Brazil to harvest entire cane crop this season - Cosan CEO

* Cosan reports first-quarter earnings on Wednesday

* CEO sees south-center crop at 500 mln to 530 mln tns

SAO PAULO Aug 6 (Reuters) - Brazil's center-south sugar cane mills should not have to leave any of the 2012/2013 crop in the fields for processing next season, the head of the country's largest sugar exporter Cosan said on Monday.

Cane mills in Brazil's main sugar-producing region kicked into high gear in early July after rains receded, calming fears that unseasonably wet weather in May and June would result in part of the crop left stranded in the field.

"It's been a much better climate, we're at a very good pace," Cosan's Chief Executive Marcos Lutz told journalists. "There won't be any cane left standing."

Lutz declined to give details on the amount of cane Cosan has collected so far. He spoke two days before the company releases its first-quarter earning results in Brazil, supplier of half the world's sugar exports.

Brazil's cumulative sugar output since the start of crushing in April remains 22 percent behind last year according to milling industry association Unica. But mills churned out nearly a third of the total sweetener produced so far this season in the first two weeks of July.

Lutz said Brazil's center-south region would harvest between 500 million and 530 million tonnes of cane this season, in line with Unica's forecast of 509 million tonnes and above the 494 million tonnes of cane crushed last season.

"This rain, which delayed the harvest, improves the total estimated milling this year... but it worsens the concentration of sucrose," Lutz said. "The final product does not change then, there is more cane, but it is more watered down."