Chicago soyabean futures slid lower on Tuesday as the risk of a drop in demand for livestock feed due the closure of several US meat packing plants hung over the market.
Corn also inched lower as it tracked hesitant movements in crude oil markets. More than a third of the US crop goes to ethanol biofuel.
Wheat eased as steady US crop ratings tempered concern about possible frost damage in parts of the US Plains.
Several US meat processing plants temporarily closed in the last week after outbreaks of the novel coronavirus among workers, prompting fears of a knock-on effect on demand for soyameal widely used in feeding livestock.
Jim Gerlach, president of A/C Trading, said it will be hard for soya supplies to tighten enough to offset the demand destruction from a backup at the slaughterhouses.
Soyabean imports by China, the world's top buyer of the oilseed, fell 13% in March from a year earlier to a more than five-year low, customs data showed on Tuesday, after rains delayed cargoes from Brazil and the coronavirus outbreak dented demand.
The most-active soyabean contract on the Chicago Board Of Trade (CBOT) was down 7-1/4 cents at $8.47 a bushel at 10:26 a.m. CDT (1526 GMT), after losing more than 1% on Monday.
Corn fell 4 cents to $3.27-1/2 a bushel and wheat slipped 7-1/4 cents to $5.47-3/4 a bushel.
Plunging fuel consumption as many countries impose lockdown measures to curb the coronavirus has kept corn near a 3-1/2 year low.
In a weekly crop report released after the market close on Monday, the US Department of Agriculture (USDA) estimated that 62% of US winter wheat was in good or excellent condition, stable on the week and slightly above the year-earlier score.
Meanwhile, Egypt, the world's largest wheat buyer, bought 120,000 tonnes of Russian wheat in a tender, which was less than anticipated.