'AHUIMANU — After years of hunting down bush beardgrass, the O'ahu Invasive Species Committee has recorded a substantial reduction in the weed in Halawa Valley and 'Ahuimanu.

Bush beardgrass is one of many invasive species that the committee has gone after in recent years, and monthly forays into Halawa and 'Ahuimanu subdivisions have resulted in a drop in the number of new sprouts. But despite the improvement, there has been no declaration of victory.

"Of all the plants, grasses are the toughest to deal with because they evolved to move," said Rachel Neville, outreach specialist for the invasive species committee. "I think we have been successful stopping it, especially from getting to the drier parts of the island."

In the dry lands, the grass becomes a fire-promoting agent that can increase the frequency of wildfires, she said.

And despite efforts at Windward sites, volunteers have seen some of the noxious plant on the cliffs behind Valley of the Temples, clinging to slopes too steep for climbing, she said. The committee is trying to figure out a way to reach those plants, Neville said.

Janet Sakagawa, an 'Ahuimanu resident, didn't know that she was nurturing an invasive species when she encouraged bush beardgrass to grow at her home. She thought it was attractive and let the grass spread in one corner of the yard, where it grew bigger and bigger.

One day, committee volunteers knocked on her door, informed her that she was harboring a pest and offered to remove and dispose of the plant properly.

Sakagawa said she was shocked to learn that the plant had taken over areas on Kaua'i and the Big Island and were "past the point of eradication."

They volunteered to dig out her infestation and take it to an incinerator "rather than throwing it in a landfill where it would thrive," she said.

The volunteers promised to return every month to check on her yard and one time found 700 seedlings growing there. Sakagawa said she thinks the seedlings were the result of her yardkeeper using a weed whacker, spreading the seeds everywhere.

The committee volunteers then asked to discuss an alternative, and that is when a crew of four came to her home, applied an herbicide, installed a weed mat and re-landscaped the site at no cost, although she said she did contribute red cinder and more weed mat when they ran out.

"They were very gracious and generous of their time," Sakagawa said.

The grass is gone, but she said she checks regularly and pulls any suspicious plant. She also tries to educate her neighbors who aren't as willing to let the committee come on to their property to remove the grass.

The O'ahu Invasive Species Committee has had better results on other plants, including miconia, smoke bush and fireweed, she said. No mature miconia trees have been spotted, and the smoke bush and fire weed have been eradicated, Neville said.

"We're a little bit nervous about saying eradicate because plants have a way of coming back," she said.

Now the committee has decided to weed out the pampas grass, a popular golf course ornamental with a silvery feathery seed head. It is a problem on Maui, New Zealand, Australia and California, Neville said.

"It hasn't jumped the fence line yet, but we think it's going to, so we're asking people who have it in their yards to let us remove it," she said.

Reach Eloise Aguiar at eaguiar@honoluluadvertiser.com.