Chicago corn futures slid for a fifth consecutive session on Monday as the harvest of a bumper U.S. crop gathered pace after being slowed down by rains, while soybeans ticked higher after two days of falls.

U.S. wheat eased, declining for a fourth session in five, as the market faced stiff competition from the Black Sea region.

The Chicago Board Of Trade most-active corn contract was down 0.1 percent at $3.66-1/2 a bushel as of 0219 GMT, near the session low of $3.65-1/2 a bushel - the weakest since Oct 11.

Soybeans were up 0.1 percent at $8.57-1/2 a bushel, having lost 3.3 percent in the last two sessions, and wheat fell 0.4 percent to $5.12-1/2 a bushel.

"The corn market is under renewed pressure and soybeans have ticked higher today but prices remain capped by harvests gathering pace in the U.S. Midwest," said Phin Ziebell, an agribusiness economist at National Australia Bank.

"China is not buying U.S. beans which is crucial for the market and prices are likely to remain under pressure unless we see any adverse weather in Brazil where planting for next crop are underway."

The U.S. Department of Agriculture said private exporters cancelled sales of 180,000 tonnes of U.S. soybeans to China, the world's biggest buyer, as the two nations remained locked in a trade war.

The USDA's weekly U.S. export sales figures for both soybeans and corn, released on Thursday, came in well below trade expectations.

Soybean planting by Brazilian farmers for the 2018-19 season progressed to 34 percent of the expected area last week, way ahead of seeding at the same stage last year as favourable weather in most regions speeded up field work.

An AgRural consultancy weekly report on Friday said overall soy planting in Brazil advanced 14 percentage points from the previous week. For comparison, at this time last year planting was at 20 percent of the area. The five-year average is 18 percent.

In the wheat market, exporters from the Black Sea region continued to pose stiff competition.

Ukraine's agriculture ministry has increased its forecast for the 2018 grain harvest to 64 million tonnes from 63.1 million tonnes, acting minister Maxym Martyniuk said on Saturday.

Large speculators trimmed their net short position in CBOT corn futures in the week to Oct. 16, regulatory data released on Friday showed.

The Commodity Futures Trading Commission's weekly commitments of traders report also showed that non-commercial traders, a category that includes hedge funds, increased their net short position in CBOT wheat and trimmed their net short position in soybeans. (Reporting by Naveen Thukral; Editing by Subhranshu Sahu)

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