This invention relates to agricultural compositions, particularly pesticidal compositions which find particular use as a fungicide or herbicide composition. The pesticidal composition can include one or more fatty acids and one or more organic acids different from the fatty acid. The organic acid can but need not exhibit any fungicidal activity; however, when combined with a fatty acid, the organic acid functions as a potent synergist for the fatty acid as a fungicide. Additionally, the pesticidal composition can include other components such as emulsifiers, adjuvants, surfactants and diluents. The pesticidal composition significantly reduces or prevents the fungal infection of cash crops including vegetables, fruits, berries, seeds, grains and at higher application rates, can also be used as a herbicide and/or harvest aid or desiccant for harvested crops such as potatoes. The addition of an emulsifier further enhances the herbicidal properties of the compositions.