Shipments of fertilizer, feeds, and agricultural chemicals are being rushed to crop-growing regions.

But farm suppliers are having to battle staff shortages and travel restrictions to accelerate their spring schedule.

The timing could not be worse for farmers preparing to plant crops.

There's fear that any disruption could reduce harvests, despite reassurances from Trump.

(SOUNDBITE) (English) U.S. PRESIDENT DONALD TRUMP, SAYING:

"The farm belt. And take a look at the farm belt. Take a look at areas out west ? But we can have large sections of - if we want to do it that way - we can have large sections of the country open.?

The United States and Canada are among the world's biggest grain exporters.

Nutrien is America?s biggest farm retail supplier.

Its CEO Chuck Magro told Reuters:

?Food security for the fall and for next year will be determined by what happens in the next two months in the Northern Hemisphere."

Farmworkers, meanwhile, are fearful of work being suspended, putting their industry and incomes at risk.

Alfonso Sandoval is the owner of Golden West Vegetables in California, and said it's the future of food security that?s at stake.

(SOUNDBITE) (English) ALFONSO SANDOVAL, OWNER GOLDEN WEST VEGETABLES, SAYING:

"Everybody is looking for stuff right now, so we need to cover the orders, here in California, out of state, we do a lot of out of state too so you know. We could be in trouble if they stop us, everybody here, we can not bring food to all the people, you know in the United States."