Idaho potato king Jack Dimplot and 13 other individuals and companies were charged yesterday by the Commodity Futures Trading Commission with alleged price manipulation in the May 1976 Maine potato futures default.

The administrative complaint filed by the agency resulted from a year-long investigation of the default individuals and companies face panalties of $10,000 for each violation and possible prohibitions against their trading on all of the nation's contract markets.

The New York Mercantile Exchange was also charged with failing to enforce its own rules and permitting the default to occur.

Those accused of trying to manipulate prices down-ward, of exceeding speculative trading limits and of violating cease and desist orders issued by the CFTC were Simplot and two of his companies, J. R. Simplot Co. and Simplot Industries, Inc., of Boise, Idaho, his business partner, Peter J. Taggares trading firm of Othello, Wash., the joint Simplot-Taggares firm, Sim-Tag Farms of Othello, Wash.; Harry Lenton and H. Dean Summers of Boise and Stephen Sundheimer of New York City.

Those charged with manipulating prices upward and of violating speculative limits were Harold Collins of Oswego, N. Y., Wayne County Produce, Inc., of Savannah, N. Y., Casper Marysohn of White Plains, N. Y., Lynnewood Export Corp. of New York City and Manning Stoller of Lexing, Mass.