Available Alternatives to Methyl Bromide for the Perennial Crop Nursery Industry
California nursery certification regulations have relatively few approved treatment schedules owing to the shortage of products with both sufficient efficacy on the target pests and California registration. Those that are available are generally based on the fumigants methyl bromide (MB) and 1,3-dichloropropene (1,3-D), with some combination treatments including chloropicrin (Pic) or methyl isothiocyanate generators such as metam-sodium. Methyl bromide has long been the most common treatment used to meet certification requirements, and growers are comfortable with field preparation requirements and appreciate the broad spectrum control of both nematodes and other lesser regulated pests such as crown gall and annual and perennial weeds. Although MB use was officially phased out in 2005 owing to negative effects on stratospheric ozone, the fumigant is still allowed in certain crops under annually requested Critical Use Exemptions (CUE) to the Montreal Protocol and under Quarentine/PreShipment (QPS) regulations for nursery stock.