The government charged yesterday that Montgomery Ward & Co. illegally paid some women employes less than their male counterparts. It asked a federal judge for a nationwide injunction to halt the alleged practice.

In a suit filed in U.S. District Court in Phoenix, Ariz., the Equal Employment Commission charged that the giant retailer discriminated against women department managers, in violation of the Equal Pay Act. It said the women in Phoenix were paid less than male managers at a Glendale, Ariz. store.

CHRYSLER PRICES: Completing the auto industry's first round of new model price hikes, Chrysler Corp. said yesterday it is boosting the sticker price on its 1980 cars an average of $359 or 5.1 percent.

The increase fell generally in line with those announced earlier by General Motors Corp., Ford Motor Co., American Motors Corp. and Volkswagen of America.

Chyrsler attributed $300 of the average increase to "new vehicle costs associated with meeting government regulations for fuel economy, emissions, safety and noise standards."

CROP ESTIMATE: The agriculture department raised its estimate yesterday of this year's record corn crop by 2 percent to 7.39 billion bushels, 4 percent more than last year's record.

With weather generally favorable over the past month, national average corn yield rose to 106.4 bushels per acre, compared to a September estimate of 104.6 bushels.

Last year the corn crop was 7.08 billion bushels and average yield was 101.2 bushels, surpassing 100 bushels an acre for the first time.

HEARINGS SCHEDULED: John Heimenn, U.S. comptroller of the currency, told reporters that his office will hold public hearings Oct. 22 and 23 on a request by Marine Midland Bank of New York to change from a state bank into a nationally chartered institution.

Hong Kong & Shanghai Banking Corp has been seeking approval of its request to buy control of Marine Midland and Marine Midland is strongly in favor of the proposal.