Dichlorvos and trichlorfon use in New Zealand horticulture
Park NM, Walker JTS, Shaw PW, Wallis DR July 2009
A report prepared for ERMA New Zealand
Park NM, Walker JTS
Plant & Food Research, Havelock North Shaw PW, Wallis DR
Plant & Food Research, Nelson
PFR SPTS No. 2810
PFR Client Report No: 32498
PFR Contract No: 23614
DISCLAIMER
Unless agreed otherwise, The New Zealand Institute for Plant & Food Research Limited does not give any prediction, warranty or assurance in relation to the accuracy of or fitness for any particular use or application of, any information or scientific or other result contained in this report. Neither Plant & Food Research nor any of its employees shall be liable for any cost (including legal costs), claim, liability, loss, damage, injury or the like, which may be suffered or incurred as a direct or indirect result of the reliance by any person on any information contained in this report.
This report has been prepared by The New Zealand Institute for Plant and Food Research Ltd (Plant & Food Research), which has its Head Office at 120 Mt Albert Rd, Mt Albert, AUCKLAND. This report has been approved by:
Nicola Park
Research Scientist/Researcher Date: 31 July 2009
Philippa Stevens
Group Leader, Bioprotection Date: 31 July 2009
Contents
Page
Executive Summary... 1
Introduction ... 2
Methods ... 2
Sources of Information for the ‘Trends in Pesticide Use in New Zealand: 2004’ Report ... 2
Dichlorvos and Trichlorfon Products Currently Registered in New Zealand for Horticulture ... 3
Maximum Residue Levels on New Zealand Crops ... 7
Quarantine Requirements for Export Crops... 9
Pesticide Resistance Management ... 10
Assessment of Control Options... 11
Results and Discussion ... 12
Persimmons... 12
Passionfruit... 14
Tamarillos ... 15
Berryfruits ... 17
Ornamentals and Cut Flower Production ... 17
Glasshouse Vegetable Production ... 18
Mushrooms... 18
Field Vegetables... 19
Asparagus ... 19
Pasture and Cereals... 20
Clover Seed and Vegetable Seed Production... 20
Turf ... 20
Fruit fly Surveillance Programme ... 21
Conclusions and Recommendations ... 22
References ... 26
Acknowledgements ... 28
Appendices ... 29
Appendix 1. Insecticide use in horticulture... 29
Appendix 2. CODEX Maximum Residue Level (MRL) 2009 for dichlorvos and trichlorfon... 30
Appendix 3. Summary of product application methods, label rates and use ... 31
Executive Summary
Dichlorvos and trichlorfon use in New Zealand horticulture Report to ERMA New Zealand
Park NM, Walker JTS, Shaw PW, Wallis DR. July 2009 ERMA New Zealand (Environmental Risk Management Authority) may perform reassessments on substances for which there is evidence that the risks may not be
adequately managed by existing controls. The information in this report will be available for inclusion in the ERMA New Zealand reassessment application of dichlorvos (CAS number 62-73-7) and trichlorfon (CAS number 52-68-6) being prepared by ERMA New Zealand for public consultation.
Potential user sectors of dichlorvos and trichlorfon were identified from product label registrations and results of the survey reported in Trends in Pesticide use in New Zealand (2004). Scientific and technical experts working on each of the crops were contacted to assess current use patterns, alternative pest control methods and any other crops to which dichlorvos or trichlorfon might be applied. A national literature search was used to assist in identifying and validating issues and likely solutions.
Trichlorfon (sold as TrifonTM) is a broad-spectrum organophosphate that is registered for use on a range of field crops and pasture. Little TrifonTM is used in New Zealand with only some minor use for the control of porina in Southland pasture and possibly in turf management.
As a result of its low level of use, it is likely TrifonTM will be voluntarily withdrawn from market.
Dichlorvos is an inexpensive but effective broad-spectrum organophosphate insecticide registered for use on a wide range of horticultural crops in New Zealand. The main
horticultural sectors currently using dichlorvos are cut flowers particularly orchid production, glasshouse vegetables, field vegetables, persimmon, tamarillo, passionfruit, berryfruit, postharvest fumigation of asparagus and it is used in fruit fly surveillance traps. However, there is also occasional use on other crops, such as vegetable seed production and ornamentals, and potential use in grain and food storage silos and warehouses.
Dichlorvos has superior efficacy across a wide range of pests, proven cost effectiveness, excellent penetration (semi-fumigant action) and rapid knockdown. Its short residual effect means it can be used close to harvest, while its broad-spectrum activity provides a useful option when growers are faced with new pests or unexpected or late season pest build-ups.
These properties also make it ideal for pre-harvest and postharvest disinfestation where needed to meet quarantine regulations. The unique properties associated with dichlorvos means most of its uses are for specific purposes for which there are few if any alternatives.
For further information please contact:
Nicola Park or Jim Walker
The New Zealand Institute for Plant & Food Research Ltd Plant & Food Research Hawke’s Bay
Private Bag 1401 Havelock North Hastings 4157 NEW ZEALAND Tel: +64-6-975 8880 Fax: +64-6-975 8881
Email Nicola.Park@plantandfood.co.nz Email Jim.Walker@plantandfood.co.nz
Introduction
ERMA New Zealand (Environmental Risk Management Authority) may perform reassessments on substances for which there is evidence that the risks may not be adequately managed by the existing controls. In September 2008, a Committee of the Authority decided there were grounds for the reassessment of dichlorvos and its
formulations and trichlorfos and its formulations (ERMA NZ 2008). The information in this report will be available for inclusion in the ERMA New Zealand reassessment application.
Methods
In 2004, a survey was undertaken to provide up-to-date data on pesticide use in New Zealand: outcomes were reported in Trends in Pesticide Use in New Zealand: 2004 (Manktelow et al. 2005). ERMA New Zealand contacted some authors of the pesticide trends report to undertake an assessment of the current use of dichlorvos and trichlorfon in horticulture. The scope was to identify which horticulture sectors currently use dichlorvos and trichlorfon, what were the likely impacts on pest management for those sectors if these agrichemicals were no longer available, and to identify if there were other pest control options for these sectors to replace dichlorvos and trichlorfon.
To identify which sectors were using dichlorvos and trichlorfon, a list was drawn up of sectors that were identified as dichlorvos and trichlorfon users in the Manktelow et al. (2005) report and of crops that were covered by the label claims of products registered for use in New Zealand containing the active ingredients dichlorvos or trichlorfon. Scientific and technical experts working on each of the crops were contacted to assess current use patterns for dichlorvos and trichlorfon and to identify alternative pest control methods. They were also asked if they knew of any other crops to which dichlorvos and trichlorfon might be applied. A national and international literature search was used to assist in identifying and validating issues and likely solutions.
Sources of Information for the ‘Trends in Pesticide Use in New Zealand: 2004’ Report
The New Zealand Association for Animal Health and Crop Protection (AGCARM) was the principal source of information for the national sales data presented in the ‘Trends in Pesticide Use in New Zealand: 2004’ report. Participants in the AGCARM survey provided voluntary annual data on sales of pesticides by kilograms of active ingredient (a.i.), with data grouped into various categories (Manktelow et al. 2005).
While the AGCARM data represented the most comprehensive survey of pesticide sales in New Zealand, the data did not allow specific uses to be determined. Specific use patterns were obtained directly from sectors where possible, but there were some significant uses that could not be covered because of inability to collect data. Key omissions relating to pesticide use were in urban and recreational areas and for minor crops, where few if any pesticides have label claims and crop-specific data were generally not available.
Unfortunately, the pesticide classification system used by AGCARM differs from the Food and Agricultural Organisation (FAO) grouping, which means the data are not consistent with international reporting. Other sources of national pesticide use included a summary of sales values compiled by a market analysis company AC Nielsen Ltd (a survey discontinued in 2002) and Statistics New Zealand, which collects data on quantities of pesticide imported from New Zealand Customs Service records, noting that these data do not include New Zealand-manufactured product (Manktelow et al. 2005).
To address some of the inconsistencies and omissions in the available national pesticide use data, information was also gathered on the quantities of pesticides (insecticides,
fungicides, herbicides and plant growth regulators) used in 69 sectors within the horticultural, arable, forestry and pastoral industries. The data were collected through various means including industry spray diary databases, published information and personal
communications from either scientists/consultants closely involved with a sector, or sector contacts. Pesticide use in the different sectors was then estimated relative to the known land areas of each sector. Estimates for insecticide use in New Zealand are shown in Appendix 1 (Manktelow et al. 2005).
Of the data sources used in the ‘Trends in Pesticide Use in New Zealand: 2004’ report, only the data from the sectors grouped the data down to an active ingredient (a.i) level. From the pesticide use estimates of the sectors in 2004, six sector groups were identified as users of dichlorvos. These sectors were blueberry, tamarillo, passionfruit, persimmon, asparagus and nerines/peonies/Sandersonia (Table 1). No use of trichlorfon was reported (Manktelow et al. 2005).
Table 1. 2004 sector-based dichlorvos use estimates in New Zealand (Manktelow et al. 2005).
Sector
Area (total national ha)
Low use total tonnes a.i/year (national)
High use total tonnes a.i/year (national)
Asparagus 2015 0.02 0.02
Blueberries 430 0.17 0.17
Nerines/Paeonies/
Sandersonia 50 0.01 0.01
Passionfruit 70 0.07 0.42
Persimmons 282 0.32 1.29
Tamarillos 270 0.54 2.16
Dichlorvos and Trichlorfon Products Currently Registered in New Zealand for Horticulture
There are four products containing the active ingredient dichlorvos and one product containing trichlorfon currently registered in New Zealand shown on the New Zealand and Food Safety Authority Agricultural Compounds and Veterinary Medicines (ACVM) Database (NZFSA 2009). Dichlorvos is a volatile organophosphate insecticide and trichlorfon is also an organophosphate insecticide. The product names and registration details are listed in Table 2. The active ingredient content, formulation type and approximate retail price of each of the products are listed in Table 3. Typical use patterns and application methods are summarised in Appendix 3.
Table 2. Registered products in New Zealand containing dichlorvos or trichlorfon (NZFSA 2009).
Product Name
Registration Number
Active
Ingredient Registrant Registration Date
NuvosTM P001132 dichlorvos Orion Crop Protection Ltd 14 March 1968 Divap® P006080 dichlorvos United Phosphorous Ltd.
Distributed by Adria New Zealand Ltd
7 June 2002
ArmourCrop- Insecticide (DDVP)
P005877 dichlorvos BOC Limited 31 January
2002
DDVP Insecticide Strip
P007362 dichlorvos Biosecurity New Zealand.
Manufactured by
Agrisense-BCS Ltd, United Kingdom
12 October 2005
TrifonTM P004686 trichlorfon Tapuae Partnership.
Manufactured by Zelam Ltd (formerly Taranaki NuChem Limited) New Zealand
1 June 1994
Table 3. Active ingredient content, formulation type and retail cost of dichlorvos and trichlorfon products (NZFSA 2009 and product labels).
Product Name Active Ingredient
Active Ingredient Content
Formulation Type
Container
Size Retail Price
NuvosTM dichlorvos 1000 g/litre
emulsifiable concentrate
1 litre 5 litre
$75.79 + GST
$309.10 + GST Divap® dichlorvos 1140
g/litre
emulsifiable concentrate
5 litre $250 + GST
ArmourCrop- Insecticide (DDVP) Insectigas®
dichlorvos 50 g/kg aerosol 7 kg and 35 kg net
7kg $187.49 + GST
$19.20 + GST cylinder deposit Handgun
$529.98 + GST to purchase Handgun $55.72 + GST per month DDVP
Insecticide Strip
dichlorvos 188 g/kg vapour releasing strip
5 strips each 2.6 g
Not available for retail sale.
TrifonTM trichlorfon 500 g/litre emulsifiable concentrate
5 litre $110 + GST
Dichlorvos and trichlorfon crop registrations and product rates
The products containing dichlorvos and trichlorfon registered for use in New Zealand horticulture are registered for use on a wide range of crops and insect pests, the details of which are shown in Table 4 for ArmourCrop-Insecticide (DDVP), Insectigas® and DDVP Insecticide Strips, Table 5 for NuvosTM and Divap®, and Table 6 for TrifonTM. Dichlorvos also has public health uses for the indoor and outdoor control of pests such as flies, cockroaches, ants and food storage pests such as flour beetles and grain weevils. However, this report will focus on the horticultural uses of dichlorvos only.
According to their product labels, all trichlorfon and dichlorvos products must be tracked and must be under the control of a registered Approved Handler as specified in the Hazardous Substances and New Organisms Act 2001. An Approved Handler is a person who is competent and certified to handle hazardous substances and who is aware of their legal obligations with respect to the purchase, transport, safe use, storage and appropriate disposal agrichemicals (ERMA NZ 2004).
Table 4. ArmourCrop-Insecticide (DDVP) and DDVP Insecticide Strip crop registrations and product rates (NZFSA 2009, BOC 2007, BOC 2009).
Product
Horticultural Crop
Recommended Use
Insect Pest Product Rate and application method
ArmourCrop- Insecticide (DDVP)
Greenhouse Capsicum
Aphids 2.5 g/m2 of greenhouse volume applied as a fog through a dose system designed and built by BOC Ltd for each greenhouse Insectigas® Stored product
facilities (e.g.
warehouses, silos, farm machinery and storage bins)
Stored products moths and flour beetles, flying and crawling insects
70 second spray (200 g) into air space
Insectigas® Greenhouse Aphids, spider mites, whiteflies, thrips and caterpillars
200 g spray into air space.
Portable cylinders connected to fixed pipework in
greenhouse or fumigation chamber, connected to hand held spray guns or a release timer on top of the cylinder.
No mixing of concentrate required.
DDVP Insecticide Strip
Fruit fly surveillance programme
For use only by approved operators for the fruit fly surveillance programme
One 2.6-g strip in the base of purpose-designed fruit fly trap
Table 5. NuvosTM and Divap® crop registrations (Novachem 2009 and NZFSA 2009).
Horticultural
Crop Regn Insect Pest
Product Rates for Nuvos
Product Rates for Divap
Water Rates from Product Label
Clover seed crops
Clover case bearer moths
150-220 ml/ha 130-190 ml/ha 110-170 litres water
Brassica Aphids, caterpillars
350-750 ml/ha 300-650 ml/ha 220-450 litres water/ha Cereals Aphids,
caterpillars
350-750 ml/ha 300-650 ml/ha 220-450 litres water/ha Vegetables Aphids,
caterpillars, mites
500-800 ml/ha or
60 ml/100 litres
440-700 ml/ha or
50 ml/100 litres
Boom spray: 220- 240 litres water/ha Mist blower: 60 litres water/ha Handgun: apply to runoff
Tamarillo Aphids, caterpillar, whitefly
100 ml/100 litres
90 ml/100 litres
Not stated
Passionfruit Aphids, caterpillar, whitefly
100 ml/100 litres
90 ml/100 litres
Not stated
Persimmon Caterpillars Latania scale
100 ml/100 litres
90 ml/100 litres
Not stated
Berryfruit Aphids, caterpillars, mites
500-800 ml/ha or
60 ml/100 litres
440-700 ml/ha or
50 ml/100 litres
Boom spray: 220- 240 litres water/ha Mist blower: 60 litres water/ha Handgun: apply to runoff
Ornamentals Aphids, caterpillars, mites
500-800 ml/ha or
60 ml/100 litres
440-700 ml/ha or
50 ml/100 litres
Boom spray: 220- 240 litres water/ha Mist blower: 60 litres water/ha Handgun: apply to runoff
Glasshouses Aphids, mites, whiteflies, thrips, phorid & scarid flies, caterpillars
5 ml/litre/100 metres3 or 25 ml/ 5 litres
4 ml/litre/100 metres3 or 20 ml/ 5 litres
Apply as a fog
Mushroom houses
Aphids, mites, whiteflies, thrips, phorid & scarid flies, caterpillars
5 ml/litre/100 metres3 or 25 ml/ 5 litres
4 ml/litre/100 metres3 or 20 ml/ 5 litres
Apply as a fog
Table 6. TrifonTM crop registration and product rates (Novachem 2009 and NZFSA 2009).
Horticultural Crop
Registration
Insect Pest Product Rates
Pasture Army caterpillar Porina
1.8 – 2.4 litres/ha for Army Caterpillar 2.1 – 2.4 litres/ha for Porina
Grass Seed Army caterpillar 1.8 – 2.4 litres/ha Cereal Army caterpillar 1.8 – 2.4 litres/ha Crops Army caterpillar 1.8 – 2.4 litres/ha Maize Corn earworm 1.8 – 2.4 litres/ha Sweetcorn Corn earworm 1.8 – 2.4 litres/ha
Brassica
Cutworm Diamond-back Moth
White Butterfly
2.4 – 3.6 litres/ha for Cutworm
1.8 – 2.4 litres/ha for Diamond-back Moth and White Butterfly
Tomatoes
Cutworm
Green Vegetable Bug
Tomato Fruit Worm
2.4 – 3.6 litres/ha
Beans Green Vegetable
Bug 2.4 – 3.6 litres/ha
While outside the scope of this report, it is noted that there may be a renewed interest in the only other trichlorfon registered product in New Zealand, Neguvon® 98%. Neguvon® is a veterinary product registered for the control of mites on chickens and pigs. Malathion 50EC has been used for the control of mites on chickens; however, because of the recent
voluntary withdrawal of Malathion from the New Zealand market, there may be some interest in using Neguvon® as an alternate (pers. comm.)
Maximum Residue Levels on New Zealand Crops
Maximum Residue Limits (MRLs) for pesticides are established in most countries to safeguard consumer health and to promote Good Agricultural Practice (GAP) in the use of agricultural compounds. MRLs vary from country to country depending on the pesticides available, the crops being treated and the way the pesticides are used. Food producers must comply with the MRLs of the countries they export to as a condition of market access
(NZFSA 2008).
The New Zealand (Maximum Residue Limits of Agricultural Compounds) Food Standards 2008 are set by the NZFSA. Schedule 1 of the standard sets the maximum residue limits (MRL) of agricultural compounds that are permitted in New Zealand food. If the compound is not specified in the schedule, or not specified in relation to the food type or class in question, residues must not exceed a default value of 0.1 mg/kg. Imported food must also comply with the standard or contain residues of agricultural compounds no greater than the MRLs specified for that food in the current edition of the FAO/WHO Codex Alimentarius
Commission publication Pesticide Residues in Food (NZFSA 2008). The Codex
Alimentarius Commission was created in 1963 by FAO and the World Health Organisation (WHO) to develop food standards, guidelines and related texts such as codes of practice under the Joint FAO/WHO Food Standards Programme (CODEX 2009). There are no CODEX MRLs set for trichlorfon and for horticultural crops there are CODEX MRLs only set for cereals and grains and mushrooms (Appendix 2).
To ensure MRLs are met, withholding periods are listed on product labels. A withholding period (also known as pre-harvest interval) is the time required between the final application of that product and harvest, to ensure spray residues will have decayed sufficiently to enable MRLs to be met. This period is usually expressed as days from harvest, or can be a set date or crop growth stage in the season, and often varies between crops. Export crop pre- harvest intervals often differ from New Zealand pre-harvest intervals, as the export crop must meet importing country and final customer MRL standards.
New Zealand dichlorvos MRLs are specified for fruits, vegetables, cereals and grains with these designations shown in Table 7. There are no MRLs for clover seed crops,
ornamentals or flower production as these are not food crops, but as for all crops there is a re-entry period. There are no MRLs set in New Zealand for trichlorfon with the exception of milk (0.05 mg/kg) and sugarbeet (0.05 mg/kg); therefore, trichlorfon residues must not exceed the default of 0.1 mg/kg for all other crops.
Table 7. Dichlorvos maximum residue limits (MRLs) and pre-harvest intervals in New Zealand and corresponding CODEX MRLs for the same crops.
Crop
New Zealand MRL (mg/kg)
(NZFSA 2008)
CODEX MRL (mg/kg) (CODEX 2009)
New Zealand Pre- Harvest Intervals (NOVACHEM 2009)
Clover seed
crops Not applicable1 Not applicable1
Brassica Vegetables - 2 3 days
Cereals Cereals & grains - 2 Cereals & grains - 5 3 days Vegetables
(except asparagus)
Vegetables - 2 3 days
Asparagus Vegetables - 2 1 day
Tamarillo Fruits - 2 7 days
Passionfruit Fruits - 2 7 days
Persimmon Fruits - 2 2 days
Strawberry Fruits - 2 2 days
Berryfruit (except strawberry)
Fruits - 2 3 days
Ornamentals Not applicable1 Not applicable1
Glasshouse
vegetables Vegetables - 2 3 days
Glasshouse
flowers Not applicable1 Not applicable1
Mushrooms Vegetables - 2 Mushroom – 0.5 3 days
Greenhouse
Capsicum Vegetables - 2 3 days
1Not applicable as not a food crop
MRLs and corresponding pre-harvest intervals must be considered when assessing
alternative chemical control options. To be most effective, chemical applications need to be timed to correlate with the pest phenology and developmental stage. Alternate products must be available for use during this same period.
Quarantine Requirements for Export Crops
MAF Biosecurity New Zealand is the division of Ministry of Agriculture and Forestry (MAF) charged with leadership of the New Zealand biosecurity system. It encompasses facilitating international trade, protecting the health of New Zealanders and ensuring the welfare of our environment, flora and fauna, marine life and Maori resources. An importing country’s phytosanitary requirements (ICPR) standard is a MAF Biosecurity Authority document that specifies an importing country's phytosanitary requirements (MAF Biosecurity New Zealand 2009).
Pesticide Resistance Management
The resistance of pests to pesticides is where the pest population has changed genetically so that it is less susceptible or sensitive to a pesticide or class of pesticides. This means a higher dose of that pesticide is now required to kill all individuals of the pest population or that the highest practical dose will not kill all the pests (Martin et al. (eds) 2005).
Prevention and management of insecticide and miticide resistance is based on two principles:
Preventing resistance to pesticides is a much better approach than trying to manage resistance once control failures occur
If the insect or mite population is not exposed to the pesticide, the proportion of resistance within a population will decline to a level where at least one application of pesticide per season will give control of the pest (Martin et al. (eds) 2005).
The key components of insecticide and miticide resistance prevention and management strategies are:
Maximise use of non-pesticide controls
Only apply pesticides when their use can be justified
Time pesticide applications for when they are most effective and target applications to the specific parts of the crop where they will be most effective
Use good application technique and apply when environmental conditions are favourable Use only one member of a chemical group of pesticides no more than the specified
maximum number of times per year or growing season
Rotate chemical groups of pesticides (Martin et al. (eds) 2005).
Pesticide resistance prevention and management strategies (insecticide and miticide) for New Zealand crops have been developed for these ‘at risk’ individual pest species:
Diamond back moth Tomato fruitworm Spider mite Leafroller Thrips Whitefly Melon aphid Green peach aphid Lettuce aphid Leafhopper Mealybug
The details of these individual strategies are discussed, where relevant, in the context of each crop.
Non-chemical control techniques
Non-chemical control options include:
Quarantine (keeping the pest off the property and out of the country) Plant resistance
Agronomic and cultural techniques
Biological control and methods to enhance biological control e.g. use of predator insects, insect specific viruses
pheromone mating disruption (Martin et al. (eds) 2005).
Assessment of Control Options
There are a number of factors that were considered when assessing dichlorvos and trichlorfon current use and alternative pest control options. These were:
Products already registered in New Zealand for that crop
Products already registered for use in New Zealand for control of that pest Products allowed by export industries
Maximum Residue Limits (MRLs) in New Zealand and key export markets Quarantine requirements for export crops
Non-chemical (cultural) control options
Agrichemical Resistance Management Guidelines
Compatibility with integrated pest management principles, which gives preference to pest-specific chemistry such as insect growth regulators and other selective insecticides that are not toxic or disruptive to beneficial insects.
Results and Discussion
Persimmons
The New Zealand persimmon industry comprises approximately 88 growers, which accounts for a planted production area of 180 hectares. The 2008 crop volume was 3,000 tonne valued at NZ$1 million on the domestic market and NZ$0.5 million export value (Plant &
Food Research 2008). The main growing regions are Auckland/Northland and Gisborne.
The key harvest period is April to June (MAF 2006). The New Zealand persimmon crop is almost entirely exported, with the principal market being Asia (Persimmon Industry Council 2001).
Industry programme
In the 1980s, persimmon industry leaders recognised that a calendar spraying approach to managing pests was not sustainable. Using Integrated Pest Management (IPM) principles and with funding assistance for research and programme development from AGMARDT and the Ministry for the Environment, an IPM system and manual was developed for persimmon growers (Persimmon Industry Council 2001).
IPM involves the use of chemical, biological and cultural practices to manage pests, therefore not relying solely on one method of control, and where possible using chemicals that only target specific pests, enabling beneficial insects to contribute to pest control.
The Green & Gold® IPM system aims to enable persimmon growers to:
Produce crops with minimal pesticide residues while still meeting market phytosanitary requirements
Meet customer requirements for environmentally responsible production (Persimmon Industry Council 2001).
Pest control
There have been a wide range of insects and mites recorded on persimmon in New Zealand.
These insects can be categorised as major pests (damaging fruit), minor pests (indirect damage by weakening trees therefore reducing yields), and passenger pests (contaminating fruit). Any of these three categories of pest has the potential to cause serious biosecurity problems if found on export fruit.
The major pests of persimmon are:
Mealybugs – most commonly the longtailed mealybug (Pseudococcus longispinus) Leafroller – most commonly the brown-headed leafroller (Ctenopseustis obliquana) in
Gisborne and the lightbrown apple moth (Epiphyas postvittana) elsewhere Stathmopoda species – garden featherfoot (Stathmopoda skelloni)
Armoured scales – the most serious is latania scale (Hemiberlesia lataniae) Greenhouse thrips – Heliothrips haemorrhoidalis
Tydeid mites – Orthotydeus californicus and O. caudatus Persimmon bud mite – Aceria diospyri.
Passenger pests include thrips (Nesothrips propinquus), oribatid mites, psocids (also known as booklice), spiders and slaters. There are also a number of minor pests (Persimmon Industry Council 2001).
Adequate late season pest control has been an ongoing problem since persimmon exports from New Zealand started. Research by Prestidge et al. (1989) described one of the major production barriers limiting exports as pre-harvest insect contamination of fruit. As the fruit grows, the sepal flattens, effectively forming an umbrella that can cover and protect pests.
Insects and mites hide under fruit sepals and in calyx cracks, creating a quarantine problem to importing countries. Residue tests completed in the late 1980s meant dichlorvos became the preferred agrichemical pre-harvest, as it was virtually non-residual, with residues declining below 0.01 mg/kg in 4 days (Prestidge et al. 1989). Earlier research by Steven &
Sale (1985) highlighted the same issues. The incidence of “passenger” mites (oribatid or tydeid) was high. They were not controlled by chlorpyrifos, diazinon or carbaryl and were difficult to eliminate with postharvest fumigation (Steven & Sale 1985). Synthetic pyrethroids and pyrethrum are alternatives that have been tried but are not very effective (D Steven, pers. comm.).
The persimmon industry currently relies on Attack® (active ingredients permethrin and pirimiphos-methyl) (28%) and chlorpyrifos (20%), which together account for nearly 50% of all insecticide applications. Withdrawal of Attack® from the New Zealand Kiwifruit Crop Protection Programme is likely to result in Attack® being voluntarily withdrawn from sale in New Zealand because of lack of sales (MAF 2009).
The persimmon industry Green & Gold® IPM system became available to growers in 2001.
In 2007, a commercial evaluation of the Green & Gold persimmon crop protection programme was made in Gisborne, funded by the Ministry for Agriculture and Fisheries (MAF) Sustainable Farming Fund. The main findings were that the programme was unable to achieve pest control comparable with conventional blocks. Key pests such as leafroller and mealybug should be able to be controlled by more selective insecticides, but there were a concerning number of contaminants (e.g. spiders, booklice and woodlice) on conventional and IPM programme fruit, which created a quarantine issue for export fruit (MAF 2009).
Dichlorvos use and alternatives
The Green & Gold® Manual lists the control options for each pest. Dichlorvos is
recommended as a pre-harvest ‘clean-up’ spray for the control of all pests and passenger pests. Depending on the length of the harvest period, more than one spray may be required.
Product label rates are followed. Persimmons are not an easy crop to spray and spray coverage is critical to obtain good control. Applications are with an air-blast sprayer using high volume spraying with water rates at 1500 to 2000 litres per hectare, with the higher rates at full canopy (Persimmon Industry Council 2001).
Good orchard hygiene will reduce possible sources of pests including passenger pests.
These cultural practices include reducing neighbouring known plant hosts, keeping shelter belts trimmed, and preventing weeds from growing up into the persimmon trees and keeping a grass-dominated mown sward in the orchard. In addition, sticky bands on tree trucks will assist in preventing pests moving up into the tree canopy, and removing lichens by water blasting the trees will also discourage passenger pests. However, while all these practices should be followed as good orchard practice with an aim of preventing significant pest infestations from establishing, good hygiene alone will only contribute to minimal reductions in spraying (Persimmon Industry Council 2001).
Postharvest disinfestation methods are expensive and there are fruit damage risks Cold treatment disinfestation together with modified atmosphere (low oxygen, high carbon dioxide) treatments have shown that cold rather than gas atmosphere was the key component contributing to successful lightbrown apple moth larvae mortality. Mealybugs were more sensitive to cold than leafrollers. Ideally, temperatures of 0.8-10C are required for 6-8 weeks to achieve mortality. The risk of fruit phytotoxicity (fruit damage) increases beyond this coolstorage interval. Most commercial coolstores operate at higher temperatures of approximately 1 - 20C. In addition, an extended period of on shore coolstorage will be
required as seafreight, which is the main method of shipment to the important Australian market, only takes approximately two weeks.Extended coolstorage incurs extra costs (A Woolf, I Turk, pers. comm.)
Hot water treatment has also been tested for disinfestation of insects and mites on persimmons. Treatment at a water temperature of 51°C for 20 minutes is effective against leafrollers and mealybugs. This method requires expensive equipment and operating costs and there is a risk that a proportion of fruit (5-10%) will be damaged through skin cracking (A Woolf, pers. comm.).
In conclusion, the registration and use of more selective insecticides will control key pests such as leafroller and mealybugs. Dichlorvos is not used or required to control these pests.
However, dichlorvos is used extensively pre-harvest for the control of passenger pests such as oribatid mites. It has a short pre-harvest interval, enabling it to be used close to harvest as a cleanup spray. It is effective against a wide range of insects and its fumigant activity provides control into calyx cracks and under sepals that cannot be achieved through the use of other chemical formulations and spray techniques. With 90% of the persimmon crop exported, it is important these passenger pests are controlled, given the strict quarantine requirements of some markets. Postharvest treatments such as extended coolstorage, modified atmosphere and hot water treatment are not economically viable options, do not fit with current fruit transport and handling systems, and there are fruit damage risks. There are no current alternatives that are effective in controlling this range of pests and that have the unique mode of action provided by dichlorvos.
Passionfruit
The New Zealand passionfruit crop accounts for a production area of 47 hectares, which produced 240 tonnes of crop, valued at NZ$0.6 million in export earnings in 2007
(HortResearch 2007). The main growing regions are Bay of Plenty, Taranaki and Northland and the harvest period is from February to May (MAF 2006).
The crop is sprayed with a knapsack or framework sprayer (not airblast as the fruit are delicate and easily knocked off the vines) at water rates of 1000 l/ha. There is low pest pressure. The key pests are Fuller’s rose weevil, which feed on the growing tips, chewing insects at the start of the season, and thrips, which get under the skin causing ‘pimpling’ on the skin surface (K Sandom, pers. comm.). Thrips damage tends to escalate from late December, resulting in a downgrading of the crop from export grade. Thrips are not a problem every year but are more prevalent in a hot dry season; therefore, an insecticide is not always required for thrip control. When thrips are present, a dichlorvos application is made at label rates, followed by a second application seven to 10 days later. Some growers make additional applications for control of other insect pests with use patterns varying between seasons (various growers’ feedback).
Dichlorvos and diazinon are the only two insecticides specifically registered for use on passionfruit (Table 8). Until recently, the industry also used maldison (Malathion 50 EC), for which MRLs exist in the USA but in June 2009 this product was voluntarily withdrawn from the New Zealand market by the distributor Nufarm Ltd. The main export market is USA.
There is no MRL for diazinon or dichlorvos into this market; however, because of its short residual effect dichlorvos is the only insecticide currently available for thrip control for passionfruit for the USA market (various growers’ feedback).
Table 9 lists spinosad as one potential insecticide that will control thrips. There is an MRL set for spinosad on passionfruit in the USA; however, spinosad is not registered for use on passionfruit in New Zealand.
Passionfruit is a minor crop, whose growers are unable to fund the necessary trials to provide efficacy, crop safety and residue data to support a label claim for spinosad or any other potential alternative. Before de-registering dichlorvos, consideration must be given to identifying a pathway to provide the required efficacy, crop safety and residue data to support a label claim, and sufficient time to develop the technical knowledge and funding to enable the identification and development of alternative control measures.
Table 8. Insecticides registered for use on passionfruit in New Zealand (Novachem 2009).
Chemical Group Active Ingredient
Registered Products Target Pest
Organophosphate diazinon DewTM 600, Diazinon 50W, Diazinon EC, Diazinon 800, Diazinon 800 EC, Diazonyl® 60EC, DigrubTM, Hortcare Diazinon 500EW
Aphids, caterpillars, whitefly, grass grub beetle
Organophosphate dichlorvos Nuvos®, DivapTM Aphids, caterpillars, whitefly
Table 9. Potential alternative active ingredients to dichlorvos for thrips control but not registered or trialled on passionfruit.
Chemical Group Active Ingredient
Product1 Current Registration in New Zealand1
and points of interest
Macrocyclic
lactone Spinosad
Success® Naturalyte®, Yates Success® Naturalyte®
Registered on summerfruit for leafroller, thrips and cherry slug. MRL registered in the USA for passionfruit
1Novachem 2009
MRL = maximum residue limit
Tamarillos
The commercial tamarillo industry comprises 175 growers, with a planted area of 194ha. The 740-tonne crop has a domestic sales value of NZ$1.4 million and export value of NZ$1.1 million (Plant & Food Research 2008). The main growing areas are Northland, Auckland, Bay of Plenty, Gisborne, Taranaki with smaller plantings in Levin, Nelson and Karamea: the key harvest period is June to August (MAF 2006, Watson 2009).
The main export market is Australia. However, this market was closed to tamarillo and all other solanaceaous crops in June 2008 as a result of the establishment of tomato/potato psyllid (Bactericera cockerelli) in New Zealand. Tomato/potato psyllid is the vector for a new species of bacterial plant disease Candidatus spp. (Horticulture NZ 2008, Watson 2009).
The industry has been moving towards lower use of insecticides and use of insecticides that only target specific insect pests. Insecticides currently registered for use on tamarillos are listed in Table 10. However, existing spray programmes have not controlled tomato/potato psyllid infestations. Trials of possible alternative products have found Calypso® (thiacloprid), Chess® (pymetrozine), SuccessTM NaturalyteTM, Applaud® (buprofezin), Oberon®
(spiromesifen) and Coragen® (chlorantraniliprole) do not control tomato/potato psyllid at label rates. Contact insecticides such as Nuvos® (dichlorvos), Decis® Forte (deltamethrin) and Avid® (abamectin) have shown greater control (Watson 2009).
Dichlorvos (Nuvos®) is used by the tamarillo industry. Frequency of dichlorvos use by the tamarillo industry varies but common practice is twice a season. Nuvos® has a short pre- harvest interval of seven days for local and export fruit. The only other contact insecticide currently registered on tamarillo has a long pre-harvest interval of 60 days on export fruit, but seven days on fruit destined for the local market. With the recent establishment of
tomato/potato psyllid, dichlorvos usage will have increased during the 2009 season, as the dichlorvos products Nuvos® and DivapTM are the only contact insecticides available for export production (C Watson, pers. comm.).
In 2009, tomato/potato psyllid infestation caused up to 60% tree death, devastating some crops (C Watson, pers. comm.). This is an industry that currently needs all options available to it to be able to produce a commercial tamarillo crop. Dichlorvos is the only registered insecticide option currently found to be effective for tomato/potato psyllid control.
Table 10. Insecticides registered for use on tamarillo in New Zealand (Novachem 2009).
Chemical Group Active Ingredient
Registered Products1 Target Pest
Carbamate carbaryl Carbaryl 50F, Sevin®
Flo
Caterpillar, grass grub beetle, leafroller Organophosphate acephate Lancer® 750 DF,
Orthene® WSG
Aphids, caterpillars, grass grub beetle
Organophosphate diazinon DewTM 500, Diazinon 50W, Diazinon EC, Diazinon 800, Diazinon 800 EC, Diazonyl® 60EC, DigrubTM, Diazol®, Hortcare Diazinon 500EW
Aphids, caterpillars, whitefly, grass grub beetle
Organophosphate dichlorvos Nuvos®, DivapTM Aphids, caterpillars, whitefly. Some control of tomato/potato psyllid.
Short pre-harvest interval of 7 days for local and export.
Pyridine azomethine
pymetrozine Chess® WG Aphids, whitefly. Does not control tomato/potato psyllid
Synthetic pyrethroid deltamethrin Decis® Forte,
BallisticTM, Deltaphar®
25 EC
Whitefly, grass grub.
Some control of tomato/potato psyllid.
Short pre-harvest interval of 7 days for local but 60 days for export.
Synthetic pyrethroid taufluvalinate Mavrik® Aqua Flo Green peach aphid, whitefly
Thiadiazine buprofezin Applaud® 40 SC, Buprimax, MortarTM, Pilan® 25WP, OvationTM 50 WDG
Whitefly. Does not control tomato/potato psyllid
1Novachem 2009
Berryfruits
The New Zealand berryfruit industry comprises approximately 360 growers, accounting for a planted area of 2451ha. The domestic crop is valued at NZ$63 million and NZ$24 million in export value (Plant & Food Research 2008).
Dichlorvos was not used on blackcurrant, Boysenberry and blueberry export crops in 2009 with the exception of one export blueberry grower who applied dichlorvos for bronze beetle control. Bronze beetle is becoming more widely recognised as a pest problem on
blueberries. The beetles feed on the developing berries, reducing yields. As pest control programmes reduce the number of broad-spectrum products applied, beetles such as bronze beetle become more prevalent. Few products that have the necessary short pre- harvest interval to protect the developing fruit are effective against bronze beetle (G Langford, pers. comm.).
Strawberry growers and local market berry growers use dichlorvos mainly for carpophilus beetle (Carpophilus davidsoni Coleoptera:Nitiludae) control in the North Island (Skelton Ivory, Hastings, pers. comm.) and small amounts in the South Island for aphid and caterpillar control (M Ross, pers. comm.). Carpophilus beetle is currently found in the North Island and Nelson. Insect numbers are greater in hot dry seasons so the need for dichlorvos varies between seasons from none to approximately three applications. Like bronze beetle in blueberry, carpophilus beetle is increasing in significance as more persistent
organophosphates are removed from production programmes. A small trial in 2008 in Hawke’s Bay found mass trapping of carpophilus beetle in lure-and-kill traps was not effective enough to replace chemical control (P Lo, pers. comm.).
Growers are finding dichlorvos to be effective for carpophilus beetle control and it is likely to be an effective control option for bronze beetle control on blueberries. Its fumigant action gives good coverage and its short residual effect means it can be used close to harvest, while its broad-spectrum activity provides a useful option when growers are faced with unexpected and late season pest problems.
Ornamentals and Cut Flower Production
The domestic cut flower market is estimated to be worth NZ$60 million. The orchid cut flower export crop had a value of NZ$22.9 million in 2007. There are over 1200 flower growers, approximately 400 of which are full time producers (glasshouse and field production) (HortResearch 2007).
Dichlorvos has some use in ornamental and flower crops but is widely used in cymbidium orchids. It is used in cymbidium orchids because it is a useful insecticide for the control of scale insect in IPM programmes. While it is harmful to the adult and juvenile stages of the two-spotted mite predator, Phytoseiulus persimilis, Kopperts website (www.koppert.com) indicates that it is safe to the eggs of this predatory mite. Information from this website also indicates that the predatory mite can be reintroduced immediately after an application has been made. Increasing numbers of cymbidium orchid growers are using the predatory mite for two-spotted mite control, as they are unable to control this pest with the available miticides (P Workman, pers. comm.).
Mites are a key quarantine pest for export cut flowers. As dichlorvos has a short pre-harvest interval, wide pest control spectrum and fumigant activity, if mites or other insect pests are found in a crop, it can be treated then harvested the next day. The flowers can also be treated postharvest prior to sleeving (J Wilkinson, pers. comm.). The fumigant action is advantageous as it avoids blooms getting wet during treatment, which can cause disease.
There is also some interest in fumigation, with dichlorvos as an option to meet new lightbrown apple moth quarantine procedures for cut flowers and foliage to the USA (R Meinhardt, pers. comm.).
Glasshouse Vegetable Production
Dichlorvos is used fairly extensively in vegetable glasshouse production. It is widely used because it has a short pre-harvest interval and therefore applications of this product are not too disruptive to harvesting. Dichlorvos is also used widely because it can be applied effectively using foggers, as it has fumigant activity. This method of application is much quicker than applying a wet spray (P Workman, pers. comm.). Dichlorvos is frequently used as a clean-up treatment for glasshouse crop pests. It is also used strategically in
glasshouses to knock down pests, before re-introduction of bumble bees for pollination of tomato crops and predator mites for control of two-spotted mites (S McKenney, pers.
comm.). Dichlorvos is widely used in the glasshouse industry for controlling whitefly and aphids. The key reason for this is that there are no other products available with a fogging (fumigant) action (M Ross, pers. comm.).
There are no alternative insecticides with these properties of short pre-harvest interval, wide pest control spectrum and fumigant activity (P Workman, pers. comm.).
As a result of the establishment of tomato/potato psyllid in New Zealand, previously established integrated pest management (IPM) programmes in greenhouse tomato and capsicum crops have been severely disrupted, resulting in higher pesticide dependence.
Implications of this are reduced quality of pollination, reduced yield, lower fruit quality and a risk of pesticide resistance (Thompson 2009). Dichlorvos is listed as one of the insecticides that can be used for control of tomato/potato psyllid (Horticulture New Zealand 2008).
Mushrooms
There are 11 commercial mushroom growers in New Zealand, comprising a total production area of 42 hectares. The New Zealand mushroom crop volume is estimated at 8500 tonnes, valued at NZ$ 41.1 million in domestic sales and fresh exports of $NZ1.5 million (Plant &
Food Research 2008).
Few insecticides are used in mushroom production (Table 11). Where they are, preference is given to the insect growth regulator Dimilin® (diflubenzuron) for the control of sciarid flies (Lycoriella spp.). Mushroom growers do not currently use dichlorvos. However, the de- registration of dichlorvos would leave very few alternative insecticides available (M Speeden, pers. comm.).
Table 11. Insecticides registered for use on mushroom in New Zealand (Novachem 2009).
Chemical Group Active Ingredient Registered Products1
Target Pest
Biological control agent
Fungus gnat predator Hypoaspis (Gaeolealaps) aculeifer
EntomiteTM, Hypo- miteTM
Sciarid flies, thrips, some nematodes
Biological control agent
Steinernema feltiae Nemasys® Sciarid flies
Organophosphate dichlorvos Nuvos®, DivapTM Phorid & sciarid flies, mites, aphids, caterpillars, thrips, whitefly
Phenyl pryrazole fipronil Ascend® Sciarid, cecid &
phorid flies Substituted benzoyl
phenyl urea (insect growth regulator)
diflubenzuron Dimilin® 2L, Difuse®
25WP, PorinexTM SniperTM
Sciarid flies
1Novachem 2009
Field Vegetables
Growers do occasionally use dichlorvos in field vegetable production, in particular, for periods with particularly bad insect infestation problems. There are other insecticides from different chemical groups available for pest control, but dichlorvos is useful for a quick knockdown of high pest populations (C Cowell, S McKinney, pers. comm.).
Asparagus
There are 100 asparagus growers, with a planted area of 871 ha, producing 3136 tonnes with domestic sales valued at NZ$5.6 million, export sales at NZ$2.5 million and processed NZ$0.7 million (Plant & Food Research 2008).
Table 12. Insecticides registered for use on asparagus in New Zealand (Novachem 2009).
Chemical Group Active Ingredient Registered Products1
Target Pest
Synthetic pyrethroid esfenvalerate Sumi-alpha® Garden weevil Organophosphate dichlorvos Nuvos®, DivapTM Aphids, caterpillars,
mites, thrips
1Novachem 2009
Fumigation of fresh asparagus with dichlorvos incorporated with a gas propellant product (Insectigas®) is standard practice for export asparagus (Table 12). The treatment is to eliminate thrips in particular, which pose a quarantine pest risk to some export markets (especially Japan). The only alternative is methyl bromide, which has to be used at 23°C, shortening the shelf life of the asparagus. Dichlorvos has superior efficacy, proven cost
effectiveness, excellent penetration (semi-fumigant action) and rapid knockdown (D Brash, P Falloon, pers. comm.).
Japan is currently demanding a Dichlorvos Residue Approval Programme (DRAP) to provide assurance that dichlorvos has not been used on fresh produce exported to Japan (C Ward, pers. comm.). Research into a suitable long-term alternative for the postharvest treatment of asparagus for thrips control, such as hot water treatment, has so far been unsuccessful (D Brash, pers. comm.; Ward 2009).
Pasture and Cereals
There is little use of dichlorvos on cereal crops where synthetic pyrethroids are used to control aphids and caterpillar pests (N Pyke, pers. comm.). Insectigas® is registered for use in grain storage but it is unknown whether it is used for this purpose in New Zealand.
Dichlorvos is not used on ryegrass (N Pyke, pers. comm.). However, trichlorfon is
occasionally used for porina control in Southland pasture. Trichlorfon (sold as TrifonTM) is a broad-spectrum organophosphate that is registered for use on a range of field crops and pasture. Because of its low level of use, it is likely TrifonTM will be voluntarily withdrawn from market (W Palleson, pers. comm.).
Clover Seed and Vegetable Seed Production
Dichlorvos has been replaced with synthetic pyrethroids (e.g. Mavrik®) for control of clover case bearer, thrips and aphids. Synthetic pyrethroids are a cost-effective alternative, at approximately NZ$ 4-6 per hectare. While clover root weevil has been a recent problem in pasture, it is not seen as a major problem in seed production, since clover grown for seed production is only in the ground for two years, which does not give enough time for clover root weevil to establish (N Pyke, pers. comm.).
A small amount of dichlorvos may be occasionally used for vegetable seed production, but there are pollination issues (i.e. safety to bees) associated with its use. There are 2-3,000 ha of vegetable seed crops (N Pyke, pers. comm.), returning NZ$30 million in 2007 (HortResearch 2007).
Turf
In 2006, it was estimated there is a turf grass area of 58,139 ha managed for both sports and amenity uses (Haydu et al. 2008).
The main pests in turf management are porina, weevils, grass grub, black beetle, crickets and worms. Worm levels are higher in New Zealand than overseas because of our high organic matter. Typical water rates used on turf are 200-300 litres per ha applied with a boom sprayer. Rates can be as high as 600-800 litres per hectare where soil irrigation is needed to target a specific issue. The number of insecticide applications made per year depends on the field purpose and pest problem. There are 0-3 insecticide applications made per year on fairways, with up to 10 on a high quality green. On sports fields, insecticide use is much lower, estimated at once every three years for worms, and once every two years for porina, where porina is a problem (B Hannan, pers. comm.).
Dichlorvos is not currently used in turf management. Pest control options in turf management are diazinon, chlorpyrifos and synthetic pyrethroids, depending on the target pest.
Trichlorfon may be used to target specific problems such as porina moth (B Hannan, pers.
comm.).
Fruit fly Surveillance Programme
New Zealand has a unique position in that it is free from fruit flies (Diptera: Tephritidae). The severe economic impact of even a temporary establishment of fruit flies represents a major biosecurity threat to New Zealand’s horticulture industry, which was worth $2.9 billion in exports in 2008 (Plant & Food Research 2008; Suckling et al. 2008).
The absence of fruit fly species represents a very significant export market advantage allowing fresh export produce to be certified as free of infestation and exported to areas where fruit flies do not occur. It allows fruit fly-susceptible crops to be produced in New Zealand without a need for the management of this pest, which results in savings in terms of pest management inputs. The Ministry of Agriculture and Forestry Biosecurity New Zealand (MAFBNZ) operates a nationwide surveillance trapping programme at a cost of
approximately $1.2 million per annum (MAFBNZ 2009). This programme was initiated in the mid 1970s to provide trading partners with an auditable assurance that New Zealand
remains free of fruit flies, and is designed to detect incursive fruit fly populations quickly, so that they may be efficiently eradicated (Suckling et al. 2008; MAFBNZ 2009)
Central to the programme are about 7385 Lynfield traps deployed at 3518 sites at a range of locations based on incursion risk profile, with the largest number (about 67%) in Auckland and fewer than 18% of the traps in the South Island. The fruit fly traps are set up according to a MAF specification and only by contract operators, who have to undergo training and subsequent auditing of procedures. Any changes to operational procedures must be made with caution, to avoid losing sensitivity of the surveillance operation (MAF 2004; Suckling et al. 2008;MAFBNZ 2009).
The DDVP insecticide strips are used as a rapid knock down insecticide to male fruit flies attracted by lures (attractant) in fruit fly traps. A rapid knock down insecticide is needed to ensure trapped fruit flies that are attracted by the lure will remain in the insect trap for later collection and identification. Different lures are used in the insect trap depending on the type of fruit fly species. There are several thousand fruit fly species, but few are very
economically important. The lures used in the fruit fly traps in New Zealand are primarily targeting Queensland fruit fly (Ceratitis capitata (Weid)), Froggatt (Bactrocera tryoni), melon fly (B. cucurbitae (Coquillet)), Oriental fruit fly (B. dorsalis (Hendel)) and other male lure- responsive species (MAF 2004; Suckling et al. 2008).
Fruit fly traps are usually set up from late August in northern New Zealand, and later in the year further south as the temperatures increase. The traps remain in place until June of the following year. The traps are placed either 400 or 1200 metres apart (one to eight traps per km2), depending on the type of lure. The traps are placed in potential host plants, are not hung below foliage and no closer than 1.3 metres to the ground. If there is more than one trap on a property, then these are not placed in the same tree and must be at least three metres apart. Each trap is inspected two-weekly and the DDVP insecticide strip is replaced six-weekly. Replacement of the lure is six or 12-weekly depending on the type of lure (MAF 2004).
DDVP insecticide strips are used in fruit fly traps overseas. The recommended alternative depends on the trap type used but most commonly is a cotton wick soaked in dichlorvos, maldison (Malathion) or naled. Malathion and naled are organophosphates and are not available in New Zealand (IAEA 2003). There are currently no alternatives available to replace DDVP insecticide strips in the New Zealand fruit fly surveillance programme (V Thomson, pers. comm.).
Conclusions and Recommendations
Trichlorfon (sold as TrifonTM) is a broad-spectrum organophosphate that is registered for use on a range of field crops and pasture. Little TrifonTM is used in New Zealand, with only some minor use for the control of porina larvae in Southland pasture and possibly in turf
management. As a result of its low level of use, it is likely TrifonTM will be voluntarily withdrawn from market.
Dichlorvos is an inexpensive but effective broad-spectrum organophosphate insecticide registered for use on a wide range of horticultural crops in New Zealand. It also has public health uses for the indoor and outdoor control of pests such as flies, cockroaches, and ants, and food storage pests such as flour beetles and grain weevils. The main horticultural sectors currently using dichlorvos are cut flowers, particularly orchid production, glasshouse vegetables, field vegetables, persimmon, tamarillo, passionfruit, berryfruits, postharvest fumigation of asparagus and it is used in fruit fly surveillance traps. However, there is also occasional use on other crops such as vegetable seed production and ornamentals, and potential use in grain and food storage silos and warehouses.
Dichlorvos is sold for use in horticulture as two formulations, as an emulsifiable concentrate (sold as Nuvos® and DivapTM) and as an aerosol (sold as ArmourCrop DDVP and
Insectigas®). It is also available to MAF Biosecurity contained in vapour-releasing strips (DDVP Insecticide Strips), which are used in New Zealand’s fruit fly surveillance traps.
Dichlorvos has superior efficacy, proven cost effectiveness, excellent penetration (semi- fumigant action) and rapid knockdown. Its short residual effect means it can be used close to harvest, while its broad-spectrum activity provides a useful option when growers are faced with new pests or unexpected or late season pest build-ups. Its efficacy across a wide range of pests, short residual effect, unique fumigant activity and rapid knockdown make it ideal for pre-harvest and postharvest disinfestation to meet quarantine regulations, while these properties also provide a range of application options to fit with packing and handling
systems. The unique properties associated with dichlorvos mean that most of its uses are for specific purposes for which there are few if any alternatives.
Persimmon
Dichlorvos is used as a pre-harvest for the control of passenger pests such as oribatid mites.
Its short pre-harvest interval enables it to be used close to harvest as a clean-up spray. It is effective against a wide range of insects and its fumigant activity provides control into calyx cracks and under sepals that cannot be achieved through the use of other chemical formulations and spray techniques. With 90% of the persimmon crop exported, it is important that these passenger pests are controlled. Postharvest treatments have not proved to be economically viable options, do not fit with current fruit transport and handling systems and there are fruit damage risks. There are no current alternatives that have the unique mode of action provided by dichlorvos that are effective in controlling these pests.
Tamarillo
Dichlorvos (Nuvos®) is used by the tamarillo industry. Nuvos® has a short pre-harvest interval of seven days for local and export fruit. The only other contact insecticide currently registered on tamarillo has a long pre-harvest interval of 60 days on export fruit, but seven days on local fruit. In 2009, tomato/potato psyllid infestation caused up to 60% tree death devastating some crops. This is an industry that currently needs all options available to it to be able to produce a commercial tamarillo crop. Dichlorvos is the only registered insecticide option currently found to be effective for tomato/potato psyllid control.
Passionfruit
Until recently, the industry also used Malathion 50 EC, for which MRLs exist in the USA, but in June 2009 this product was voluntarily withdrawn from the New Zealand market by the distributor Nufarm Ltd. The main export market is USA. There is no MRL for diazinon or dichlorvos into this market; however, because of its short residual effect, dichlorvos is the only insecticide currently available for thrip control for passionfruit for the USA market.
Dichlorvos and diazinon are the only two insecticides specifically registered for use on passionfruit in New Zealand.
Berryfruits
Strawberry growers and local market berry growers are using dichlorvos mainly for
carpophilus beetle control in the North Island and small amounts are being used in the South Island for aphid and caterpillar control. Dichlorvos was not used in any blackcurrant or Boysenberry export crops in 2009 and only one export blueberry grower applied dichlorvos for bronze beetle control.
As pest control programmes reduce in broad-spectrum activity, beetles such as bronze beetle and carpophilus beetle become more prevalent. Berryfruit growers are finding dichlorvos to be an effective control where there are few alternatives. Its fumigant action gives good coverage and short residual effect means it can be used close to harvest, while its broad-spectrum activity provides a useful option when growers are faced with unexpected and late season pest problems.
Ornamentals and Cut Flower Production
Dichlorvos is less widely used in ornamental and flower crops than in glasshouse vegetable crops, with the exception of cymbidium orchids. It is used in cymbidium orchids because it is a useful insecticide for the control of scale insect in IPM programmes. Increasing numbers of cymbidium orchid growers are using the predatory mite for two-spotted mite control, as they are unable to control this pest with the available miticides.
Mites are a key quarantine pest for export cut flowers. As dichlorvos has a short pre-harvest interval, wide pest control spectrum and fumigant activity, this means that if mites or other insect pests are found in a crop, it can be treated then harvested or packed the next day.
The fumigant action is advantageous as it avoids blooms getting wet during treatment which can cause disease. There is also some interest in fumigation with dichlorvos, as an option to meet new lightbrown apple moth quarantine procedures for cut flowers and foliage to the USA.
Glasshouse Vegetable Production
Dichlorvos is used fairly extensively in glasshouse vegetable production. It is widely used because it has a short pre-harvest interval and therefore applications of this product are not too disruptive to harvesting and it can be applied effectively using foggers, as it has fumigant activity. Dichlorvos is frequently used as a clean-up treatment for glasshouse crop pests including whitefly and aphids. It is also used strategically in glasshouses to knock down pests, before re-introduction of bumble bees for pollination of tomato crops and predator mites for control of two-spotted mites. There are no alternative insecticides with these properties of short pre-harvest interval, wide pest control spectrum and fumigant activity.
As a result of the establishment of tomato/potato psyllid in New Zealand, previously established integrated pest management (IPM) programmes in greenhouse tomato and capsicum crops have been severely disrupted, resulting in higher pesticide dependence.
Dichlorvos is listed as one of the insecticides that can be used for control of tomato/potato psyllid.
Mushroom
Few insecticides are used in mushroom production. When they are, preference is given to the insect growth regulator Dimilin® (diflubenzuron) for the control of sciarid flies (Lycoriella spp). Mushroom growers do not currently use dichlorvos. However, the de-registration of dichlorovs would leave very few alternative insecticides available.
Field Vegetables
Growers do occasionally use dichlorvos in field vegetable production, in particular, for periods with particularly bad insect pest problems. There are other insecticides from different chemical groups available for pest control, but dichlorvos is useful for a quick knockdown of high pest populations.
Asparagus
Fumigation of fresh asparagus with dichlorvos incorporated with a gas propellant product (Insectigas®) is standard practice for export asparagus. The treatment is to eliminate thrips in particular, which pose a quarantine pest risk to some export markets (especially Japan).
Dichlorvos has superior efficacy, proven cost effectiveness, excellent penetration (semi- fumigant action) and rapid knockdown.
Japan is currently demanding a Dichlorvos Residue Approval Programme (DRAP) to provide assurance that dichlorvos has not been used on fresh produce exported to Japan. Research into a suitable long-term alternative for the postharvest treatment of asparagus for thrip control has so far been unsuccessful.
Pasture and Cereals
There is little use of dichlorvos on cereal crops: synthetic pyrethroids are typically used to control aphids and caterpillar pests. Insectigas® is registered for use in grain storage but it is unknown whether it is used for this purpose in New Zealand. Dichlorvos is not used on ryegrass. However, trichlorfon (sold as TrifonTM) is occasionally used for porina control in Southland pasture. Because of its low level of use, it is likely that TrifonTM will be voluntarily withdrawn from market.
Clover seed and Vegetable Seed Production
Dichlorvos has been replaced with synthetic pyrethroids (e.g. Mavrik®) for control of clover case bearer, thrips and aphids. A small amount may be occasionally used for vegetable seed production, but there are pollination issues (i.e. safety to bees) associated with its use.
Turf
Dichlorvos is not currently used in turf management. Trichlorfon may be used to target site specific problems such as porina moth.
Fruit fly Surveillance Programme
New Zealand has a unique position in that it is free from fruit flies (Diptera: Tephritidae). The severe economic impact of even a temporary establishment of fruit flies represents a major biosecurity threat to New Zealand’s horticulture industry. Central to the programme are about 7385 Lynfield traps deployed at 3518 sites at a range of locations based on incursion risk profile, with the largest number (about 67%) in Auckland and fewer than 18% of the traps in the South Island. DDVP insecticide strips are used in the traps as a rapid knock- down insecticide to fruit flies attracted by lures (attractant) in the fruit fly traps. A rapid knock-
