(CBS) Some poppy farmers in Afghanistan's biggest opium-producing region have started harvesting this year's crop early in hopes of finishing before the government moves to destroy their narcotic-bearing plants.

"We're in a hurry. We're afraid the government will come and eradicate our fields," village chief Mohammed Agha said Tuesday. His workers are daily slitting the green poppy bulbs and collecting the milky opium resin 10 days ahead of harvest time.

The accelerated efforts of Agha and his laborers signal how difficult it will be for the weak Afghan government to effectively implement a U.N.-backed plan to wipe out Afghanistan's poppy crop, once the source of 70 percent of the world's opium. The narcotic is the raw material used to make heroin.

The plan went into effect Monday, with the government of interim Prime Minister Hamid Karzai offering poor farmers about $500 an acre to destroy their poppies or allow tractors to churn up the fields.

But farmers in southern Helmand province say they need several times that amount to cover their cultivation expenses since late last year, when the Taliban - successful enforcers of a poppy ban - were ousted by a U.S.-led military campaign.

Since Friday, at least nine poppy farmers and one government official have died in three separate confrontations linked to the state eradication plan, according to Afghan officials.

In Lashkar Gah, the dusty capital of Helmand, farmer Abdul Hakim lay in a hospital bed with a bullet wound in his chest. Security forces shot him during a protest Sunday by poppy-growers in Kajaki district, north of the provincial capital.

"People have spent so much money on their crops. They're tired, they work hard. And now the government is trying to eradicate their crops," 34-year-old Hakim said.

He said several thousand farmers had tried to march to the district chief's office to protest the government poppy policy. When soldiers stopped them advancing, they hurled stones that shattered the windows of military vehicles.

Security forces fired in the air, and then on the crowd. Eight farmers died, according to local officials.

"Death to America," Hakim quoted the protesters as shouting. He said they accused the United States of pressuring the Afghan government to institute the poppy ban.

Afghan officials in Kabul, the capital, have acknowledged that the United Nations and foreign governments have urged them to wipe out the poppies, source of much of the heroin available in Europe. American addicts get most of their heroin from Colombia and Mexico.

In Essazai Kili, the bulbs in several poppy plots stand tall on strong stems. The bright flowers of many have fallen away, a sign that harvest time is imminent. Many bulbs are already scarred by the small, metal-edged implements that farmers use to scratch the surface of the bulb.

The village is in a hot, sandy area where the poppy harvest traditionally starts sooner than other places in Helmand.

Agha, the village chief, displayed a metal plate of harvested opium, a brown, gooey mound resembling molasses, with a pungent odor. He said he planned to sell it to a dealer in Lashkar Gah, 8.5 miles to the north.

The opium market in Lashkar Gah has been closed since January, when the government announced the poppy ban. But Agha said the dealers were still in town, only operating out of their homes or other more discreet locations.

Couriers then buy the opium and ferry it across the desert on camels or in pickup trucks, south into Pakistan or west into Iran. Some of it is set aside for local drug abusers, while the rest is processed into heroin and shipped to Europe.

There are well over 100,000 acres of poppies in Afghanistan, according to a preliminary U.N. assessment, indicating the challenge of enforcing a ban on the crop in a country ravaged by more than two decades of war.

The Taliban banned the crop in 2000, but the downfall of the Islamic militia amid a U.S. bombing campaign prompted farmers, who say they don't earn enough from licit crops such as wheat, to quickly replant poppy seeds.

In an interview in his office, Sher Mohammed, the governor of Helmand, said tractors protected by armed guards started destroying poppies on Tuesday. He estimated that the machines had eradicated 100 acres, a tiny fraction of the poppy fields in Helmand.

The governor, who fought the Soviet army during the Russian occupation of Afghanistan in the 1980s, said he was not aware that opium collection had begun in Essazai Kili.

There is an untouched field of poppy flowers just five minutes' drive from the dirt airstrip in Lashkar Gah, where half a dozen British soldiers deployed in the town waited as a C-130 military transport plane bearing supplies landed in a huge cloud of dust.

The main purpose of the troops' presence is to scout around for Taliban or al-Qaida remnants, and they are not involved in the poppy eradication program. They wore civilian clothing, and their faces and hair were caked with dust.

Asked how the situation was in Lashkar Gah, one replied: "Up and down."