(Bloomberg News) England's hottest weather in more than three centuries is making Graham Birch, the country's best natural-resources fund manager for a decade, concerned about the state of his spring crop.

The corn and grasses grown for livestock on the 2,300-acre farm in the southwestern county of Dorset are already beset by the heat and lack of water, Birch said by phone on May 18. Rain will be needed soon to keep yields for wheat and rapeseed planted at the end of last year from dropping, he said.

European farmers are contending with the driest growing conditions in more than three decades. The European Union warned this week that soil moisture is now "critical" in at least six countries after some places had their driest March on record. France's soft-wheat crop, the EU's largest, will drop 12 percent, and German output will slide 7.2 percent, local forecasters said May 18.

"It's the spring crops I'm worried about because that's what's seeing some severe drought stress," said Birch. "It'd be nice to have some rain in the next couple of weeks."

Birch started a sabbatical from BlackRock Inc., the world's biggest money manager, in 2009 and formally left in 2010, when the team was managing $36.3 billion of assets. His BlackRock Gold and General Fund was the top performer among 858 U.K.- domiciled mutual funds over a decade, averaging gains of almost 23 percent a year, data from Morningstar Inc. show.

Ruined Crops

The former fund manager left BlackRock in a year in which drought or flooding from Europe to Canada ruined crops and spurred Russia to ban grain exports. Wheat rose as much as 90 percent and corn 87 percent, driving the United Nations Food Price Index to a record and draining global stockpiles.

Weather is threatening crops again this year, from drought in China to temperatures as high as 100 degrees Fahrenheit (38 degrees Celsius) in Kansas. Wheat traded in Chicago rose as much as 7.6 percent on May 18 as European forecasters predicted smaller harvests.

On Birch's farm, winter wheat and rapeseed were seeded in the fall when the ground was moist and roots could grow deep. Corn and grasses planted this spring in dry conditions didn't have those same conditions, he said.

"Forage, maize -- those crops are really suffering quite badly from the weather because they didn't have much of a chance to establish deep roots," he said. "The crops we planted in the autumn, they're looking OK at the moment."

Record Keeping

The Central England Temperature gauge showed the region bound by London, Bristol and Manchester was an average of 11.8 degrees Celsius in April, the warmest since record keeping started in 1659, according to the Met Office.