Monsanto confirmed this week it had been informed of the situation by the local Cotton Growers' Association, and contacted the growers and worked with them to understand the situation, before determining what action was appropriate in consultation with the grower association.

The planting window for Bollgard II in the Central Highlands was from September 15 to October 31, and was stipulated in the Resistance Management Plan (RMP) for the Emerald region.

A spokesperson for Monsanto said the company had worked closely with scientists including the CSIRO, the cotton industry and Government regulators to develop the RMP as well as working with individual cotton growers to implement the RMP, including the planting window each year in each region.

Cotton growers in each district choose their six-week planting window dates for their district.

Staying within the six-week planting window is crucial to manage the risk that pests can evolve resistance to Bollgard II.

Bollgard II technology provides in-built protection against heliothis, effectively reducing the use of pesticides in cotton crops.

The planting window means that Bollgard II cotton must be planted and watered up within a set time so only a known number of generations of the insect pest will be exposed to the pest control proteins in the cotton.

By limiting the exposure of the pests to Bollgard II proteins, it reduces the risk of resistance developing in the pest population.

"Monsanto, growers, industry organisations and government regulators are very committed to ensuring that GM technology in cotton is well managed and has a long and useful life for growers," a statement from Monsanto said.

"Monsanto has been working with biotech traits with the Australian cotton industry for 12 years with good stewardship results and a lot of value for growers and the environment from GM cotton."