Method of controlling undesired plant growth in rice

Details Method of controlling undesired plant growth in rice Method of controlling undesired plant growth in rice

1998-05-21

2000-01-25

Clardy, S. Mark

Plant protecting and regulating compositions

Plant growth regulating compositions

Organic active compound containing

504214, A01N 4354, A01N 4366

Patent

active

060178523

DESCRIPTION:

BRIEF SUMMARY
The invention is in the area of crop protection, in particular of the use of crop protection agents against monocotyledonous and dicotyledonous weeds in plant crops.
U.S. Pat. No. 4,369,058, U.S. Pat. No. 4,453,971 and U.S. Pat. No. 4,225,337 disclose N-acylated 2-aminophenylsulfonylureas, which are described as agents for controlling a wide range of mono- and dicotyledonous weeds. The sulfonylureas described are classified as herbicides having a wide activity against undesired plant growth at an application rate between 0.1 and 20 kg of active ingredient per hectare (kg of a.i./ha), preferably between 0.2 kg of a.i./ha and 10 kg of a.i./ha. According to the tests described in these publications, the compounds which were examined frequently do not have sufficient selectivity in crops of useful plants, i.e. the compounds cause considerable damage to the useful plants or have little if any herbicidal activity against harmful plants. According to the tests which have been described, the herbicidally active compounds in particular also cause considerable damage to the rice plants in rice crops.
Surprisingly, it has now been found that certain sulfonylurea herbicides have excellent selectivity in rice, and a pronounced activity against harmful plants which typically occur in rice crops is surprisingly retained even at low dosages of active compound. In particular perennial weeds encountered in the cultivation of rice which are often difficult to control, for example Sagittaria spec., Cyperus serotinus, Scirpus maritimus, Eleocharis spec. and Scirpus juncoides, and a wide range of annual weeds is controlled effectively. The sulfonylurea herbicides in question are therefore particularly suitable for controlling harmful plants in rice crops.
The present invention thus provides a method of controlling harmful plants in rice crops, which comprises applying one or more compounds of the formula (I) or salts thereof ##STR1## where R.sup.1 is an acyl radical from the group CO--R.sup.2, CS--R.sup.2, CO--OR.sup.3, CS--OR.sup.3, CO--SR.sup.4, CS--SR.sup.4, CO--NR.sup.5 R.sup.6 and CS--NR.sup.5 R.sup.6, (C.sub.3 -C.sub.6)cycloalkyl-(C.sub.1 -C.sub.4)alkyl, (C.sub.2 -C.sub.6)alkenyl or (C.sub.2 -C.sub.6)alkynyl, where each of the 5 last-mentioned radicals is unsubstituted or substituted by one or more radicals from the group halogen, (C.sub.1 -C.sub.4)alkoxy, (C.sub.1 -C.sub.4)haloalkoxy, (C.sub.1 -C.sub.4)alkylthio, (C.sub.1 -C.sub.4)haloalkylthio, CN, NH.sub.2, mono- and di((C.sub.1 -C.sub.4)alkylamino and, in the case of cyclic radicals, also by (C.sub.1 -C.sub.4)alkyl and (C.sub.1 -C.sub.4)haloalkyl, R.sup.2, except for H, R.sup.3, group of the radicals which are possible for R.sup.2, or the group 6-membered saturated or unsaturated heterocyclic radical which is bonded at the nitrogen atom, which, in addition to the nitrogen atom, contains no further hetero ring atom or further hetero ring atoms, preferably contains no or 1 or 2 hetero ring atoms from the group N, O and S, and which is unsubstituted or substituted by one or more radicals from the group (C.sub.1 -C.sub.4)alkyl, (C.sub.1 -C.sub.4)haloalkyl, halogen, (C.sub.1 -C.sub.4)alkoxy and (C.sub.1 -C.sub.4)haloalkoxy, (C.sub.1 -C.sub.6)alkoxy, (C.sub.1 -C.sub.6)alkylthio, where each of the three last-mentioned radicals is unsubstituted or substituted by one or more radicals from the group halogen, (C.sub.1 -C.sub.4)alkoxy and (C.sub.1 -C.sub.4)alkylthio, or is (C.sub.3 -C.sub.6)cycloalkyl, (C.sub.3 -C.sub.6)alkenyl, (C.sub.3 -C.sub.6)alkynyl, (C.sub.3 -C.sub.6)alkenyloxy or (C.sub.3 -C.sub.6)alkynyloxy and plants or their seeds, in an effective amount of from 0.0001 to 0.5 kg of a.i./ha, preferably 0.001 to 0.2 kg of a.i./ha, in particular 0.005 to 0.12 kg of a.i./ha.
Of particular interest are methods according to the invention using compounds of the formula (I) or salts thereof where CO--SR.sup.4, CS--SR.sup.4, CO--NR.sup.5 R.sup.6 and CS--NR.sup.5 R.sup.6, preferably CO--R.sup.2, CO--OR.sup.3 or CO--NR.sup.5 R.sup.6, (C.sub.3 -C.sub.6)cycloalkyl-(C.sub.1 -C.sub.2)

REFERENCES:
patent: 4369058 (1983-01-01), Levitt
patent: 4551531 (1985-11-01), Meyer et al.
patent: 4632695 (1986-12-01), Schurter et al.
patent: 4664695 (1987-05-01), Schurter et al.

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