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Boosting Potatoes' Natural Ability to Protect ThemselvesBy Jan Suszkiw
December 2, 2003
Potato and other plants have the means to defend themselves from hungry insects and microbes that cause disease. But some plants don't mobilize these defenses in time to do much good. Now, Agricultural Research Service scientists are testing a way to snap such sluggish plants to attention and steel them for battle.
In studies at Prosser, Wash., the scientists are spraying the plants with salicylic acid, a substance familiar to many as an ingredient in aspirin. In plants, it functions as a natural signaling compound that triggers a protective response called "systemic acquired resistance," or SAR.
Plant scientists have known about SAR for years, but only recently have SAR-activating products become available for use on crops including tomatoes, lettuce and spinach. Healthier plants and reduced pesticide use are among the benefits associated with activating SAR.
But according to Roy Navarre, a molecular biologist at the ARS Vegetable and Forage Crops Research Unit in Prosser, little is known about such benefits in potatoes, a crop that generates nearly $3 billion annually in U.S. farmgate sales.
So, earlier this year, he and colleagues kicked off a project to find out. Through lab and field studies, their objective is to determine which SAR activators work best, in what parts of the potato plant, for how long, and at what doses.
Scientists also test the activated plants' SAR defenses by inoculating the plants with organisms such as late blight fungus, white mold, potato virus Y, green peach aphid and Columbia root-knot nematode. Chemical fumigants are a staple defense against the latter pest, but pumping them into the soil can cost farmers $250 an acre.
Navarre is encouraged by the studies' early results, especially against viruses, for which there is no direct method of control. Read more about this research in this month's issue of Agricultural Research magazine.
ARS is the U.S. Department of Agriculture's chief scientific research agency.