The present invention provides compositions and methods for treating, inhibiting or preventing the developing of a plant pathogenic disease. The compositions comprise volatile organic compounds effective to inhibit the growth of, or kill pathogenic microbes, including Ganoderma boninense. Invention compositions are especially useful in preventing and treating basal stem rot in the oil palm, and can be applied in the vicinity of the plant or used to sterilize the plant growth medium prior to or concurrent with plant growth therein.