Evaluation of <i>Solanum sisymbriifolium</i> and <i>Chenopodium quinoa</i> as trap crops for <i>Globodera pallida</i> in rotation with susceptible and resistant potato

<i>Globodera pallida</i> is a quarantine pest of potato in Idaho, which is being eradicated through use of soil fumigants. Planting trap crops may be helpful for eradication efforts. <i>Globodera pallida</i> requires a hatching factor, without which eggs remain dormant for decades. Trap crops for <i>G. pallida</i> induce hatch but prevent development thereby reducing populations. Prior research suggests that quinoa (<i>Chenopodium quinoa</i>) is a nonhost which induces hatch. Several varieties of quinoa ('Biobio', 'Cherry Vanilla', 'French Vanilla', 'Kailey', 'Oro de Valle', and 'Red Head') were evaluated for <i>G. pallida</i> host status and hatching effect. All quinoa varieties under evaluation were found to be nonhosts that caused greater hatch than bare soil, but less than potato. Quinoa was further assessed as a trap crop in comparison to <i>Solanum sisymbriifolium</i>, a known highly effective trap crop for <i>G. pallida</i>. These trap crops were also investigated in rotation with resistant or susceptible potato. Results from greenhouse and field trials showed that when in rotation with the susceptible potato 'Russet Burbank', quinoa reduced <i>G. pallida</i> progeny cysts by 37 to 40%, while <i>S. sisymbriifolium</i> reduced <i>G. pallida</i> progeny cysts by 82 to nearly 100%. Rotating quinoa, <i>S. sisymbriifolium</i>, or barley to the resistant potato variety 'Innovator' resulted in a <i>G. pallida</i> reproduction factor of nearly zero or zero. As a trap crop, quinoa is not as effective as <i>S. sisymbriifolium</i> but does cause reduction of <i>G. pallida</i>. Ultimately, a resistant potato variety in rotation is also a valuable control measure.