Use of quinoline derivatives for protecting cultivated plants

The invention relates to the use of quinoline derivatives of formula ##STR1## wherein R.sub.1, R.sub.2 and R.sub.3 are each independently hydrogen, halogen, nitro, cyano, C.sub.1 -C.sub.4 alkyl or C.sub.1 -C.sub.3 alkoxy, PA0 R.sub.4, R.sub.5 and R.sub.6 are each independently hydrogen, halogen or C.sub.1 -C.sub.3 alkyl, PA0 A is a group selected from --CH.sub.2 --, --CH.sub.2 --CH.sub.2 -- or --CH(CH.sub.3)-- and PA0 Z is (a) cyano or amidoxime which may be acylated at the oxygen atom, or (b) a carboxyl group or a salt thereof, a mercaptocarbonyl group or a salt thereof, an esterified carboxyl group, a thiocarbonyl group, an unsubstituted or a substituted carbamoyl group, a cyclized unsubstituted or substituted derivative of a carbamoyl group, or is a carbonohydrazido group; or A and Z together are an unsubstituted or a substituted tetrafuran-2-one ring. PA0 and the acid addition salts and metal complexes thereof, for protecting cultivated plants from the harmful effects of herbicidally active derivatives of (4,5-dihydro-4-oxo-1H-imidaszol-2-yl)benzoic acid, (4,5-dihydro-4-oxo-1H-imidazo-1-2-yl)nicotinic acid and (4,5-dihydro-4-oxo-1H-imidazol-2-yl)quinolinecarboxylic acid. The above mentioned herbicidal derivatives have the formula II ##STR2## wherein R' is hydrogen, C.sub.1 -C.sub.4 alkyl, the ammonium cation or an organic ammonium cation, R.sub.1 ' is C.sub.1 -C.sub.4 alkyl, R.sub.2 ' is C.sub.1 -C.sub.4 alkyl or C.sub.3 -C.sub.6 cycloalkyl, or R.sub.1 ' and R.sub.2 ' together are C.sub.4 alkylene or C.sub.5 alkylene, M is the structural unit .dbd.CH-- or .dbd.N--, X and Y are each independently of the other hydrogen, C.sub.1 -C.sub.4 alkyl or halogen or, if M is .dbd.N--, are additionally the structural unit --C(X.sub.1).dbd.C(X.sub.2)-- C(X.sub.3).dbd.C(X.sub.4)--, wherein X.sub.1, X.sub.2, X.sub.3 and X.sub.4 are hydrogen or one or two of X.sub.1, X.sub.2, X.sub.3 and X.sub.4 are C.sub.1 -C.sub.4 alkyl and the others are hydrogen.

The present invention relates to the use of quinoline derivatives for 
protecting cultivated plants from the harmful effects of herbicidal 
derivatives of (4,5-dihydro-4-oxo-1H-imidazol-2-yl)benzoic acid, 
(4,5-dihydro-4-oxo-1H-imidazol-2-yl)nicotinic acid and 
(4,5-dihydro-4-oxo-1H-imidazol-2-yl)quinolinecarboxylic acid. 
When applying herbicides such as the imidazole derivatives referred to 
above, appreciable damage may be caused to the cultivated plants depending 
on such factors as, for example, the concentration of herbicide, the mode 
of application, the species of cultivated plant, the nature of the soil, 
and climatic conditions such as the duration of exposure to light, 
temperature and rainfall. In particular, severe injury may result when, in 
the course of crop rotation, other cultivated plants that have no or only 
insufficient resistance to the herbicides are grown after the cultivated 
plants that are resistant to the herbicides. 
It is known from published European patent specifications Nos. 86 750 and 
94 349 that quinoline derivatives can be used for protecting cultivated 
plants from the harmful effects of aggressive agrochemicals. 
Surprisingly, it has not been found that protection of cultivated plants 
from injury caused by herbicidal derivatives of 
(4,5-dihydro-4-oxo-1H-imidazol-2-yl)benzoic acid, 
(4,5-dihydro-4-oxo-1H-imidazol-2-yl)nicotinic acid and 
(4,5-dihydro-4-oxo-1H-imidazol-2yl)quinoline carboxylic acid can be 
afforded by dressing the seeds of said plants with a safener selected from 
the group of quinoline derivatives. The cited herbicides, which remain 
active in the soil for some considerable time, are preferably used in 
soybean crops, as soybean plants are sufficiently resistant to these 
herbicides. However, considerable injury is often caused to subsequent 
crops. This applies in particular to crops of cereals. By dressing the 
seeds of non-resistant cultivated plants it is possible to alternate 
soybean crops with crops of other cultivated plants without damage being 
caused by the herbicides to these subsequent crops. No loss of herbicidal 
activity against weeds and grasses results. 
Furthermore, the use of quinoline derivatives also makes possible the 
direct application of the herbicidal derivatives of 
(4,5-dihydro-4-oxo-1H-imidazol-2-yl)benzoic acid, 
(4,5-dihydro-4-oxo-1H-imidazol-2-yl)nicotinic acid and 
(4,5-dihydro-4-oxo-1H-imidazol-2-yl)quinolinecarboxylic acid in crops of 
cultivated plants that have no or only insufficient resistance to these 
herbicides.