Submitted to: Potato Grower
Publication Type: Popular Publication
Publication Acceptance Date: 12/1/2002
Publication Date: 1/1/2003
Citation: BOYDSTON, R.A., MOJTAHEDI, H., THOMAS, P.E., CROSSLIN, J.M. ROTATIONAL CROPS HOLD ANSWER FOR CONTROL OF CORKY RINGSPOT. IDAHO POTATO GROWER MAGAZINE, P. 60-63. 2003.
Interpretive Summary: Corky ringspot (CRS) disease threatens over 5,000 acres of potatoes in Washington State. CRS causes necrotic arcs, rings, or spots in potato tubers, which can result in crop rejection. CRS has increased substantially in the Columbia Basin since first reported in Washington State in 1976. CRS is caused by tobacco rattle virus (TRV) and is transmitted by the stubby root nematode. Currently, soil fumigation with 1,3-dichloropropene (Telone II) prior to planting potatoes is the only method available to control or suppress CRS. In greenhouse experiments, stubby root nematodes initially infected with TRV were cleansed of the virus when growing for several generations on alfalfa or Scotch spearmint. This suggests that crop rotation could be utilized as a control measure of CRS. However, the presence of weeds in alfalfa and spearmint culture may complicate this process. We have identified common weed hosts of the stubby root nematode and TRV and demonstrated that the positive effects of growing alfalfa or Scotch spearmint can be lost if selected weeds are present. Hairy, black, and cutleaf nightshade, prickly lettuce, henbit, and common chickweed were identified as hosts of both TRV and P. allius. Targeted control of these weeds may be required to successfully eliminate CRS from fields utilizing alfalfa and Scotch spearmint rotational crops.
Technical Abstract: Corky ringspot (CRS) disease has increased substantially in the Columbia Basin since first reported in Washington State in 1976. CRS causes necrotic arcs, rings, or spots in potato tubers, which can result in crop rejection. Presently, over 5,000 acres are considered problem fields in Washington State alone. CRS is caused by tobacco rattle virus (TRV) and is transmitted by the stubby root nematode, Paratrichodorus allius. Nematodes can be cleansed of TRV when feeding on plants that are not hosts of the virus. We have demonstrated in greenhouse trials that stubby root nematode that initially carried TRV are no longer able to transmit the virus to potato after growing for several generations on alfalfa or Scotch spearmint. However, hairy nightshade (Solanum sarrachoides) grown in pots with alfalfa and spearmint served as host for both TRV and the stubby root nematode and maintained the viruliferous nematode populations. Hairy, black, and cutleaf nightshade (Solanum sarrachoides, S. nigrum, S. triflorum), prickly lettuce (Lactuca serriola), henbit (Lamium amplexicaule), and common chickweed (Stellaria media) were found to be hosts of both TRV and P. allius.