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Evaluation of potential trap crops for management of root-knot nematode on carrots

Becky Westerdahl: University of California, Davis

<div>In trap cropping, a host is planted and larvae of a sedentary parasitic nematode such as root-knot are induced to enter and establish a feeding site. Once this has occurred, and the female begins to mature, she is unable to leave the root. The plants are then destroyed before egg laying by nematodes is initiated, trapping nematodes within the root. A field trial was conducted in a field with an established population of root-knot nematode (<em>Meloidogyne javanica)</em>. There were 20-treatments, consisting of five replicates in a randomized complete block design. Five trap crops (carrots, beans, sugarbeets, tomatoes, sesame), plus 1,3-D (Telone II) as a chemical standard, and a wet fallow treatment to germinate weeds were tested. Trap crops were destroyed at three weeks after planting either by tillage, application of glyphosate (Roundup), or both; followed by planting of carrots. Dry fallow+1,3-D+tillage, Sesame+tillage, and Carrot+tillage provided an increase in the percent marketable carrots based on either number of carrots or weight of carrots compared to the untreated (<em>P=0.05</em>). At <em>P=0.05</em>, the following 11 treatments had fewer root-knot nematode juveniles in soil at harvest than the untreated control: Dry fallow+1,3-D+tillage, Wet fallow+Glyphosate, Sesame+Glyphosate+tillage, Carrot+tillage, Carrot+Glyphosate, Carrot+Glyphosate+tillage, Beans+Glyphosate, Sugarbeet+Glyphosate, Sugarbeet +Glyphosate+tillage, Tomatoes+Glyphosate, and Tomatoes+Glyphosate+tillage.</div>