A big, late Treasure Valley storage onion crop, combined with surging volumes from Mexico, has sent prices spiraling down.

Idaho and Oregon shippers don’t know when, or even if, markets will strengthen.

On Feb. 7, the U.S. Department of Agriculture reported a price of $6 for 50-pound sacks of U.S. No. 1 Spanish yellow hybrid onions shipping from Idaho and Oregon, down from $10 last year at the same time.

Colossals were $4-5, down from $8-8.50; jumbos $2.50-3.50, down from $6.50-7); and mediums $2.50-3.50, down from $8.

Red storage onion prices from Oregon and Idaho were slightly lower than last year. Twenty-five pound sacks of larges were $4-5, down from $6-7; and mediums were $3-4, down from $4-6.

White onions, however, were comparable to last year. On Feb. 7, 50-pound sacks of mediums and larges were selling for $9-12, about the same as last year at the same time.  

At those prices, Treasure Valley shippers are barely covering their packing costs, said Kay Riley, general manager of Nyssa, Ore.-based Snake River Produce Inc.

“We’re limping along, looking at the finish line,” Riley said.

Because of brisk movement from late  December through late January, Snake River still expects that finish line to come about on time, between mid-March and early April, Riley said.

But it would take “quite a turnaround” for markets to strengthen much between now and then, even with recent rains out of Mexico, Riley said Feb. 9.

A couple of factors have contributed to creating the current supply-exceeds-demand situation in the Treasure Valley, said Bob Komoto, sales manager of Ontario, Ore.-based Ontario Produce Co. Inc.

One, harvests for most valley growers were about three weeks later than normal. Two, packouts were better than expected. Shippers were left with a lot of onions to ship in a shorter period of time.

Rival deals haven’t made it any easier, Komoto said.

“Every little bit adds up, even if it’s just five loads from here, five from there,” he said.

Demand the final two months of the Treasure Valley deal is always difficult to gauge, Komoto said, and the 2011-12 shipping season was no different.