Control and detection

• Control measures

Soil cultivation and effective weed-control throughout the rotation are ways of reducing nematode populations in the soil and thus the risk of disease. Growing cereals for several years before the potato may help to reduce the virus but not the nematodes.

Knowledge of the history of the disease in a given area or farm can be useful for crop management and the choice of potato cultivars. The most susceptible cultivars should be planted in fields with no record of TRV whereas resistant or tolerant cultivars should be planted in infected fields.

Soil treatments used to deal with other types of nematode are effective in reducing the nematode populations and therefore the dissemination of the Tobacco rattle virus (TRV). However, they are expensive and harmful to the users and the environment.

• Detection

Whilst there are numerous Elisa TRV detection kits, they are not reliable on potatoes because, in both tubers and foliage, TRV is often in the form of free nucleic acid and is thus undetectable with serology. A number of molecular methods have been described but none of them are fully reliable.

Diagnosis of the TRV involves (when it is feasible) several operations:

a) soil testing with the identification of Trichodorus and Paratrichodorus nematodes;

b) baiting the virus in the soil by means of baiting plants such as Physalis floridana or Nicotiana tabacum var. White Burley;

c) molecular tests like PCR.