Senate Democratic leader Robert Byrd warned yesterday of an "economic winter" unless President Reagan and Congress work together to reduce budget and trade deficits.

"The Democratic Congress is ready and willing to work with the president," the West Virginian said. "We need to pull together.

"I believe we are at a critical turning point in our nation's economic fortunes," he said, adding that the dramatic drop in the stock market was a warning "that an economic winter is coming unless we move quickly to change our nation's economic policy."

In the Democratic response to Reagan's weekly radio address, Byrd said, "Wall Street has sent Washington a message. It was a vote of no confidence and a yell for help all at once.

"In the most clear and stark terms, Wall Street is telling Washington that it wants a new economic policy and wants it fast." He added, "Unless Wall Street gets back a message from Washington that shows us working together, this week will come back to haunt us."

Byrd said it is not time to "fix blame" or play partisan politics. He added that both Congress and Reagan "must be willing to put aside their old assumptions" and meet with no options ruled out except the Social Security program.

The first meeting between Reagan and congressional leaders is scheduled for Monday.

He said automatic cuts under Gramm-Rudman-Hollings -- which would go into effect unless an agreement is reached -- are "too drastic, and meant to be."