ARS | Publication request: Weed hosts Globodera pallida from Idaho

Submitted to: Plant Disease
Publication Type: Research Notes
Publication Acceptance Date: March 16, 2010
Publication Date: June 16, 2010
Citation: Boydston, R.A., Mojtahedi, H., Bates, C., Zemetra, R., Brown, C.R., Anderson, T.L. 2010. Weed hosts Globodera pallida from Idaho. Plant Disease. 94(7):918

Technical Abstract: The potato cyst nematode, Globodera pallida (PCN), a restricted pest in the USA, was first reported in Bingham and Bonneville counties of Idaho in 2006. The US government and Idaho State Department of Agriculture hope to eradicate it from infested fields. Eradicating PCN will require depriving the nematodes of their hosts over a protracted time period. Functional eradication might be achieved using relatively high, proven to be efficacious dosages of soil fumigants. The presence of host weeds of PCN can play a significant role in success of the eradication program. To determine the host status of common weeds found in potato fields of the Pacific Northwest, host suitability tests were conducted in a secured greenhouse located at the University of Idaho at Moscow. Reproduction of PCN on nine weeds including hairy nightshade (Solanum physalifolium formerly S. sarrachoides) and cutleaf nightshade (S. triflorum) (biotypes from ID and WA), black nightshade (S. nigrum) (WA biotype), bittersweet nightshade (S. dulcamara) (ID biotype), redroot pigweed (Amaranthus retroflexus), kochia (Kochia scoparia), and common lambsquarters (Chenopodium album) were compared to reproduction on Desiree, Russet Burbank (known hosts), and Santé (poor host) potatoes (S. tuberosum). Plants were grown in 10-cm-d clay pots containing sandy loam soil previously fumigated with methyl bromide, and inoculated with 10-150 cysts that were either collected from infested fields, or raised in the secured greenhouse (ample diapause period elapsed). Treatments were replicated five times and each trial lasted 3 months. Cysts were extracted from soil using a Fenwick can, and the reproductive factor (RF = final cyst count ÷ initial inoculum) was determined. While both biotypes of hairy nightshade were suitable hosts of PCN (161-668 ÷ 150; RF > 1), cutleaf biotypes, black, and bittersweet nightshades were poor hosts (1-108 ÷ 150; RF < 1). Russet Burbank (77 ÷ 40; RF = 1.9), Desiree (21-119 ÷ 75; RF > 1) proved to be suitable hosts, and Santé (1-20 ÷ 150; RF < 1) a poor host of Idaho PCN. Although some cysts were recovered from pots containing the remaining weed species, they may have been part of the original inoculum. The significance of nightshade species (whether suitable or poor hosts) in eradication of potato cyst nematode from infested fields cannot be overemphasized.