Development of two methods to combat perennial sow thistle (Sonchus arvensis L.) and Canada thistle (Cirsium arvense) in organic field crop production

Field experiments on two large-scale farms tested the use of two types of spring fallow to suppress sow thistle and Canada thistle.  Spring fallow was followed by either buckwheat (for harvest) or a vigorous green manure crop.  The experimental results indicate that following a short spring fallow with the planting of an aggressive green manure is effective for the suppression of Canada thistle or sow thistle.