Agricultural pesticides are causing significant damage to the Great Barrier Reef, according to a new Australian government report on water quality at the site.
The report says some farmers must be more careful with their chemicals.
It found that nearly one-quarter of horticulture producers and 12% of pastoral farmers were using practices deemed unacceptable by the industry.
The Great Barrier Reef is a World Heritage-listed natural wonder.
Sugar cane criticism
In recent years, it has been coral bleaching caused by climate change that has damaged the Great Barrier Reef, but the first Australian government report on water quality there has found that agricultural pesticides are posing significant risks.
Pesticides have been found up to 60km (38 miles) inside the reef at toxic concentrations known to harm coral.
The heavy flooding and a cyclone that ripped through northern Queensland earlier in the year are thought to have made things worse, by flushing pollutants out to sea.
The report said many horticulture producers were using practices considered unacceptable, and that the sugar cane industry in the wet tropics of northern Queensland was particularly to blame.
However, the agriculture industry has said the findings are based on old data, and that there has been a significant change.
The government agrees that farmers have been using more environmentally friendly methods, but says those improvements had been undermined by Cyclone Yasi.
There have been calls from conservationists to limit the use of pesticides and to ban certain weed killers.
But sugar cane producers have argued that there are no alternatives to adequately protect their crops.