The national price for regular unleaded gasoline dropped 5 cents over the past week and 78 cents in the last nine weeks to US$2.26 a gallon, according to the Energy Information Administration's weekly survey of service stations.

That's the lowest price since mid-February, and comes after prices hit a summer high of US$3.04 a gallon in early August.

Bush said the United States needed to reduce its reliance on oil, especially from imports, and that developing alternative energy fuels, such as cheaper ethanol, would help the US economy and improve the nation's energy security.

"Let me just put it bluntly: We're too dependent on oil," Bush said. "Low gasoline prices may mask that concern."

He said the United States needed to develop alternative energy fuels because America has to import 60 percent of its oil to meet domestic demand, and some of that crude comes from "countries that don't particularly care for us."

Bush did not unveil any new initiatives but promoted his administration's program to fund research for making ethanol from less expensive wood chips, switch grass and other agricultural waste products. Most US ethanol is made from higher-priced corn.

"I believe so strongly that this country has got to use its talent and its wealth to get us off oil," Bush said. "Probably the fastest way we can begin to change the consumer habits -- is to promote hybrid vehicles."

Bush mentioned a tax credit of US$3,400 for new hybrid cars, which run on a combination of gasoline and electricity. He also envisioned next-generation batteries powering cars for the first 40 miles (64 km) of a trip.

Bush also applauded those using E-85, a blend containing 85 percent ethanol and 15 percent gasoline.

Bush's call for more alternative fuel use won applause from the 1,500 people in the audience, mostly from the agricultural and energy sectors.

However, during Bush's energy speech, one woman stood up and yelled, "Out of Iraq now!" and "What are you doing?" and pumped her fist in the air before security removed her.

Ethanol is blended into gasoline to make a cleaner-burning fuel and stretch available domestic supplies.

Last year, the United States used 14 percent of its corn crop to make ethanol, with usage forecast to rise to 20 percent this year.

Companies are scrambling to build new ethanol plants to meet growing demand but with US corn supplies tight and grain prices rising, producers are looking for alternative ways to make ethanol.

On Thursday, the US Agriculture Department cut its estimate of the US corn surplus to 996 million bushels, the second-smallest carry-over figure in a decade.