the invention provides , improved herbicide compositions , methods of making the compositions and methods of controlling plant growth . the subject invention relates to combining fatty acid based and other herbicides with succinic acid , succinic acid derivatives and other additives such as those having essentially no herbicidal activity to increase the activity of the herbicide and provide methods of controlling plant growth by applying a combination of a herbicidal fatty acid with succinic acid and / or succinic acid derivative chemicals and / or other additives . in addition to the use of succinic acid , combining other krebs cycle acids with herbicides can also provide beneficial effects . concentrations of herbicides and additives applied to plants in accordance with the invention can include compositions involving 0 . 1 to 30 % herbicide , preferably 0 . 5 to 15 % herbicide and additive and more preferably 1 - 8 % herbicide . the ratio of herbicide , such as fatty acid herbicide to activity enhancing additives can be from 1 : 10 to 20 : 1 , preferably 1 : 1 to 20 : 1 , most preferably 1 : 1 to 5 : 1 .