Researchers at Agriculture Canada’s Brandon, Man., research centre are trying to find out more about potato viruses.
Potato virologist Rudra Singh started a survey in July 1998 to determine the presence and prevalence of common potato viruses and the virus content of home-grown versus imported potato seed sources.
Depending upon the virus and severity of infection, potato viruses can reduce yield by more than 50 percent. Even a low level of viruses can cause rejection of potato seed lots for certification.
Last summer, scientists surveyed 34 fields from the main seed potato production areas of Manitoba. Two early-generation seed farms were also included to examine domestic seed potato production.
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Leaf samples were collected and laboratory testing confirmed the presence of potato viruses. The number and percentage of plants with mosaic virus and leaf roll virus were recorded in each field.
The incidence of mosaic virus ranged from zero to 1.6 percent province-wide, while leaf roll virus ranged from zero to 0.6 percent. Virus levels in Manitoba, whether from domestic or imported seed sources, were low compared to 2.5 to 10 percent found elsewhere in Canada.
These findings are preliminary because a number of surveyed fields had been rogued of diseased material.
To complete the 1998 survey, a post-harvest test of 200 tubers per field is being conducted at the federal potato research centre in Fredericton, New Brunswick. This test will determine the true virus content of the seed potatoes sampled.
Debbie McLaren, crop production pathologist at the Brandon research centre, has secured funding to work on virus identification and aphid monitoring in Manitoba.
The new survey is designed to help identify potato-growing regions less prone to virus diseases and plan virus management strategies. The Brandon centre will receive almost $75,000 over three years to fund this project.
Green peach aphids are vectors of potato leaf roll virus and potato virus Y that cause such economically significant potato diseases. In June and July 1999, researchers will set out pan and suction traps to monitor aphid movement in commercial and seed potato fields in southern Manitoba.
This monitoring will parallel the Aphid Alert program implemented at 12 sites in North Dakota and Minnesota by Edward Radcliffe from the University of Minnesota.
Disease management strategies that can minimize potato viruses:
- Ability to recognize symptoms in various potato cultivars.
- Removal of volunteer canola plants or other weeds that attract aphids from potato fields.
- Planting potatoes away from weedy areas and roguing fields early because disease is easier to detect in young plants.
To improve grower management practices, a potato virology and aphid monitoring workshop is planned July 6 at the Manitoba Crop Diversification Centre in Carberry.
There will be presentations on virus identification, disease outlook, aphid monitoring, transmission of disease and studies.
