The tour estimated Illinois' average corn yield at 133.2 bushels per acre, based on 169 field samples taken by crop scouts in the state's major growing areas Wednesday.

This compared to the tour's 1997 Illinois estimate of 116.6 bushels and the five-year tour average for Illinois of 132.4.

Estimates for seven individual Illinois crop districts on Wednesday ranged between 114.4 and 146.9.

The US Department of Agriculture, in its August 12 crop production report, estimated Illinois' average statewide yield at 143 bushels, compared to 129 bushels in 1997. The average US yield was estimated at 130. Illinois is typically the US' second-leading corn producing state behind Iowa.

Tour participants took 13 different routes across Illinois, primarily concentrating on the central and northern regions. Afterward, "disappointment" was a word used frequently by participants in Wednesday's evening's discussion of survey results for corn.

Scouts said that the crop's maturity was mostly ahead of schedule, but also noted the effects of excessive moisture in the spring planting season and not enough moisture in July and August.

"I was a little disappointed in corn, since we were going through some of the Prime growing areas," said Alan Karkosh, who farms near Hudson, Iowa.

Several fields sampled in east central, northeast and central Illinois were very dry and in need of rain, scouts said, though conditions on some routes improved further West. Scouts also noted several instances of nitrogen deficiency in parts of fields, which was marked by yellowing plants and smaller than normal ears. This is often the result of excessive rainfall earlier in the growing season that leaches nitrogen, a key plant nutrient, out of the soil.

"It was planted under mostly adverse conditions, with too much moisture," said Garry Kepley of the Illinois Agricultural Statistics Service, who addressed the tour Wednesday evening. In addition to nitrogen leaching, the excessive moisture resulted in corn plants in some areas establishing shallow root systems, Kepley added.

Pete Leavitt, Chief executive officer for Weather Services Corp and a participant on the tour, said the lack of significant disease and insect problems and mostly-favourable weather during the corn crop's critical pollination phase likely led to heightened expectations ahead of the tour.

"It turns out we've got a corn crop that's less than great," Leavitt said. "I thought in some areas I would see corn a little better than it was. The surprises I saw tended to be more negative than positive."

Maturity levels of corn fields sampled ranged between the late milk and hard denting stages, crop scouts said. According to the Illinois Agricultural Statistics Service, 22 per cent of Illinois corn acreage was dented through last weekend, compared to 12 per cent at the same time a year earlier and the five-year average of 13 per cent.