* Corn falls on USDA acreage data

* Wheat down 16% in June, biggest monthly drop since mid-2022

* Soybeans rise on USDA data

CHICAGO, June 28 (Reuters) - Chicago September corn plunged on Friday to contract lows after U.S. Department of Agriculture data showed far more acres planted with the grain than expected due to favorable spring weather.

However, soybeans gave up earlier gains to trade almost unchanged on lower-than-expected acreage, while wheat extended losses to record the biggest monthly drop in two years.

Plantings totaled 91.5 million acres for corn and 86.1 million acres for soy, the USDA said. Analysts had expected 90.3 million acres of corn and 86.8 million acres of soybeans, according to a Reuters survey.

"There's nothing friendly for corn, but beans came in close to the average trade guess," said Jim Gerlach, president of A/C Trading.

The most-active corn contract on the Chicago Board of Trade (CBOT) ended down 15 cents at $4.07-1/2 a bushel. September corn briefly fell below $4 a bushel, and ended the week down 7.5%. Soybeans fell 3/4 cent to 11.04 a bushel and wheat lost 6 cents at $5.73-1/2 a bushel.

Meanwhile, U.S. stocks of corn, soybeans and wheat as of June 1 were higher than the same time last year, the USDA said. U.S. corn growers' inventory on farms was the largest at this time of the year in more than three decades.

Wheat has dropped close to 16% so far this month, the biggest decline since June 2022.

"There's nothing bullish in wheat, and it's going down with the corn market," said Sherman Newlin, commodity broker at Risk Management Commodities.

Outside of the U.S. market, wheat planting for the current harvesting season in Argentina has also advanced rapidly over the past week due to recent rainfall over parts of the country's main farmland, the Buenos Aires Grains Exchange said in a weekly report published on Thursday.

The European Commission on Thursday raised its forecast for the European Union's main wheat crop this year and for EU wheat exports both in the current and next season. (Reporting by Renee Hickman in Chicago; Additional reporting by Naveen Thukral; Editing by Richard Chang)