The Costa Rican government has declared a phytosanitary emergency in the north and central Pacific regions of the country, where a camp rat plague known as "Sigmodon hirsutus" has been raging, the Phytosanitary Service of the State said on Tuesday.

The camp rats affect sugar cane, rice, corn and pineapple harvests in the region, and the Costa Rican authorities have issued a decree requesting the collaboration of local farm owners in controlling the plague.

The phytosanitary service said it would take harvest samples to determine the damage, and conduct researches to decide the population of the rats.

Luis Sanchez, chief of the agency's Plague Vigilance and Control Office of the Gunacaste region, said regional organizations and independent producers would also join in the efforts to control the plague.

Experts said that a long drought period in humid regions or pouring rains in drought areas have contributed to the plague by killing many of the rat's less adaptable natural predators.

(Xinhua News Agency August 26, 2009)