WHEAT prices hit a two-year high yesterday of $7.11 (£4.47) a bushel on the Chicago Board of Trade as worsening weather continues to ravage Russia’s grain crops and heavy rains in Pakistan are estimated to have destroyed 15 per cent of that country’s crop. Wheat prices soared 42 per cent in July, the biggest monthly gain in at least 51 years, as a severe Russian drought destroyed one-fifth of that country’s wheat crop.