Using seasonal tillage in combination with cover crops as a biological method to control cutworms in organic cruciferous crops

Description

A number of vegetable crops, including crucifers, suffer severe damage from cutworms in the spring. Organic growers are running out of solutions for dealing with the situation. Little is known about the ecology of cutworms in the field and about sampling techniques for these pests. Although tests on weed incidence and ploughing have been conducted in Europe and elsewhere in North America, no one has, as of yet, carried out such studies in Québec. The goal of this project is to assess the extent to which cover crop ploughing and burying practices can limit the damage cutworms inflict on vegetable crops. First, we will conduct trials to determine the best caterpillar sampling technique (pitfall traps, bait traps, refuge traps, or soil sifting) and characterize the pest’s spatial distribution before and after planting the vegetable crop. The impact in the field of these cover crop destruction methods on the black cutworm and darksided cutworm populations will then be assessed:

• fall ploughing (bare ground)
• cover crop mown in the fall and residues incorporated in the spring
• cover crop mown and partially incorporated in the fall
• cover crop mown and fully incorporated in the fall

The effect of these treatments on the abundance and spatial distribution of cutworms in cabbage plots will shed light on which practice provides the most satisfactory control of cutworms in organic vegetable production.

Objective(s)

• Determine the best sampling technique in the fields and hedgerows from among four techniques, and characterize the spatial distribution of the caterpillars before and after planting the vegetable crop.
• Assess the effect in the field of three cover crop destruction methods on both the black cutworm and darksided cutworm populations.