Treasury notes, which are backed by the full faith and credit of the U.S. government, are a reliable source of income even in the midst of a souring economy. Experts suggest that investors keep some portion of their portfolios in treasuries. Still, now is not the ideal time to buy treasuries. For starters, investors have begun crowding the treasuries market, driving the yield on 10-year notes below 3 percent for the first time since 2008. “I’m afraid that by suggesting that people need more, there can be some momentum-chasing,” says Jeff Tjornehoj, Lipper’s research manager for the United States and Canada. Meanwhile, if the economy recovers enough, rising interest rates could plague treasuries.