Plant Immune Systems and the Organic Garden

Posted by Jamie McIntosh Sep 2, 2009

I have to admit, until recently, when I heard the phrase “plant immune system,” I was skeptical about the notion. This sounded more like a marketing term, or some kind of anthropomorphic fantasy, along the lines of talking to plants to stimulate their growth. However, through my writing and research, I’ve learned more about the fascinating mechanisms that strengthen or weaken a plant’s ability to fight off disease pathogens. Beneficial soil microbes are just one aspect of a plant’s functioning immune system.

For example, the bacterium Bacillus subtilis produces a natural antibiotic that competes against disease-causing plant fungi. Horticultural scientists harness these kinds of symbiotic relationships to create new organic fungicides for the farmer and home gardener. Although organic gardening methods can be as simple as a floating row cover or a homemade baking soda spray, they can be surprisingly sophisticated as well.