.4), and n represents an integer which can be equal to 1, 2 or 3, with the proviso that, when n is equal to 2 or 3, the radicals Y can be identical or different.These compounds can be used for selectively destroying weeds in crops such as sunflower, cotton, soft wheat, rice, soya bean, groundnut, bean and tomato plant.

Abstract: Selective herbicides useful for the destruction of weeds in crops such as wheat, maize (corn), rice, cotton, groundnuts and soya, correspond to the following formula: ##STR1## in which R.sub.1 is an alkyl of 2-4 carbons, preferably isopropyl, R.sub.2 is an alkyl of 1-4 carbons, preferably methyl, and X is halogen, preferably chloro or fluoro.