Risk factors

Sandy and loamy light soils, high soil content in organic matter and soil temperature around 15°C - 20°C favour the activity of the nematodes but TRV and its vector have been found in very diverse types of soil.

TRV may be retained in trichodorid nematods for many months but the virus may also survive in many weeds or plant seeds.

The potato is not a good host plant and the level of susceptibility of the cultivar is another important factor in the occurrence and severity of the spraing symptoms. However, although some potato cultivars are resistant to infection, others are merely tolerant, i.e. they may be systemically infected but produce few or no tuber symptoms.

• Host plants

TRV has one of the widest known host range of any plant virus. More than 400 species in more than 50 dicotyledonous and monocotyledonous families can be infected experimentally; in many cases the infection does not become systemic.

Host range includes many cultivated plants, including ornementals (bulbs such as tulip, narcissus, and hyacinth and also asters or hydrangeas), potato, beet, lettuce, spinach, artichoke and tobacco.

TRV can infect many plants from the Gramineae, for example Poa, and many weed species from various genera (Amaranthus, Capsella, Merculiaris, Polygonum, Solanum, Stellaria, Vicia,..).