Agrium announced worse-than-expected results, hours before a shareholder vote on its merger plans with PotashCorp.
The Canadian fertilizer company slashed its full year profit expectations, to $4.60 to $5.00 a share, down from a previous forecast of $5.00 to $5.30 a share, after low fertilizer prices hit earnings.
The company warned that the wet weather in Canada would hit ammonia demand over the rest of the year.
Agrium reported a net loss from continuing operations of $39m, or 29 cents per share, in the three months to September 30.
This compares with a net profit of $99m, or 72 cents per share, over the same period last year.
Adjusted losses were 12 cents a share, where analysts forecast earnings of 11 cents a share.
Total sales fell by about 11 percent to $2.25 billion.
"The reduction in net earnings was driven by lower year-over-year nutrient pricing, low pest and disease pressure in the US which limited the demand for crop protection products and application services this growing season," said Agrium chief executive Chuck Magro.
The company also noted a "delayed harvest across North America related to wet weather, and one-time costs primarily related to the proposed merger with PotashCorp".
For the rest of the year, Agrium reported that growers "have experienced poor fall weather in Canada and pockets of the US which has impacted harvest progress and ammonia applications".
Later on Thursday, shareholders of Agrium and its fellow Canadian potash miner PotashCorp will vote on a proposed merger between the companies.
The agreement, signed in September, will see PotashCorp and Agrium join forces, with PotashCorp shareholders taking 52% of the new merged company.
Speaking to investors, Mr Magro said "all indications are that it will be overwhelmingly supportive by both sets of shareholders".
Agrium shares in New York were down 0.8% on the day ahead of the vote, at $90.51.
By William Clarke