* U.N. and experts say Middle East driest in decades
* Rain-fed cereal areas in Syria and Iraq hurt
* Experts say poor management worsens drought's impact
* Increased need for imports will pressure global prices
By Suleiman Al-Khalidi
AMMAN, March 7 (Reuters) - The Middle East's driest winter in several decades could pose a threat to global food prices, with local crops depleted ...