Sen. Frank Church (D.-Idaho) won the crucial Oregon Democratic primary yesterday, beating former governor Jimmy Carter of Georgia and write-in candidate Gov. Edmund G. Brown Jr. of California by a comfortable margin.

Oregon was one of six presidential primaries held yesterday.

As expected, Carter sailed to easy victories in the Arkansas, Kentucky and Tennessee primaries, while Church won his home state of Idaho and Brown scored an overwhelming win in Nevada.

On the Republican side, President Ford defeated former governor Ronald Reagan of California in a mild upset in Kentucky, but Reagan beat Ford by wide margins in Nevada, Idaho, and Arkansas. At midnight, CBS rated both Tennessee and Oregon too close to call.

With 17 per cent of the vote counted in Oregon, Church led with 40 per cent, followed by Carter at 30 per cent and Brown at 15 per cent.

Carter's poor showing in Oregon, coming after his unimpressive victory over Rep. Morris Udall (D.-Ariz.) in Michigan and his loss to Brown in Maryland last week, may slow the Georgia peanut farmer's bid for the Oval Office.

With almost all votes counted in Kentucky, Ford led Reagan by 51 per cent to 47 per cent.

With yesterday's results, Carter passed the 800 mark in the delegate count. Democratic candidates need 1505 to receive the nomination.

Ford now leads Reagan in the Republican delegate count by 752 to 621.

The faltering campaign of Gov. George Wallace of Alabama fared poorly against Carter in Tennessee where the former Georgia governor had opened up a 78 per cent to 11 per cent gap, and in Kentucky, where Carter won by 59 per cent to 17 per cent.

Earlier in the day, Carter told newsmen in Warwick, R.I., that a poor showing in one or two of yesterday's primaries "would not be a major strategic blow."