Managing director Doug Rathbone said the company expected a full-year net profit of $220-230 million.

Nufarm, based in Melbourne, posted a $163.9 million record profit in 2007-08.

"While Brazil — which last year comprised 15pc of group sales — will come in below our original estimates, the balance of the business is in an excellent condition," he told the annual meeting.

"Underlying demand for crop protection products remains strong and we expect to be able to at least maintain profit margins across our various product positions."

Mr Rathbone said the company had improved its glyphosate supplies due to better ties with Monsanto and new partners in China.

"Global demand for glyphosate will … continue to expand, driven by the increased adoption of Roundup Ready cropping systems," he said.

Also, agriculture was being commercialised in developing markets where farm yields were "still to be optimised".

Despite commodity prices falling from historic highs in the past year, Mr Rathbone said key crop prices remained relatively strong and well above their 10-year averages.

Better yields were still needed to meet growing demand from an increasing population.

Mr Rathbone said Nufarm's strengths — its expanding products and wide geographic reach — positioned the company well.

Australia now constituted less than 30pc of group revenue.

"The downside risks to our guidance include the possibility of credit-related pressures," he said.

Other risks as well, are climate conditions and reviews by competition regulators in Britain and the US, of Nufarm's acquisition of herbicide manufacturer A. H. Marks.

Mr Rathbone said Nufarm aimed to reduce its gearing back to the targeted 50-55pc.

Last year gearing moved from 57pc to 69pc.

The company had renegotiated debt, creating longer-term credit lines, and added facilities, which meant the group had just under $1.8 billion available.

Mr Rathbone said he was confident that $200 million due for renewal by next July "will be successfully completed".

"This refinancing has … weighed heavily on the company's share price over the past couple of months," he said.

But continuing support from the bankers showed their confidence in the company, he said.

Nufarm shares closed 95¢, or 12.5pc, higher at $8.50.

They have lost 40pc of their value in the year to date, almost halving in the past two months.