A composition that contains at least citrus oil, pine oil, and salt water is effective in mitigating or eliminating a detrimental microbial, in one example, a gram-negative bacteria disease in plants. This mixture is effective against citrus greening and other gram-negative bacteria diseases. A mixture containing at least the foregoing components can be used as a root and/or a foliar treatment by diluting a concentrated mixture of the composition and spraying it on the leaves of a diseased plant or one that is prone to disease. Similarly, the combined composition can be used as a root drench or in an irrigation system to treat a diseased plant. Additional active components in a composition as disclosed herein may optionally include a surfactant (especially in a foliar application) and a growth stimulant (especially in a root drench or irrigation application).
