Understanding the ecology of weeds is central to their effective management. Agriculture weeds cost millions of dollars each year in lost crops and prevention/treatment.
Herbicides have allowed us to continue to produce crops as demand soars, and when used safely and responsibly can be game changers. Herbicides are also expensive chemicals that need to be properly handled and applied.
To help reduce cost and to promote more organic and sustainable weed management, there are alternatives for growers that leverage our knowledge of weed ecology. One of our strongest tools to reduce weed pressure is to incorporate crop rotations. This is a long term strategy with many benefits, too many to cover in one post, so here we will look at weed suppression.
Weeds can broadly be broken down into a few categories: annual, perennial, biennial. Annuals can germinate in the early spring or in the fall. Spring germinating annuals usually set seed by the fall while fall germinating annuals usually over winter and set seed in the late spring/early summer. Perennials grow year round, usually dropping seed in the fall. Biennials usually require 2 years to grow and incorporate a dormancy period.
By knowing the germination timing and seed set timing of weeds, we can try to incorporate strategies that reduce germination or reduce the amount of seed that is shed. In the short term, this strategy can reduce in-season weeds and alleviate some competition. In the long term, this reduces the amount of seeds added to the seedbank, which cuts down on the amount of emergent weeds in subsequent years.
The use of cover crops during months where you aren’t actively growing can help suppress weeds. Timing a tillage event right after weeds have germinated or if feasible, manual removal or mowing of weeds before seed set can all help.
There are many more strategies that exploit out knowledge of weed ecology. Check back weekly for new posts on organic Cannabis tips and education!
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