Volunteers deliver freshly harvested stem mustard at Erdu Village in Fuling District, southwest China's Chongqing Municipality, Feb. 13, 2020. A volunteer service group has been formed in Fuling District of Chongqing Municipality to help locals in need and those who are in quarantine at home to harvest stem mustard, the raw material for the pickle, amid the fight against novel coronavirus outbreak. (Xinhua/Wang Quanchao)

Volunteers deliver freshly harvested stem mustard at Erdu Village in Fuling District, southwest China's Chongqing Municipality, Feb. 13, 2020. A volunteer service group has been formed in Fuling District of Chongqing Municipality to help locals in need and those who are in quarantine at home to harvest stem mustard, the raw material for the pickle, amid the fight against novel coronavirus outbreak. (Xinhua/Wang Quanchao)

A volunteer delivers freshly harvested stem mustard at Erdu Village in Fuling District, southwest China's Chongqing Municipality, Feb. 13, 2020. A volunteer service group has been formed in Fuling District of Chongqing Municipality to help locals in need and those who are in quarantine at home to harvest stem mustard, the raw material for the pickle, amid the fight against novel coronavirus outbreak. (Xinhua/Wang Quanchao)

Volunteers harvest stem mustard for villagers at Erdu Village in Fuling District, southwest China's Chongqing Municipality, Feb. 13, 2020. A volunteer service group has been formed in Fuling District of Chongqing Municipality to help locals in need and those who are in quarantine at home to harvest stem mustard, the raw material for the pickle, amid the fight against novel coronavirus outbreak. (Xinhua/Wang Quanchao)

Volunteers harvest stem mustard for villagers at Erdu Village in Fuling District, southwest China's Chongqing Municipality, Feb. 13, 2020. A volunteer service group has been formed in Fuling District of Chongqing Municipality to help locals in need and those who are in quarantine at home to harvest stem mustard, the raw material for the pickle, amid the fight against novel coronavirus outbreak. (Xinhua/Wang Quanchao)

Volunteers harvest stem mustard for villagers at Erdu Village in Fuling District, southwest China's Chongqing Municipality, Feb. 13, 2020. A volunteer service group has been formed in Fuling District of Chongqing Municipality to help locals in need and those who are in quarantine at home to harvest stem mustard, the raw material for the pickle, amid the fight against novel coronavirus outbreak. (Xinhua/Wang Quanchao)

A volunteer (R) harvests stem mustard for villagers at Erdu Village in Fuling District, southwest China's Chongqing Municipality, Feb. 13, 2020. A volunteer service group has been formed in Fuling District of Chongqing Municipality to help locals in need and those who are in quarantine at home to harvest stem mustard, the raw material for the pickle, amid the fight against novel coronavirus outbreak. (Xinhua/Wang Quanchao)