Wheat futures surge on slow harvesting, poor crop conditions

* Wheat contracts up as much as 6% after USDA crop report

* Corn bounces from 2-1/2-year low, soybeans firm

CHICAGO, July 5 (Reuters) - U.S. wheat futures surged on Wednesday as slow winter wheat harvesting and deteriorating spring crop conditions fuelled buying and short covering that lifted prices from 2-1/2-week lows.

The wheat rally pulled corn up from 2-1/2-year lows despite expanded plantings and recent rains that lessened concerns about drought-reduced yields.

Soybeans firmed on spillover support from wheat and worse-than-expected crop ratings in a weekly U.S. Department of Agriculture (USDA) report on Monday.

Wheat led grains markets higher after the USDA on Monday said just 37% of the winter crop was harvested as of Sunday, versus 52% last year. The agency also unexpectedly cut its spring wheat rating as rains failed to improve conditions.

"We are very tight in wheat supplies as the northern hemisphere starts to harvest," said Mike Zuzolo, president of Global Commodity Analytics.

"The hard red wheat is leading, mainly because they just can't get into the field in the state of Kansas to get the wheat out. The (spring wheat) conditions were also supportive."

Chicago Board of Trade September soft red winter wheat was up 27-3/4 cents at $6.69-1/2 a bushel at 12:18 p.m. CDT (1718 GMT). September hard red winter wheat gained 46 cents to $8.42-1/2 a bushel, while September spring wheat rose 46 cents to $8.55-1/4.

CBOT December corn rose 3 cents to $4.96-1/2 a bushel after earlier dropping to $4.85-1/2, the lowest for a most-active contract since January 2021. November soybeans gained 6 cents to $13.59-3/4 a bushel.

Recent rains and forecasts for further showers have reduced worries about early season dryness in the heart of the Midwest.

The USDA rated 51% of U.S. corn in good-to-excellent condition, up a point from the prior week. Soybean conditions, however, fell by a point.

Ratings for both crops have been declining for several weeks due to an expanding Midwest drought. (Reporting by Karl Plume in Chicago Editing by Marguerita Choy)