GRAINS-Corn rises on fears US yields could fall short of estimates

CANBERRA, Oct 17 (Reuters) - Chicago corn futures extended gains into a fourth session on Friday and were set for their first weekly gains in five weeks, as traders speculated that U.S. harvest yields may be lower than predicted.

Soybean futures rose after data showing a much stronger than expected September soy crush. Wheat followed corn and soy higher, helped by short-covering after prices fell to five-year lows earlier in the week.

All three contracts were lifted by a weakening of the U.S. dollar making U.S. exports cheaper for buyers with other currencies. .DXY USD/

Commodity funds have been net buyers of all three crops since Tuesday, traders say.

The most-active corn contract on the Chicago Board of Trade (CBOT) Cv1 rose 0.4% to $4.23-1/2 a bushel by 0601 GMT, up 2.5% from last Friday.

CBOT soybeans Sv1 climbed 0.2% to $10.13 a bushel and were set for a 0.6% weekly gain, while wheat Wv1 was 0.3% higher at $5.03-3/4 a bushel and up 1.1% for the week.

All three crops have fallen sharply since 2022 due to abundant supply.

Market moves remain cautious due to a U.S. government shutdown halting the release of key crop data, but traders continue to estimate supply and demand.

"Indications are coming in a bit disappointing here and there," said Tobin Gorey, founder of Australian consultant Cornucopia. "There's speculation that we saw peak yield numbers a while ago and it's come back a bit."

However, prices are still trading in the range they've been stuck in since July and there is little prospect of significant upside since the global market is comfortably supplied, Gorey said.

Hanging over the market is an escalation in U.S.-China trade tensions over the last week that dampened hopes that China could resume purchases of U.S. soybeans and other crops.

China's boycott of U.S. soy has weighed on U.S. prices. High premiums for Brazilian beans mean China has yet to secure much of its supply for December and January, sources said, but Beijing has state reserves it could use to meet near-term needs.