Posted on: Thursday, April 28, 2005

Lime added to arsenal in war on coqui

Advertiser Staff

The state Department of Agriculture has received federal permission to use hydrated lime in its battle to control the coqui frog.

The Environmental Protection Agency approved the department's request for an emergency exemption that will allow plant nurseries, property owners and government entities to use the commonly available substance in outdoor nurseries, residential areas, resorts, parks, forest habitats and natural areas.

Citric acid has been the primary weapon against the noisy frogs, but its high cost restricted its use by some business and property owners, officials said. Hydrated lime, or calcium hydroxide, is cheaper and more readily available, and is commonly used by farmers and home gardeners to enrich soil.

Coqui are considered a severe nuisance because of their mating chirps, which are known to reach 90 to 100 decibels, and scientists fear the creatures are competing with native birds for insect prey.

The frogs, which are about the size of a quarter, were inadvertently imported to Hawai'i in nursery shipments. They have established about 300 populations on the Big Island, where there is little hope of eradicating them. The outlook for Maui is nearly as bleak, as coqui persist at resorts and nurseries while gaining a strong foothold in natural areas where control is difficult.

However, there is only one known population of coqui on Kaua'i, on private property at Lawa'i. On O'ahu, a population at Wahiawa is under control, officials said.

The EPA said it was the first time anyone had sought use of hydrated lime for frog control under the emergency program of the Federal Insecticide, Fungicide and Rodenticide Act.

The exemption, which expires in three years, allows treatment using a 97 percent powder formulation of hydrated lime as a dust or in a 3 percent solution for spraying. The Department of Agriculture is required to provide labeling stating that hydrated lime should not be applied to food crops or in areas where children play or congregate. It also should not be used in areas recently treated with ammonium-containing fertilizers, since the fertilizers may react with the lime, releasing ammonia. The label must advise the use of protective clothing and eyewear, chemical-resistant gloves and respirators when applying the substance.

Overexposure to lime may cause eye and skin irritation and inflammation of the respiratory tract.

Anyone wishing to use hydrated lime for coqui control will be required to submit an "applicator authorization form" to the product dealer. Forms are available from dealers and the state Department of Agriculture's pesticides branch. Forms also are available on the department's Web site at www.hawaiiag.org/hdoa/.