Diesel prices are at record highs.

This is happening just when many U.S. farmers need fuel for combines and tractors.

They are harvesting soybeans and corn, two of the nation's largest crops.

The price jump adds to an already hard year.

Costs for fertilizer, seeds and equipment are also higher.

Diesel hit a record U.S. price on Sept. 4.

It averaged $5.85 a gallon for the first time.

The six-month war with Iran had disrupted the world's fuel supply.

By Friday, the average had risen to $6.05 a gallon, according to AAA.

Prices are now 60% higher than before the U.S. and Israel launched the war in late February.

At that time, the average was about $3.76.

Paul Mitchell is a professor at the University of Wisconsin-Madison.

He said the prices hurt.

He said the cost affects not just harvesting.

It also affects hauling grain and silage from fields to farms and then to buyers.

Jason Kurtz is a corn and soybean farmer near Forest City, Missouri.

He said he was paying twice as much for diesel this year.

His combine uses 200 gallons a day.

He expected to run it for 30 days.

Kurtz is 49 years old.

He said he still had to run the machines and use the diesel.

So it cuts into his bottom line.

He said his finances were already tight after paying more for fertilizer and chemicals.

Kurtz voted for President Donald Trump.

He said he planned to delay some farm work.

He hoped diesel prices would fall.

Mitchell said farms with little cash are struggling most.

They find it hardest to decide what to cut.