One of the most serious diseases of potato is caused by Potato Virus Y (PVY). As seed tubers infected with this virus yield substantially less than uninfected ones, it is essential for potato production that seed lots have low virus levels. Thomas Döring of the Organic Research Centre has been involved in a study published this month in the journal Annals of Applied Biology, which points to non-chemical control options for PVY in Northern Europe.
PVY is transmitted by aphids in such as way that a very short time span is sufficient for the insect to acquire and transmit the virus. Many aphid species are able to transmit PVY as they make brief probings on potato plants when they are searching for host plants. These virus vectors are extremely difficult to control with insecticides, because the active ingredients are often not able to have an effect on the vector before the acquisition or transmission of the virus has occurred.
In the study, not a single aphid was found colonizing the potato plants, despite substantial variations in virus levels. This suggests that the practice to spray insecticides frequently fails to act against PVY and its vectors. This finding confirms the point of low efficacy of insecticidal treatments for controlling non-persistently transmitted viruses.
In addition, the study allowed the timing of the main virus transmission activity to be determined as the early part of the growing season, relatively shortly after the emergence of the potato crop. When vector flight occurs early, measures that interfere with the host locating and host contacting behaviour of the vectors have a great potential for virus control. In previous studies, straw mulch had been suggested to be an efficient tool for reducing virus diseases, especially under conditions of early vector flight. This was indirectly confirmed in the study area where further trials showed straw mulch had an outstanding efficacy for controlling PVY.
Kirchner SM, Döring TF, Hiltunen LH, Virtanen E, Valkonen JPT. 2011. Information theory-based model selection for determining the main vector and period of transmission of Potato virus Y. Annals of Applied Biology 159:414-427
For further details see: http://onlinelibrary.wiley.com/doi/10.1111/j.1744-7348.2011.00501.x/abstract.
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