Hello 

    In this issue I have found an article by Phil Nolte the seed potato specialist for the University of Idaho.  It sums up quite well why all the controversy has occurred over the potato wart issue and why the U.S is being so careful.

Until Next Week,

Usually when I sit down and write a column about potato disease management, the article deals with the familiar package of management techniques, including cultural and chemical control measures which can help combat a particular disease. I thought I might take a slightly different tack this time around and discuss another important method of disease management that's been making potato headlines lately: government intervention.

By now most of us are aware of the infestation of potato wart disease (caused by the fungus Synchytrium endobioticum) that was found on Prince Edward Island, Canada, this year. Potato wart has the distinction of being on the list of disease problems that fall under the Plant Quarantine Act of 1912. This legislation prohibits or restricts the movement into the U.S. of plant and plant-related materials that pose a disease or pest threat. In other words, this law provides the legal machinery to exclude potentially dangerous plant diseases. The Quarantine Act was actually passed in response to the devastation wrought on American chestnut groves in

the east by the importation of chestnut blight in 1904. The quarantine might have been a little too late - the disease had all but eliminated the American chestnut by the end of the 1930s.

One of the reasons that quarantines are instated is because imported diseases are often very nasty. In the area of origin for a plant disease, where the pest and the host plant have evolved together, a sort of equilibrium has usually been reached. After many centuries of coexistence, both pest and plant will have evolved to a state where the pathogen is not too virulent and the host is not too susceptible. Not exactly a harmonious relationship, but much better than what happens when the same pathogen comes into contact with the non-adapted host population that it might encounter on a different continent. There are many examples of such disease introductions and the serious consequences that resulted, including potato late blight into Europe and North America, the aforementioned chestnut blight, Dutch elm disease, and white pine blister rust, just to name a few.

Being the target of a quarantine is serious business and can be frighteningly expensive. The citrus industry in Florida has had to destroy literally millions of expensive citrus trees several times since 1912 because of the threat of citrus canker, a bacterial pest not native to the area. The cost to the Florida industry over the last 90 years, because of this disease, is conservatively estimated to be $40 million or more.

One final note: Those pesky inspectors who hassle you when you come in from a foreign country are not there just to harass innocent travelers. They are one of our first lines of defense against the intentional or inadvertent importation of plants and plant parts potentially carrying diseases that could pose a serious threat to U.S. agriculture, forests, or urban plantings. You would not believe the amount of stuff they intercept each and every day. Tip your hat and cooperate with those folks. What they do is important.

At presstime, the Prince Edward Island wart situation was under heavy discussion. It may be settled or still under negotiation as you read this. I am not trying to make potato wart a disease of the same importance as late blight or Dutch elm disease but, to be honest, we don't actually know. It is just for situations like this that there is a Plant Quarantine Act. Like it or not, sometimes quarantines are a necessary evil.

Nolte is extension seed potato specialist, University of Idaho, Idaho Falls, ID 83402; e-mail: pnolte@uidaho.edu