Chicago corn futures edged lower on Friday, staying on course for a weekly loss, as concerns about export delays following storm damage continued to hang over the market.
Moderate weather in the U.S. Midwest also capped prices by suggesting scope for late yield gains before the upcoming corn and soybean harvest.
Soybeans futures ticked up as a run of export sales countered worries over disruption to grain logistics caused by Hurricane Ida. Wheat also edged higher, consolidating like corn and soybeans near multi-week lows.
Attention in grain markets was turning towards the U.S. Department of Agriculture's (USDA) 10 September monthly supply and demand estimates.
Investors were also awaiting monthly U.S. jobs data on Friday. The most-active corn contract on the Chicago Board of Trade (CBOT) was down 0.9% at $5.20-3/4 a bushel by 1159 GMT, near a seven-week low touched on Thursday.
Grain shippers reported more damage from Ida to their terminals as Cargill Inc confirmed damage to a second facility, while power outages across southern Louisiana kept others shuttered.
"Stakeholders are still concerned about the effects of Hurricane Ida on export loading infrastructure," consultancy Agritel said in a note.
However, strong export demand was helping underpin soybean prices. The reported export sales of U.S. soybeans in the week to Aug. 26 at more than 2 million tonnes, topping a range of trade expectations.
Commodity brokerage StoneX on Thursday raised its estimates of average U.S. corn and soybean yields in the upcoming harvest.
CBOT soybeans were up 0.5% at $12.89 a bushel, while wheat added 0.2% to $7.18-1/4.
Wheat traders were continuing to assess mixed northern hemisphere harvests, which have raised concern of tight milling wheat supplies, while shifting their focus to developing southern hemisphere crops.
Widespread rains across Argentina's main farming regions have brought relief to wheat farmers ahead of the 2021/2022 harvest, a climate expert said on Thursday.