Eliminating Tobacco Rattle Virus from Viruliferous Paratrichodorus allius and Establishing a New Virus-Vector Combination.

A reliable method to eliminate tobacco rattle virus (TRV) from viruliferous Paratrichodorus allius populations was developed. This virus is vectored by P. allius in the Pacific Northwest and causes corky ringspot disease (CRS) of potato. The viruliferous nematodes that were reared on 'Vernema' alfalfa or '770' scotch spearmint for at least 3 months did not transmit TRV to 'Samsun NN' tobacco, a suitable indicator plant, and did not cause CRS symptoms on 'Russet Norkotah' tubers. A new isolate of TRV was introduced into a nonviruliferous population of P. allius. First, tobacco plants were inoculated with a field population of P. allius that transmitted an isolate of TRV that caused severe symptoms on potato. The tobacco roots were then washed free from soil and dipped in 0.525% sodium hypochlorite to remove the initial nematode inoculum. After the disinfected tobacco plants recovered and began to grow, the virus-free population of P. allius was introduced around the root system to acquire the new virus isolate from tobacco roots. The newly established virus-vector combination caused CRS symptoms on 'Russet Norkotah' that were characteristic of the more virulent virus isolate, indicating that the virus-free P. allius population had reacquired virus.