The present invention relates to use of vegetable oils such as 
soybean oil as an 
adjuvant for substances having a 
fungicide, bactericide and insecticide activity in preventive or curative treatments of 
plant diseases caused by fungi, 
bacteria and insects on agricultural cultivations. In addition, the present invention relates to use of vegetable oils such as 
soybean oil as an 
adjuvant for substances having a herbicide activity in treatments for 
weed control on agricultural cultivations. Finally, the present invention relates to a 
fungicide, bactericide, insecticide or herbicide composition characterized in that it comprises: a stable water 
emulsion of vegetable oils such as 
soybean oil; and at least one substance having a 
fungicide, bactericide, insecticide or herbicide activity.