SALT LAKE CITY (AP) -- A Bureau of Land Management proposal to apply herbicides to nearly 1 million acres in 17 Western states is drawing fire from environmentalists and organic food producers.

Verlin Smith, BLM branch chief for renewable resources in Utah, said the weed killer is needed to combat the rise of cheat grass, tamarisk, Russian olive and other invasive species, which he says are strangling rangelands and wildlife habitat and sucking up precious water resources.

"It changes the whole fire cycle. Normally, fire in a vegetative ecosystem occurs every so-many years. But with cheat grass and other invasive plants, that time frame shortens considerably. It perpetuates the cheat grass and almost wipes out the possibility that the native species will be able to re-emerge and reclaim the site," he said.

"This is an effort to reclaim some of these lands from invasives. Herbicides are one of the tools we have at our disposal," he said.

Much of herbicide application will be from the air.

Smith said in Utah it will occur all over the state, but focus on cheat grass on the grazing lands of the west desert.

The proposal, which is in a public comment period through Jan. 9, has generated opposition from those who fear the unknown consequences of the aerial spraying of herbicides in a wide array of areas, including national monuments and conservation areas.

The Organic Consumers Association has launched a nationwide petition drive to halt the program, which they say includes the use of toxic pesticides, such as 2,4-D, bromacil, chlorsulfuron and others.

"The aerial spraying of herbicides and pesticides to kill weeds is borderline insanity," said Jim McMahon, an ecologist and activist based near St. George. "You're talking about dropping stuff on the ecosystem that will enter the food chain.

"While the intention may be good and they're saying it will be safe, the fact of the matter is we don't know what the long-term ramifications of this will be. Often we find 15 to 20 years after something like this that it was just a bad idea," he said.

BLM officials said they have gone to great lengths to ensure the herbicide program is safe, and the agency has the backing of ranchers and the Legislature in Utah.

"This program has taken a long time to develop, and the reason it has is because the risk assessment took a long time," Smith said. "We spent a long time analyzing the true risk of using herbicides at that level. We can do it, and do it safely so long as we follow the label directions and apply the appropriate mitigation processes. "