Potato Yellow Vein Disease

Potato Yellow Vein Disease is common in some countries in South America. It is apparently caused by a virus transmitted by the whitefly Trialeurodes vaporariorum.

Symptoms of Potato Yellow Vein Disease

Soon after infection, bright yellowing of minor veins (tertiary) is evident.
As potatoes disease progresses, secondary veins and leaf lamina become yellow, usually leaving primary veins green.
Stunting or weakness of the plants have not been detected, but tuber yield can be reduced by 50%.
Secondarily affected potatoes plants show vein yellowing right after emergence.

Management

Attempts to control the vector by pesticide applications have led to an increase in disease incidence because populations of natural biological control are affected.

Elimination of infected potato plants in and around fields, as well as weeds such as Solanum nigrum and Lycopersicon sp., reduces sources of infection.

The practice of interplanting beans with potatoes should be avoided because populations of the vector increase in beans.

Planting seed potatoes produced in areas where the disease does not occur also prevents having sources of infection for the potato crop.

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Mint can purge potato pest

Original article

Rotating potatoes with alfalfa or spearmint may offer farmers a sustainable
way to reclaim crop soils contaminated with corky ringspot disease,
Agricultural Research Service studies suggest.

Corky ringspot--a brown, bull's-eye blemish on tubers--is caused by the
tobacco rattle virus, which is passed into potato plants by wormlike soil
organisms called stubby root nematodes. In affected areas such as Washington's
Columbia Basin, where 5,000 acres are contaminated, potato farmers have
either stopped growing the crop altogether or resorted to fumigating soil to
kill nematodes that spread the virus.

At $250 per acre, however, fumigation is expensive. Plus, it kills soil
organisms other than nematodes. A more sustainable, pest-specific approach
could come from rotating potatoes with alfalfa or spearmint to rid the
nematodes of their viral payload, according to scientists Rick Boydston,
Pete Thomas and Hassan Mojtahedi. Boydston and Thomas are at ARS' Vegetable
and Forage Crop Production Research Unit in Prosser, Wash. Mojtahedi works
for Washington State University.

Their strategy is based on two observations: First, the virus can't survive
in alfalfa or spearmint, so the nematodes can't acquire it while feeding on
the plants' roots. Second, the nematodes naturally shed the virus from
their bodies by molting. Given enough time, the scientists reasoned,
nematodes that fed only on these plants eventually would rid themselves of
the virus, and thus pose little or no danger of infecting a subsequent
potato crop.

Indeed, in greenhouse trials, virus-bearing nematodes that fed on potted
alfalfa or spearmint plants for three months lost their ability to infect
disease-free potato plants. Conversely, nematodes that fed on tobacco,
a natural host of the virus, retained their ability to infect disease-free
potato plants.

Some farmers already practice this rotation but still fumigate fields with
a previous history of corky ringspot. The key, scientists emphasize, is to
eliminate weeds in alfalfa or spearmint crops where nematodes can acquire
the virus. These include hairy and black nightshade, downy brome, common
chickweed and prickly lettuce. They are among 38 weed species the
scientists have tested.