The predominant mode of spread of ToRSV is via the nematode vector Xiphinema americanum, also known as “Dagger” nematodes. Methyl bromide is often a method of choice for managing ToRSV and other nematode-borne plant viruses because it kills the nematode vectors. However, ToRSV often reappears within 3-4 years of fumigation with methyl bromide. This is because nematodes below the depth of effective fumigation survive and can reinfect new raspberry plants. In addition to incomplete success with soil fumigation, methyl bromide is scheduled to be phased out of commercial agricultural use by Jan. 1, 2005.

Alternative approaches are clearly needed to control virus-vectoring nematodes and plant-parasitic nematodes.  Integrated pest management strategy development is dependent on understanding the population dynamics and epidemiology of vector nematodes, and epidemiology of viral plant diseases.   In this study, we examined the epidemiology of ToRSV spread, population dynamics of X.  americanum, developed a cucumber bioassay to detect virus-carrying nematodes, designed and tested the effects of cover-cropping systems on nematode populations and disease transmission, and developed diagnostic tools to monitor the spread of ToRSV in field infections and in the vector nematodes.