The proposed world-wide ban on methyl bromide has countries across the world searching for economical alternatives.

Of the 160 tons of methyl bromide used in New Zealand during 1996, 56 tons were used for quarantine and preshipment (QPS). Since 1991, New Zealand's methyl bromide use for non-QPS has dropped by 35 percent. Horticultural and agricultural products make up 70 percent of New Zealand's economy.

"New Zealand's horticultural exports are dominated by apples and kiwifruit, with the most important markets being Europe, Southeast Asia, and the United States," says Tom Batchelor. He is co-chair of the Perishables Subcommittee of the United Nations Environment Programme Methyl Bromide Technical Options Committee. This subcommittee deals mainly with quarantine issues.

"Some countries, like Japan, require fumigation of fruit with methyl bromide prior to export to control pests, such as codling moth, that could be present.

"Our economy depends on the survival of our horticultural and agricultural markets, and to do that we need alternatives to methyl bromide. The Market Access Science Group at HortResearch in Auckland has been working since 1985 to find environmentally and economically sustainable treatments for controlling quarantine pests," says Batchelor.

The group's research focuses on investigating the effectiveness of treatments such as heat, cold, controlled atmospheres (CAs), generally-regarded-as-safe (GRAS) compounds, energy treatments, and various combinations of these treatments.

"CAs, like 1.2 percent oxygen and 1 percent carbon dioxide, have the potential to control lightbrown apple moth (Epiphyas postvittana) and wheat bug (Nysius huttoni) on Royal Gala and Granny Smith apples," says Batchelor. "Both are quarantine pests on apple exports to the United States. Royal Gala tolerates the 17- to 20-hour treatment required to control lightbrown apple moth and wheat bug, but Granny Smith does not. Trials are continuing with heat and cold treatments in an effort to select a commercial treatment that controls pests without fruit damage," adds Batchelor.

Registered fumigants/pesticides for soil use in New Zealand include chloropicrin, metam sodium, and dazomet. "Chloropicrin as a soil treatment may become more widely used once the successful results found in Australia are transferred to New Zealand conditions," says Batchelor.

Nonchemical treatments such as natural substrates like composted pine bark, artificial substrates, biological control, and steam treatments are under investigation. "Steam treatment has been adopted in mushroom houses that once relied on methyl bromide for disinfestation,"says Batchelor.

New Zealand is developing systems aimed at reducing quarantine pests through various control measures that originate in the orchard or fields and continue at various points in the production chain—from the orchard to the export market.

"New Zealand is gathering data to demonstrate minimal risks from quarantine pests in the packed carton and developing documentation and systems for critical control points that provide phytosanitary assurance to our overseas trading partners," says Batchelor. He adds, "Interestingly, the security achieved from the systems approach often exceeds that achievable from methyl bromide fumigation."