UPDATE 1-Speculators boost net long corn stake for 5th straight week
* Speculators expand long stake in corn, soy
* Speculators go long on wheat; first time in 1-1/2 years (Adds details, graphic, byline)
CHICAGO, July 20 (Reuters) - Large speculators raised their net long stake in corn to the biggest in more than three months as the most extensive drought in the United States in 56 years triggered a sharp rise in corn prices, regulatory data released on F rid ay showed.
The Commodity Futures Trading Commission's weekly commitments of traders report also showed that noncommercial traders, a category that includes hedge funds, boosted their net long stake in soybeans to the most since early May in the five trading days ended July 17.
Noncommercials also reversed their stake in CBOT wheat, moving to a net long for the first time since February 2011, when severe drought in Russia spurred a rise in wheat prices.
In corn futures, the noncommercials have expanded their net long position for five straight weeks as crop conditions have worsened to the poorest in 24 years.
In the trading period that ended Tuesday, the large speculators added 30,559 long positions and reduced 2,025 shorts, resulting in a net long steak of 156,610 contracts, the largest net long since the week ending March 27.
Speculators added 4,193 long soybean positions and 1,445 shorts for a net long stake of 221,424 contracts.
The conditions of each developing crop have deteriorated due to the searing drought, with the U.S. Agriculture Department this week putting so-called good to excellent ratings of the corn and soy crops at the lowest since 1988.
Futures for both commodities rose to record highs on Friday at the Chicago Board of Trade.
Noncommercial traders added 13,905 long wheat positions and 352 short positions, resulting in a narrow net long stake of 10,725 long contracts.
The move came as a leading Russian grain analyst cut the forecast of the new Russian crop, also due to drought, in the major Black Sea exporter.
(Reporting by Michael Hirtzer; Editing by Leslie Gevirtz and Dan Grebler)