by Patty A. Gray, Garden Program Director
There is a fascinating body of cancer research that, oddly enough, has relevance for the health of the garden (see Siddhartha Mukherjee’s article “Cancer’s Invasion Equation” in the Sept. 11, 2017 issue of The New Yorker).
Research increasingly demonstrates that cancer cells are always present in our bodies to some degree; they are never completely eradicated. But they also may never manifest in harmful ways if the proper environmental conditions to suppress them are maintained – the health of the body’s immune system. One way to treat malignant cancer is to use chemotherapy, which knocks back cancer cells – but it is also toxic to the whole body, damaging the very immune system that fights the cancer cells.
As I was reading about this, I was reminded of weeds in the garden (not that it takes much to remind me of the weeds in the Robb Garden – I have a much more intimate relationship with them than I would care to admit). Weeds and their reproductive parts – seeds, rhizomes, etc. – are always present in the garden. We pull and pull and pull weeds, but there are always more popping up behind the ones we got rid of. Of course, we could treat the weeds with a systemic herbicide, but that would be like treating a cancer with chemotherapy: it would knock back the offending weeds, but it would also damage, even kill, the plants that we want in the garden (I won’t even go into the damage that the herbicide residues could do to the bodies of the humans who ingest them).
Both approaches – chemotherapy on humans, herbicides on plants – address an invading organism by making the entire environment toxic. And yet, neither method will ever completely eradicate the presence of the invaders. Every Gardener knows that weed seeds are always present, perhaps unseen, but nevertheless lying dormant beneath the soil surface.
The agricultural methods we’ve come to take for granted involve mechanically tilling the soil – which brings those weed seeds to the surface where they delight in the sunshine, water, and ideal growing conditions created for them – and then spraying chemicals to kill the weeds. When the chemicals threaten to damage the desired crops, the crops are genetically modified to resist that damage. Rather than working with the natural conditions of soil and plants, we’ve worked against them.
There is another way, of course, and that is to accept the perpetual presence of weeds, but to encourage the environmental conditions that create balance and prevent weeds from taking over. Minimal tilling of the soil (which not only keeps weed seeds way down under but also preserves the structure of the soil), keeping the soil covered at all times with green plants (crops or ground covers), and pulling weeds to weaken their photosynthesis mechanism – these are examples of techniques that work. But it requires one to feel comfortable with complexity – to be willing to figure out how all the parts of the intricate environmental system work together, and to work with that system and not against it.