PARIS/MANILA - Chicago wheat, corn and soybean futures slid on Thursday as investor fears of an economic downturn and improved sentiment over U.S. crops shifted attention from war disruption to Black Sea exports.

Ongoing talks over a shipping corridor for Ukrainian grain and a U.S. pledge to help avert sanctions repercussions on Russian food and fertiliser exports also tempered concerns about the war blockade on Ukraine's ports.

The most-active wheat contract on the Chicago Board of Trade (CBOT) was down 1.6% at $9.73 a bushel by 1153 GMT, after hitting its lowest since March 1 at $9.60-3/4. CBOT corn dropped 2.6% to $6.75-1/2 a bushel, while soybeans fell 2.2% to $14.44-1/2 a bushel.

J.P.Morgan analysts in a note said "stymied investor risk appetite amid discussions of a humanitarian export corridor for Ukrainian food exports, downside global growth risks and hand-to-mouth consumer buying" had contained prices despite tight global supplies.

Crude oil fell further as investors feared that interest rate rises to quell inflation would tip economies into recession and curb demand. Moderate temperatures forecast into early July in the U.S. Midwest have eased worries about crop stress following a heatwave last week, despite limited expected rainfall.

Hot weather has also aided early wheat harvesting in the United States and Europe, creating seasonal supply pressure despite expectations of mixed yields following drought this year.

"Markets are expected to remain volatile in the coming weeks and weather conditions will continue to be monitored, particularly during the crucial corn flowering period in July," consultancy Agritel said in a note.

Grain markets continue to assess diplomatic talks over Black Sea grain shipments. A Turkish delegation will travel to Russia this week to discuss details of a possible sea corridor to export Ukrainian grain, Turkish presidency sources said on Tuesday. Countries should ask the United States for help if they have problems importing Russian food and fertiliser, U.S. State Department Bureau of Economic and Business Affairs Assistant Secretary, Ramin Toloui, said on Wednesday.

However, Russian strikes on the Ukrainian port city of Mykolaiv on Wednesday, which damaged grain terminals operated by international merchants Bunge and Viterra, kept traders sceptical about the chances of a sea corridor deal. 

(Reporting by Gus Trompiz in Paris and Enrico Dela Cruz in Manila; Editing by Uttaresh.V, Rashmi Aich and Barbara Lewis)