Buying Harpin Protein: Online Sources for Plant Defense Activator

Harpin protein (originally marketed as Messenger®) is available from online retailers. Search "harpin protein" or "plant defense activator" for current suppliers.

What It Does

Harpin triggers systemic acquired resistance (SAR) in plants, enhancing natural defenses against pathogens and some insects. It's not a pesticide—it's a plant health stimulant.

Follow label rates and timing for vegetable garden applications.