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Title: Hairy nightshade presence undermining some nematode-resistant potato

Author
item Boydston, Rick
item Mojtahedi, Hassan
item Brown, Charles

Submitted to: Potato Country USA
Publication Type: Popular Publication
Publication Acceptance Date: 9/1/2007
Publication Date: 11/1/2007
Citation: Boydston, R. H. Mojtahedi, and C. Brown. 2007. Hairy nightshade presence undermining some nematode-resistant potato lines. Potato Country Pg. 15. Nov. 2007.

Interpretive Summary: Columbia root-knot nematode is a major pest of potato in the Pacific Northwest and is primarily controlled by soil fumigation. Potato breeding lines have been developed with resistance to the nematode, but in field trials some resistant lines resulted in nematode damaged tubers when late season weeds were present. Hairy nightshade is a common weed in potato production and a host of Columbia root knot nematode. Hairy nightshade growing with resistant potato lines serves as a host to the nematode, which can then move to susceptible potato tubers later in the season. Some potato lines were found to express both root and tuber resistance to the nematode while other lines expressed only root resistance. Resistant potato lines grown in the presence of hairy nightshade that express only root resistance resulted in tuber damage by Columbia root knot nematode. Resistant potato lines that express both root and tuber resistance were not damaged by the nematode even when grown in the presence of hairy nightshade. These results demonstrate how weed hosts of Columbia root knot nematode may negate the positive impact of growing resistant potatoes that lack tuber resistance and the importance of weed control on managing plant parasitic nematode populations.

Technical Abstract: Columbia root-knot nematode, Meloidogyne chitwoodi, is a major pest of potato in the Pacific Northwest and is controlled by costly soil fumigation. Potato breeding lines have been developed with resistance to the predominant race 1 (CRN-1) of M. chitwoodi. Hairy nightshade, Solanum sarrachoides, is a common weed in potato rotations in the Western USA and a host of CRN-1. Studies were conducted with two potato lines with known CRN-1 resistance (PA95B4-67 and PA99N82-4) and a CRN-1 susceptible potato cultivar, Russet Burbank each grown with and without hairy nightshade. Both resistant breeding lines demonstrated root resistance to CRN-1 and exhibited only minor tuber infection when grown in the absence of hairy nightshade. However, when resistant lines were grown in the presence of hairy nightshade, some PA95B4-67 tubers were infected, whereas PA99N82-4 expressed tuber resistance. Hairy nightshade grown with potato maintained CRN-1 populations prior to potato tuber set allowing nematodes to infect developing tubers lacking resistance. PA99N82-4 grown in the presence of CRN-1 and hairy nightshade produced tubers free of nematode damage, indicating both root and tuber resistance to CRN-1. Russet Burbank tubers were nematode damaged regardless of hairy nightshade presence. These results demonstrate how weed hosts of CRN-1 may negate the positive impact of growing CRN-1 resistant potatoes that lack tuber resistance and the importance of weed control on managing plant parasitic nematode populations.