Guardian: Russia’s prime minister, Vladimir Putin, has announced a ban on grain exports after millions of hectares of crops perished in the worst drought in more than a century. High temperatures, lack of rain and wildfires have devastated more than a third of cultivable land in Russia, the world’s fourth largest grain exporter. News of the ban pushed wheat prices to a 23-month high on commodities markets and raised concerns about a boost in food prices worldwide. Putin said the …