WERA089: Potato Virus and Virus-Like Disease Management
Statement of Issues and JustificationVirus diseases in potatoes create a costly situation requiring limited generation seed programs and incorporating the use of multiple pesticides to minimize the loss of yield and quality in commercial crops. Some of the more prevalent viruses of potatoes include alfalfa mosaic virus, Potato leaf roll virus, Potato virus M, Potato virus S, Potato Virus X and Potato virus Y (PVY). Many of these viruses have been causing crop yield losses for decades and in the west, the dominant cultivar, Russet Burbank, is very susceptible to a wide range of virus diseases. Release of new varieties highly susceptible to PVY has dramatically increased issues with this virus throughout the western potato growing regions. Substantial yield losses and rejections for certification of seed lots have resulted in tremendous dollar losses to growers. PVY is of particular concern because insecticides have shown little effectiveness for control and other management options such as rouging do not work effectively for managing this virus. Additionally, multiple strains of PVY now occur throughout the western growing region creating difficulties in identification and further exasperating the efforts to reduce the impact of PVY.
There are also the public and environmental concerns surrounding the use of pesticides on potatoes. Potato growers are faced with the potential loss of key pesticides because of cancellation of registration. In addition, difficulties of developing new information for re-registration or development of new pesticides is becoming more difficult each year. Lastly, pest resistance to current pesticides is always of concern. Certainly, the loss of pesticides or loss of effectiveness will reduce yield and increase quality losses if alternative solutions are not developed.
Emerging viruses and new virus strains of indigenous viruses pose a constant threat to seed and commercial potato production. In the last decade, PVA and PVM were not known in the West. PVM seems to have been contained by the efforts of certification programs, while PVA appears to have become endemic in certain regions. Effects on yields and tuber quality from these viruses and new strains of older viruses are not well known and are confounding an already difficult situation. . New strains of PVY, particularly those that also produce internal tuber problems along with yield reduction, were not known in the US until relatively recently. They are now commonly found throughout the west. Recently, a new disease causing zebra chip symptoms in daughter tubers in south central US potato production areas has resulted in tremendous economic losses in chip potatoes. The disease is now known to be caused by a new bacterium (Liberibactor) transmitted by potato psylids. Tomato Spotted Wilt Virus (TSWV) has shown up from time to time in the western region and while not currently a problem, this and other viruses are significant problems in areas where they have become endemic. Also, when a new virus or virus strain is detected, there is rarely specific antiserum available to allow for widespread surveys of seed programs. Emerging viruses pose a wider threat to the potato industry as a whole simply because the industry moves more seed each year from more diverse areas to answer production needs.
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