PROGRESS IN THE GLOBAL PHASE OUT OF METHYL BROMIDE AND THE RELATIVE EFFECTIVENESS OF SOIL DISINFESTATION STRATEGIES

The Montreal Protocol which regulates ozone depleting gases is the most effective environmental protocol and now has a commitment from all Parties in the world. It has dramatically reduced consumption of the major ozone depleting chemical, methyl bromide (MB), and represents an excellent model for future phaseout of other environmentally damaging products, such as those involved with climate change. Over a fifteen year period, 85% of MB (c. 45,000 t) used for preplant soil fumigation has been phased out and a wide range of chemical and non chemical technologies adopted for disease and weed control in agriculture. In addition to use of alternative fumigants there has been an increased use of substrate systems, grafting and plant resistance for disease control which, in most cases, avoid the need for soil disinfestation. An international metaanalysis has shown that other fumigants, such as 1,3-dichloropropene (1,3 D)/chloropicrin (Pic), metham sodium, iodomethane (MI)/Pic, with or without barrier films are effective and these also have been adopted by growers as alternatives strategies for soil disinfestation with generally equivalent yields to MB. The implementation of these alternatives has led to a 45% fall in bromine in the atmosphere and this is very important to ozone layer recovery. Internationally, pressure is mounting to restrict use of all fumigants worldwide (EC Reg 2037/US Cluster Analysis) and this will further stimulate new technologies for plant disease control. There are also moves to restrict MB, approx. 10,300 tonnes a year, used for quarantine and pre-shipment (QPS). The pressure on fumigant use globally will continue to stimulate development of more sustainable integrated pest management (IPM) strategies that are beneficial to soil health and crop yields.