Prepare Your Plants To Perform! With Bush Doctor Manganese. You probably think you"ve covered all your bases: your NPK is on point, your pH is dialed in, and there isn"t a pest in sight. Sounds good, but did you know that plants without Manganese can suffer? This important micronutrient plays a valuable role in photosynthesis and helps plants hold their own against environmental stresses. OMRI Listed and Registered CDFA Organic Input Material.