Crop rotation has been considered a basic principle of sustainable agriculture for thousands of years. Rotation of the crop grown on a field (including a fallow period) benefits the grower and the environment by improving soil fertility and tilth, and controlling pests and weeds.
Legal outdoor cannabis growers are in a unique historical situation - they are required to grow their crop behind large fences, with costly security cameras and other infrastructure in place. The cost of complying with regulations severely limits the potential for crop rotation, with many growers planting in exactly the same location year after year.
This is not the grower's fault, but we will undoubtedly observe a buildup of cannabis pests and disease over the coming years with the following consequences:
- growers more dependent on pesticides
- diseases more resistant to those pesticides
- threats to consumer health
Making matters worse is the need to dispose of unwanted plant material near the grow-site. Compost piles can create a reservoir for disease and insects to survive over the winter. I'd encourage all growers to be very careful about sanitation and hygiene, as well as the source of any plant material that may be brought onto the farm.
Let's hope the march of progress in cannabis legalization proceeds. In the meantime we'll be working on breeding more disease resistant varieties.