Synergistic herbicide combinations and method of application

A synergistic herbicidal composition comprising a mixture of: (a) a herbicidally effective amount of 2-(2-chloro-4-methanesulfonylbenzoyl)-1,3-cyclohexanedione; and (b) a herbicidally effective amount of a compound selected from the group consisting of 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine, 3-amino-2,5-dichlorobenzoic acid, and 2-chloro-N-isopropylacetanilide, and mixtures thereof; at a weight ratio of (a) to (b) of from about 0.1:1 to about 20:1.

BACKGROUND OF THE INVENTION 
The protection of crops from weeds and other vegetation which inhibit crop 
growth is a constantly recurring problem in agriculture. To help combat 
this problem researchers in the field of synthetic chemistry have produced 
an extensive variety of chemicals and chemical formulations effective in 
the control of such unwanted growth. Chemical herbicides of many types 
have been disclosed in the literature and a large number are in commercial 
use. 
In some cases, active herbicides have been shown to be more effective in 
combination than when applied individually. The result is often termed 
"synergism" since the combination demonstrates a potency or activity level 
exceeding that which it would be expected to have, based on a knowledge of 
the individual potencies of the components. The present invention resides 
in the discovery that certain cyclohexanediones and other chemical 
compounds already known individually for their herbicidal potency, display 
this synergism when applied in combination. 
THE PRIOR ART 
The compounds which can be combined to form the synergistic herbicidal 
compositions of this invention are already known in the art as herbicides. 
One such compound is 
2-(2-chloro-4-methanesulfonylbenzoy)-1,3-cyclohexanedione. This compound 
is disclosed in European Patent Publication No. 137,963, published 4-4-85. 
It is also disclosed and claimed in U.S. application Ser. No. 634,408. 
Another of the compounds used in the synergistic compositions of the 
invention is 2-chloro-4-(ethylamino)-6-(isopropylamino)-striazine, 
commonly know as Atrazine. Still another compound used in the synergistic 
hericidal composition of this invention is 3-amino-2,5-dichlorobenzoic 
acid, commonly known as Chloramben, described and claimed in U.S. Pat. 
Nos. 3,014,063 and 3,174,842. Yet another compound used in the synergistic 
compositions of this invention is 2-chloro-4-N-isopropylacetanilide, 
commonly known as Propachor.