An agreement "in principle" on trade with Japan will keep U.S. beef and pork on a level playing field with competitors including Canada, Australia and South America, farmers said last week.

The announcement by President Donald Trump and Japanese Prime Minister Shinzo Abe at the G7 summit in France also injected a hint of optimism for farmers battered by market challenges due to lack of progress on trade deals across the globe and re­­newable fuel waivers domestically. The trade agreement, which will lower tariffs on U.S. beef and pork, is expected to be signed in September.

"We look forward to rapid...