HELPING POTATOES HELP THEMSELVES
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 US studies 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 (Agricultural Research Service)
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 £120 an acre.
Navarre is encouraged by the studies' early results, especially against
viruses, for which there is no direct method of control.
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