 |
Rural Industries Research & Development Corporation |
Rural Industries Research & Development Corporation
|| Home || Search || Contact || Publications Eshop || Privacy Statement ||
Summary of full report
Determining whether pesticide application rates for Culinary Herbs meet MRL requirementsby Neil Treverrow and David Hine
Food safety is a critical issue in market access and responsible and legal use of pesticides is a key issue. Culinary herbs have been produced in volume in Australia for many years and growers have assumed pesticides registered for use on leafy vegetables could legally be used on culinary herbs. The food safety issues and commercial requirements led to inquiries with the National Registration Authority which showed culinary herb growers would not be able to use pesticides unless permits were obtained specifically authorising the uses.
Temporary permits were obtained by the Culinary Herb Growers Working Party (precursor to the Australian Culinary Herb Growers Association Inc.) for ten pesticides for use by culinary herb growers. Further inquiries ascertained five of the pesticides covered by permits already met requirements for MRL compliance. For the remaining five critical residue data was needed to satisfy compliance.
The current project was devised
to ensure culinary herb growers continue to have market access by providing
pesticide residue information required to obtain long term permits for
pesticides considered essential for economic production
The National Registration
Authority guidelines required each pesticide be applied to representative
herbs using sound pesticide application procedures, at the rate indicated
in the relevant temporary permit. After the required withholding period
had elapsed, samples were taken and submitted to a commercial laboratory
for residue analysis by the appropriate method.
Five indicative herbs were selected; Mint, Garlic chives, Dill, Sorell and Rosemary. Collectively they represent a range of leaf sizes, growth habits, leaf waxiness, and content of essential oils. Consumption both as fresh or cooked product was also covered. These herbs were treated with the insecticides alpha cypermethrin, bifenthrin, dimethoate and fipronil; the fungicides benomyl and chlorothalonil, and the herbicide, fluazifop-P-butyl.
Of the insecticides assessed, fipronil produced residues in excess of the temporary MRL and was not considered for a permit application. The residue levels for alpha-cypermethrin, bifenthrin and dimethoate were all well below the specified MRL values and would be suitable for further use on this account.
However alpha-cypermethrin showed some phytotoxicity in all the herb species tested. This was most evident in Mint, where both a slight yellowing and loss of leaf surface gloss made the product temporarily unsaleable.. While this was in evidence in the current trial, other growers have suggested that in their experience, this was anomalous. It is intended to submit a permit for alpha-cypermethrin for the purpose of being part of the regional rotation strategy for insecticides in controlling Diamond back moth in Western Australia.
The four insecticides are all moderately to strongly broad spectrum and should provide for control of a range of insect pests.
Of the fungicides, chlorothalonil was suitable in Dill, Garlic Chives and Mint but caused excessive residues in Rosemary. The high residue levels in Rosemary indicate the behaviour of Rosemary in retaining residues was very different to the others. Some further investigation, possibly using a longer withholding period for this herb, may be needed.
Benomyl residue data were not available due to analytical problems and need to be pursued as soon as possible. An extension of the current temporary permit for benomyl has been sought to allow this data to be pursued.
The one herbicide tested, fluazifop-P butyl, caused no excess residues but exhibited phytotoxicity and its use in herbs is questionable. Fluazifop-P butyl was phytotoxic to some degree in all the herb species tested. It was most phytotoxic in Mint and Dill where total crop loss was experienced. The use of fluazifop-P butyl in herbs might be considered in certain long lived crops such as Rosemary. This is in contrast to annuals of short duration such as Dill where other strategies for weed control are exercised, for example mechanical cultivation or crop and weed destruction by glyphosate before crop establishment.
Long life permits for those pesticides tested which proved suitable have been sought. These should allow growers to address key pest problems.
Further permits will be required.
Development of residue data for benomyl needs to be pursued as a priority.
Some further investigation of residues of chlorothalonil in Rosemary and
similar types of herbs would be desirable. Further investigation of the
phytotoxicity of fluazifop-P-butyl to herbs may be warranted or alternatively
other herbicides potentially suitable for this purpose could be investigated.
 
|
