NEW YORK—Commodities fell sharply Monday as another big drop in crude prices prompted traders to shed copper, corn and other hard assets as alternative investments.

Crude tumbled as much as $5 a barrel during the day on a host of bearish news items, chief among those investors’ belief that Tropical Storm Edouard wouldn’t damage oil and natural gas facilities in the Gulf of Mexico.

Corn for December delivery 29.5 cents to settle at $5.555 a bushel on Chicago Board of Trade, the lowest settlement price since March 24. The contract has plunged 30 percent from June highs re...