CANBERRA, Oct 18 (Reuters) - Chicago wheat rose on Friday, supported by dry conditions in several big exporting nations and concerns about shipments from Russia, but still headed for a weekly loss amid pressure from low corn and soybean prices and a strong U.S. dollar.

Corn and soybean futures also eked out gains on Friday but were on track to end the week down as a rapidly advancing U.S. harvest pumps supply into the market and rain improves planting conditions in Brazil.

FUNDAMENTALS

* The most-active wheat contract on the Chicago Board of Trade was up 0.3% at $5.91-1/2 a bushel at 0050 GMT, while CBOT soybeans rose 0.5% to $9.93-3/4 a bushel and corn

climbed 0.3% to $4.07-3/4 a bushel.

* Wheat was nevertheless down 1.3% this week, with soybeans down 1.1% and corn down 1.9% from last Friday's close.

* Wheat fell to a three week low, corn a five-week low and soybeans a seven-week low this week and none are far from four-year lows reached earlier this year.

* Wheat has come under pressure from much-needed rainfall in the Black Sea region and some showers in the U.S., which improved planting conditions.

* The International Grains Council $(IGC)$ maintained its forecast for 2024/25 global wheat production at 798 million metric tons, with an upgrade for Kazakhstan offset by downgrades for Australia and Argentina, where dry conditions hit crops.

* However, a U.S. forecaster said a developing La Nina weather phenomenon could worsen a drought in the country's top winter wheat-producing area.

* Shipments from top exporter Russia could also decline due to government efforts to regulate exports by enforcing a price floor and raising export duties, analysts said.

* For corn, the IGC kept its forecast for 2024/25 global corn production unchanged at 1.224 billion metric tons, with small upward revisions for the United States and India offset by diminished crop prospects in Russia and Egypt.

MARKETS NEWS

* The S&P 500 and Nasdaq pared their gains to end essentially unchanged on Thursday, while the Dow notched a record closing high as investors parsed an array of mixed quarterly earnings and digested a series of robust economic reports.

(Reporting by Peter Hobson; Editing by Alan Barona)

((peter.hobson@thomsonreuters.com))