Agriculture Secretary Bob Bergland said yesterday that wheat farmers will be ineligible for government aid on next year's crop unless they hold down production by the same amount as this year.

He said that the constraints would not raise prices for bread and other bakery products unless millers and bakers decided to buy more wheat, thus raising their own costs.

Bergland told reporters that price supports and rates for income subsidies would be the same as for the 1978 crop. Department economists said they expect the 1979 average price also to be about the same $2.75 a bushel.

Because of a price-stifling surplus of 1.17 billion bushels of wheat, continued restraints on new production were expected despite President Carter's statement that his administration eventually wants to get government out of agriculture.

"The person most competent to make a farmer's decisions is not a bureaucrat in Washington or anywhere else; it is the man or woman on the farm," Carter told about 10,000 persons gathered for a Mid-Continent Farmers Association convention in Columbia, Mo., Monday.

Bergland said that he expects the continued acreage controls to lead to a 1.81-billion-bushel crop next summer, with 1.14 billion left in the stockpile by 1980. About 1.82 billion bushels were grown this year, compared with 2.03 billion in 1977, the last uncontrolled harvest.

The wheat "set-aside" program is a tool for the government price supports, disaster relief and income subsidies.

Wheat gorwers were encouraged to idle one acre of every five acres they planted for the 1978 crop, and the Agriculture Department said it received cooperation from farmers controlling 75 to 80 percent of the nation's wheat acreage.

Most farm groups and members of Congress urged the same figure for the 1979 crop, to reduce surpluses built up because of depressed grower prices and four uncontrolled harvests.