Wheat, which in the last session ventured a toe beyond the $2-a-bushel line in its premium over corn, got the whole foot over this time.
Sure, wheat hardly raced ahead in Chicago, adding 0.7% to $6.58 ¼ a bushel for December delivery.
But that was enough to expand its premium over December corn futures to $2.09 ½ a bushel.
It earned Chicago wheat another technical feat too, with the December lot closing above its 50-day moving average for the first time in more than three months.
Furthermore, the represented outperformance of commodities as a whole, with the CRB index dropping 0.4%, depressed by fears of a looming stand-off in Washington over the US budget and debt ceiling.
'Export market red hot'
Wheat's support continued to come from a drip feed of supply disappointments at a time of firm demand, as highlighted by the strong starts by US and European Union exports to 2013-14, and with Russia expected soon to begin purchases for intervention stocks.
"December wheat is up only $0.16 a bushel from summer lows despite a 31% increase in Chinese wheat imports since June 1, and larger 2013-14 US wheat export inspections since June," Richard Feltes at RJ O'Brien said.
US Commodities said: "The wheat market has improved fundamentals. This is the reason December wheat is now $2 a bushel over December corn.
"The US export market remains red hot."
Tuesday's main supply scare was of frost in Argentina, adding to the pressure on a crop already being tested by dryness.
Temperatures last night fell as low as -5 Celsius in parts of Buenos Aires, the main grain-growing province, besides in Cordoba and parts of Santa Fe.
However, early quality data on Canada's spring wheat harvest showed a decline in protein levels there, to 12.4-13.1%. Last year's spread was 13.1-14.2%.
That added to the concerns that quality wheat, at least, may prove in shortish supply.
Indeed, Kansas hard red winter wheat for December outperformed, adding 1.0% to $7.05 a bushel, as did Minneapolis hard red spring wheat for December, which recovered from a three-year closing low in the last session to end up 0.9% also at $7.05 a bushel.
Wheat's gains contrasted with a tumble in December corn of 1.0% to $4.48 ¼ a bushel, depressed by the prospect of a pick-up in the US harvest, and so a boost to supplies, amid continued talk of better-than-expected yields.
"Harvest pressure has corn on the defensive," CHS Hedging said.
"Farmers are expected to get back in the field middle of the week and really gain speed into the weekend."
"Weather for the week ahead is mostly clear for harvest to advance quickly into the weekend," Benson Quinn Commodities said, adding that "harvest pressure is seen capping any gains".
'Plant in the dust…'
Meanwhile, Paul Georgy, president of Chicago-based broker Allendale, played down talk that the Argentine dryness would prompt a switch by farmers to soybeans, which can be later sown, from corn in their spring planting schedules.
"It seems a little early to be making those decisions as optimum corn planting time is mid-September to mid-October," Mr Georgy said.
Besides "the rule of thumb in the US is 'plant in the dust, your bins will bust'," he said, citing the example of current Corn Belt crop being harvested, which "was planted early in dry conditions", but with yields which "continue to be reported in the mid-200s" bushels per acre.
At least Colombia offered some demand hope, in buying 180,000 tonnes of US corn, revealed through the US Department of Agriculture's daily alerts system.
Soy yield caution
Soybeans too felt harvest pressure, but countered it with some buying on talk of a Midwest frost on October 8-9, which could affect some of the later-developing crops, besides USDA data overnight showing that rains last week had stabilised crops, but not fostered improvement, as investors had expected.
"Crop scouts caution against reading too much into the generally better-than-expected early soybean yields, given the late-season onslaught of warm/dry weather during pod-fill," Mr Feltes said.
Furthermore, the oilseed got a lift from rising prices of soymeal, one of the main soybean-processing products, which added 0.8% to $412.30 a short on in Chicago, for December delivery, helped by widening basis in Brazil, where prices have been underpinned by logistical hiccups.
November soybeans closed up 0.4% at $13.12 ½ a bushel in Chicago.
Soft commodities were broadly firmer too, including raw sugar, which closed up 1.0% at 17.42 cents a pound in New York for October delivery, the best close for a spot contract in four months
The sweetener was helped by Unica data showing a drop in sugar production in Brazil's key Centre South region in the first half of this month, besides by further strength in the real against the dollar.
The Brazilian currency's strength, in boosting the dollar value of Brazilian assets, helped lift arabica coffee too, which ended up 0.7% at 117.85 cents a pound for December.
Cotton for December gained 0.1% to 84.38 cents a pound in New York, helped by a further drop in reserves for delivery against futures, to 14,961 bales, the lowest in 10 months.