With temperatures in the high 60s and little wind, the day was perfect for spraying.

Last week, five crews of about 13 people each hit the Groveland Ranger District on Stanislaus National Forest each member armed with a backpack full of purple plant killer.

Their goal over the next month is to knock back deer brush, bear clover and manzanita that might choke out baby trees planted since the 1987 Stanislaus Complex Fire.

"Can you guys just remember something for us? We're not killing brush, we're growing trees," said Neil Foster, the 23-year old crewman in charge of mixing 500-gallon batches of the herbicide Accord with water, purple dye and a additive to help distribute the chemicals. On a productive day, Foster will stir up 1,500 gallons of purple liquid.

The Complex Fire burned about 144,000 acres of the Stanislaus forest and much of that was in the 250,000-acre Groveland Ranger District. The Forest Service began planting Ponderosa pine, incense cedar, sugar pine and Douglas fir seedlings five years ago to replace those lost in the flames.

Now, said Bill Armstrong a 26 year Forest Service veteran, culturist on the Groveland Ranger District and the contracting officer representative for herbicide treatments Forest Service officials are spending $744,114 on 3,701 acres to make sure those trees grow.

That boils down to about $25,000 per day for herbicide chemicals and labor over 30 spraying days.

Accord kills undesired brush by interfering with photosynthesis, Armstrong said. The plants aren't killed immediately, but die over days as they lose their ability to synthesize carbohydrates. This takes competition for water, sunlight and nutrients off the baby trees.

Not all plants are killed, though.

"We avoid oaks. They cannot spray oaks," Armstrong said, noting that the trees are important forest wildlife habitat. Sprayers also watch out for cultural resource sites, avoid other sensitive species, and leave a 10-foot buffer around streams.

To ensure crews apply chemicals under safe conditions and taxpayers get the most from their money, Armstrong said he stays constantly dialed into the weather report.