Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2001
Publication Date: 2/1/2002
Citation: BOYDSTON, R.A., THOMAS, P.E., MOJTAHEDI, H., SANTO, G.S., CROSSLIN, J.M. THE ROLE OF WEEDS IN CORKY RINGSPOT DISEASE PERSISTENCE IN CROP ROTATIONS. WEED SCIENCE SOCIETY OF AMERICA ABSTRACTS, VOL. 42:59, #208. 2002.
Interpretive Summary: Corky ringspot (CRS) disease has increased substantially in soils of the Columbia Basin of Washington in recent years, and more than 5,000 acres are now contaminated. CRS disease is caused by tobacco rattle virus (TRV) and transmitted by Paratrichodorus allius nematodes in the Columbia Basin. The disease is characterized by arcs, concentric rings or diffuse extensive browning of tuber flesh that later dries into cork-like tissue, making the affected crop unsaleable. Presently, the disease is controlled by Telone II fumigant (25 gal/A), which costs about $300/A. Several standard rotation crops, such as, wheat and corn, are hosts of both the nematode vector and the virus. We have demonstrated in greenhouse experiments that TRV can be eliminated from soils by growing weed-free alfalfa or Scotch spearmint. Although these crops are good hosts of the nematode vector, the nematode cannot acquire the virus from them. P. allius molts four times in nits life cycle, and loses its virus load after each molt. Thus, it must reacquire TRV from an infected host plant before it become viruliferous again. Weeds in alfalfa and spearmint may serve as hosts for TRV and the nematode vector and may allow the TRV and nematode vector to persist in these crops. This research identified several weed species that are hosts of the virus and the nematode vector. These weeds when present in alfalfa or spearmint may nullify the positive effects of cleansing the nematode of TRV while growing alfalfa or spearmint.
Technical Abstract: Corky ringspot disease (CRS) in potato is caused by tobacco rattle virus (TRV). This virus is transmitted by the stubby root nematode (Paratrichodorus allius) in the Pacific Northwest potato producing regions. Although rotation crops such as alfalfa and Scotch spearmint (Mentha cardiaca Baker) are good hosts of P. allius, the nematode vector cannot acquire the virus from these crops. Viruliferous P. allius shed some of the virus with each molt during their life cycle and eventually the population is cleansed after several generations on alfalfa or Scotch spearmint in greenhouse trials. However, weeds in these rotation crops may serve as hosts for TRV and furthermore, the virus may spread in the seeds of some weed species. This research determined the host status of over thirty common weed species for TRV and P. allius. Canada thistle (Cirsium arvense), black nightshade (Solanum nigrum), hairy nightshade (Solanum sarrachoides), downy brome (Bromus tectorum), prickly lettuce (Lactuca serriola), henbit (Lamium amplexicaule), common chickweed (Stellaria media), and kochia (Kochia scoparia) were found to be hosts of both TRV and P. allius. In greenhouse trials, and prickly lettuce grown alone or in pots with Scotch spearmint and henbit grown alone were able to acquire TRV from viruliferous P. allius. P. allius isolated from these pots was able to transmit TRV to a susceptible host, Samsun NN tobacco. The presence of weeds that serve as hosts of both TRV and P. allius may nullify the positive effects of growing alfalfa or Scotch spearmint for CRS control. Targeted control efforts on these weeds may be required to successfully eliminate CRS from fields using alfalfa and Scotch spearmint rotational crops.