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Improved Fumigation for Export Wildfowers A report for the Rural Industries Research and Development Corporation by P. Williams May 2000 RIRDC Publication No 00/41 RIRDC Project No DAV-149A
Improved Fumigation for
Export Wildfowers
A report for the Rural Industries Research and Development Corporation by P. Williams
May 2000 RIRDC Publication No 00/41 RIRDC Project No DAV-149A
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© 2000 Rural Industries Research and Development Corporation. All rights reserved. ISBN 0 642 58074 X ISSN 1440-6845 Improved Fumigation for Export Wildflowers Publication No. 00/41 Project No. DAV-149A The views expressed and the conclusions reached in this publication are those of the author and not necessarily those of persons consulted. RIRDC shall not be responsible in any way whatsoever to any person who relies in whole or in part on the contents of this report. This publication is copyright. However, RIRDC encourages wide dissemination of its research, providing the Corporation is clearly acknowledged. For any other enquiries concerning reproduction, contact the Publications Manager on phone 02 6272 3186. Researcher Contact Details Dr Peter Williams Agriculture Victoria Institute for Horticultural Development Private Bag 15 South Eastern Mail Centre Victoria 3176 Phone: 03 9210 9222 Fax: 03 9800 3521 Email: [email protected]
RIRDC Contact Details Rural Industries Research and Development Corporation Level 1, AMA House 42 Macquarie Street BARTON ACT 2600 PO Box 4776 KINGSTON ACT 2604 Phone: 02 6272 4539 Fax: 02 6272 5877 Email: [email protected]. Website: http://www.rirdc.gov.au Published in May 2000 Printed on environmentally friendly paper by Canprint
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Foreword Exports of cut flowers from Australia were estimated to be worth $A30.1 million in 1995/96 with wildflowers comprising over 90% of the total. In 1998/99 the value of exports from Victoria was $A7.6 million a 25% increase from 1997/98. Insect infestations in the flowers and foliage have caused importing countries to fumigate and downgrade or reject consignments of flowers. The main fumigant used for quarantine treatments is methyl bromide, but it damages some flowers and it has been identified as an ozone depleting chemical. Many uses for methyl bromide are now being phased out in accordance with the Montreal Protocol, an international agreement to which Australia is a signatory. RIRDC supported a project (DAV-90A) to identify potential alternatives for fumigation of wildflowers. Phosphine was identified as the most promising of seven different fumigants tested. Data on use of ECO2FUME (previously named Phosfume), a cylinder gas formulation of phosphine, for fumigation of wildflowers was generated and passed to the manufacturer, BOC Gases, as the basis of an application for registration. This project has the aim of further improving fumigation techniques for disinfestation of wildflowers. Methods of reducing the exposure time required for fumigations have been investigated, particularly the impact of using additional carbon dioxide in fumigations. Further data has been generated extending the ranges of insects and wildflowers treated. This data, together with that obtained previously, has resulted in registration of ECO2FUME for postharvest disinfestation of cut flowers. This report, a new addition to RIRDC’s diverse range of over 450 research publications, forms part of our new wildflower and native plant R&D program, which aims to improve the profitability, productivity and sustainability of the Australian wildflower and native plant industry. Most of our publications are available for viewing, downloading or purchasing online through our website: • downloads at www.rirdc.gov.au/reports/Index.htm • purchases at www.rirdc.gov.au/pub/cat/contents.html Peter Core Managing Director Rural Industries Research and Development Corporation
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Acknowledgements This research was undertaken as an initiative of RIRDC which supplied core funding. Further financial support and contributions in kind were received from; Associated Flowers International, Ausflora Pacific Pty. Ltd., Austbloom Pty. Ltd., BOC Gases, Floratrade International and G.W. & L.R. Winfield. Thanks are also due to Ms. F. M. Horlock, Dr. J. D. Faragher and Mr. A. T. Slater for vase life assessments of flowers and to Mr. J. P. Lopresti for diagrams of the fumigation chamber.
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Contents
Foreword .................................................................................................................... iii
Acknowledgements.....................................................................................................iv
Executive Summary................................................................................................... vii
1. Introduction............................................................................................................. 1
2. Objectives............................................................................................................... 1
3. Methodology ........................................................................................................... 2 3.1 Target Species of Arthropods............................................................................ 2 3.2 Bioassays .......................................................................................................... 3 3.3 Analysis of Gas Concentrations ........................................................................ 3 3.4 Vase Life of Flowers Fumigated with Phosphine............................................... 3
3.4.1 Experiments with Bunches of Flowers and Foliage.................................... 3 3.4.2 Experiments with Waratahs ........................................................................ 4 3.4.3 Experiments with Thryptomene.................................................................. 4
3.5 Application of Phosphine................................................................................... 5 3.5.1 Fumigant Mixtures...................................................................................... 5 3.5.2 Operation of Fumigation Chamber............................................................. 6
4. Results.................................................................................................................... 8 4.1 Bioassays .......................................................................................................... 8 4.2 Vase Life Experiments ................................................................................... 16
4.2.1 Experiments with Bunches of Flowers and Foliage.................................. 16 4.2.2 Experiments with Leptospermum............................................................. 19 4.2.3 Experiments with Waratahs ..................................................................... 19 4.2.4 Experiments with Thryptomene................................................................ 20
5. Discussion ............................................................................................................ 22 5.1. Bioassays ...................................................................................................... 22 5.2. Vase Life Experiments .................................................................................. 22
6. Conclusions .......................................................................................................... 23
7. References ........................................................................................................... 24
8. Appendix............................................................................................................... 25
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List of Figures Fig. 1: Larvae of moth M1 on Thryptomene calycina....................................................... 2 Fig. 2 Diagram of 27 m3 commercial fumigation chamber used in disinfestation
experiments with details of gas circulation and heating system. .......................... 7
List of Tables Table 1 Effects of fumigations with Pestigas®, carbon dioxide and ECO2FUME on
Strepsicrates ejectana ......................................................................................... 8 Table 2 Effects of fumigations with Pestigas® and ECO2FUME on Strepsicrates
ejectana............................................................................................................... 8 Table 3 Effects of fumigations with Pestigas®, carbon dioxide and ECO2FUME on
Iridomyrmex purpureus, meat ant........................................................................ 9 Table 4 Effects of fumigations with Pestigas® and ECO2FUME on Iridomyrmex
purpureus, meat ant. ......................................................................................... 10 Table 5 Effects of fumigations with Pestigas®, carbon dioxide and ECO2FUME on
Myzus persicae, Green Peach Aphid................................................................. 10 Table 6 Effects of fumigations with Pestigas® and ECO2FUME on Myzus persicae,
Green Peach Aphid ........................................................................................... 11 Table 7 Effects of fumigations with Pestigas® carbon dioxide and ECO2FUME on
Forficula auricularia, European Earwig .............................................................. 11 Table 8 Effects of fumigations with Pestigas® and ECO2FUME on Forficula auricularia,
European Earwig ............................................................................................... 12 Table 9 Effects of fumigations with Pestigas®, carbon dioxide and ECO2FUME on
Liposcelis sp., Psocidae .................................................................................... 12 Table 10 Effects of fumigations with Pestigas® and ECO2FUME on Liposcelis sp., ........ 13 Table 11 Effects of fumigations with Pestigas® and ECO2FUME on Macrosiphon rosae,
Rose aphid ........................................................................................................ 13 Table 12 Effects of fumigations with Pestigas® and ECO2FUME on Orosius argentatus
Common brown leafhopper ............................................................................... 14 Table 13 Effects of fumigations with Pestigas® and ECO2FUME on Psyllid .................... 14 Table 14 Effects of fumigations with Pestigas® and ECO2FUME on Rutherglen Bug...... 14 Table 15 Effects of fumigations with Pestigas and ECO2FUME on White mealybug..... 15 Table 16 Effects of fumigations with Pestigas® and ECO2FUME on moth larvae (M1) ... 15 Table 17 Effects of Fumigation on Cut Flowers and Foliage Treated with Pestigas and
ECO2FUME for 15 - 16 Hours.......................................................................... 17 Table 18 Effects of Fumigation on Cut Flowers Treated with Pestigas and ECO2FUME
for 15 Hours....................................................................................................... 18 Table 19 Effects of Fumigation on Leptospermum cultivars Treated with Pestigas and
ECO2FUME for 15 Hours. ................................................................................ 19 Table 20 Effects of Fumigation on Waratahs cv. Gembrook Treated with Pestigas,
carbon dioxide and ECO2FUME for 13 Hours. ................................................. 20 Table 21 Effects of Fumigation on Thryptomene Treated with Pestigas and ECO2FUME
for 15 Hours....................................................................................................... 20 Table 22 Effects of Fumigation on Thryptomene Treated with Pestigas and ECO2FUME
for 15 Hours....................................................................................................... 21 Table 23 Effects of Fumigation on Thryptomene Treated with Pestigas and ECO2FUME
for 15 Hours....................................................................................................... 21
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Executive Summary
Background Exports of cut flowers and foliage from Australia are expanding. In 1998/99 the value of exports from Victoria was $A7.6 million a 25% increase from 1997/98. Wildflowers comprised most of this increase. Detection of live insects in consignments of flowers has resulted in importing countries fumigating and downgrading or rejecting consignments. Methyl bromide is generally used for such treatments, but it can damage some flowers and it has been identified as a major ozone depleting chemical. Its use is now being restricted by international agreement. A project supported by RIRDC identified phosphine as a potential alternative and developed a fumigation schedule for treatment of wildflowers with Phosfume (renamed ECO2FUME), a cylinder gas formulation of phosphine. This project aims to further improve the fumigation schedule, extend the range of insects and wildflowers tested, and assist the manufacturer, BOC Gases, in registering the product for fumigation of cut flowers.
Research Experiments were conducted in a 27 m3 modified shipping container set up to allow introduction of the aerosol Pestigas® (0.4% pyrethrum and 2% piperonyl butoxide with carbon dioxide as a carrier gas), Phosfume (2% phosphine with carbon dioxide as a carrier gas) and carbon dioxide. Fumigation schedules tested involved combinations of Pestigas® and Phosfume with exposure times of 13 and 15 hours and combinations of Pestigas®, carbon dioxide and Phosfume with exposure times of 8 and 13hours. A wide range of cut flowers could be fumigated with any of the fumigation schedules tested without their marketability being impaired. Vase life experiments extended the range of flowers and foliage shown to be suitable for phosphine fumigation with most tests involving combinations of Pestigas® and Phosfume with an exposure time of 15 hours. Some insects survived treatment with Pestigas® and Phosfume for 13 hours but most were killed in 15 hour exposures. The application for registration, supported by data from both this and the previous project, was made on the basis of applying Phosfume alone or in combination with Pestigas® for 15 hours at a minimum temperature of 15oC. A change of name from Phosfume to ECO2FUME was requested. In experiments where additional carbon dioxide was applied with Pestigas® and Phosfume, the 8 hour exposure failed to kill all target insects. However, the 13 hour treatment proved effective and could provide a basis for reducing the recommended fumigation time. The addition of carbon dioxide appeared to be important as 13 hour fumigations without it were not as effective.
Outcomes The phosphine formulation ECO2FUME (formerly Phosfume) is now registered for fumigation of cut flowers. Registration became effective in March 1999. ECO2FUME can be applied alone to give a phosphine concentration of 700ppm (approximately 1gm-3) or in combination with Pestigas® in which case the phosphine concentration can be reduced. The exposure period is 15 hours at a minimum temperature of 15oC. This project has contributed to the registration of an exposure period of 15 rather than 16 hours. It has also demonstrated the potential for a further reduction to 13 hours if additional carbon dioxide is applied. The range of insects controlled by the fumigation and the range of flowers shown to be suitable for fumigation have been extended.
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Ausflora Pacific Pty. Ltd., Gembrook, Victoria regularly use the fumigation technique for treatment of export consignments of cut flowers.
Implications Fumigation of cut flowers with ECO2FUME provides a useful alternative to methyl bromide for control of a range of insect pests. ECO2FUME has handling advantages compared with solid phosphine generating formulations, which take time to generate a required phosphine concentration and leave unexpended residues, which must be disposed of after fumigation. These advantages make ECO2FUME not only suitable for treatment of flowers but give it the potential for use on other horticultural produce.
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1. Introduction Exports of Australian cut flowers and foliage were estimated to be worth $A23.1 million in 1992/93 and $A30.1 million in 1995/96 (Robins 1997). The market has the potential to expand. In 1998/99 the value of exports from Victoria was $A7.6 million a 25% increase from 1997/98. Most of the increase came from Australian wildflowers. In Australia methyl bromide is used by some exporters, particularly if insecticide dipping or treatment with pyrethrum and dichlorvos based aerosols has failed to control postharvest pest infestations. However, methyl bromide has been identified as a major ozone depleting chemical and its use is being limited in accordance with the Montreal Protocol. Consequently RIRDC supported a project to develop alternative fumigation techniques for treatment of wildflowers (Williams et al. 1998). The project identified phosphine as the most promising of seven fumigants that were assessed. Fumigation schedules using the cylinder gas formulation Phosfume (now renamed ECO2FUME) with exposure periods of 15 - 16 hours were developed for commercial use. The manufacturer, BOC Gases, was provided with data to form the basis of a submission to the National Registration Authority to extend registration to include fumigation of cut flowers. This new project aims to improve the phosphine fumigation technique already developed, extend the range of insects and wildflowers tested and investigate ways of reducing the exposure time required. Data gained through this project has assisted BOC Gases application for extension of registration of Phosfume and a change of name to ECO2FUME, which became effective in March 1999.
2. Objectives 1. To modify a new fumigation technique using phosphine to reduce treatment time to less than 16
hours. 2. To ensure experimental treatments (eg. phosphine and CO2) provide effective control of insect
pests without damage to flowers while enabling more rapid delivery of flowers from exporters to importers.
3. To extend testing from the key pests already assessed to other insects known to be associated
with cut flowers, this will increase confidence in the technique.
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3. Methodology
3.1 Target Species of Arthropods Larvae of the leaf rolling moth leaf rolling Tortricid moth, Strepsicrates ejectana (Walker) have caused rejections of consignments of Thryptomene and have proved difficult to control using insecticide dips. These larvae were exposed in most of the experimental fumigations to provide a means of comparing effectiveness. The aphid Myzus persicae (Sulzer) was used in a similar manner. The range of insects exposed was extended beyond that reported previously (Muhunthan et al. 1997, Weller et al. 1996, Williams 1996, Williams 1997, Williams and Muhunthan 1998) to include additional aphid species, thrips, moth larvae, psocids, mealy bugs, and bugs occurring on wildflowers. The European earwig Forficula auricularia L. which is often found inside Protea flowers and has caused rejections of consignments of flowers overseas was also included. Many of the earwigs fumigated in this study were collected by tapping Protea flowers over a white tray. In August 1999 bunches of Thryptomene were collected from the Austbloom plantation at Laharum for a fumigation and vase life experiment. At this time numerous moth larvae of a species previously not encountered were found amongst the Thryptomene flowers. These larvae (designated M1) were well camouflaged, their colouring resembling that of the flowers (Fig.1) and they could easily be included in consignments of flowers. Larvae were collected so that some could be fumigated with bunches of Thryptomene and others could be kept to be reared to the adult stage. Half of the larvae collected were placed on Thryptomene stems in open topped jars and exposed to 15 hour fumigations along with bunches of Thryptomene for vase life experiments. The rest were kept as unfumigated controls and then retained for breeding.
Fig. 1: Larvae of moth M1 on Thryptomene calycina
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3.2 Bioassays The insects exposed in the fumigations were housed in various containers so that they were available for assessment after completion of treatment. Glass jars (750ml) were used for some insects. A coating of Fluon (polytetrafluroethylene) was applied to the inside rim at the top of each jar to prevent insects from escaping. The jars were fitted with perforated screw-on lids when used to transport insects, and the lids were removed prior to fumigation. Plastic jars (2L) with terylene voile tops were also used and the tops were removed prior to fumigation. When insects were presented on potted plants they were housed in either (i) a cage with a solid plastic base, plastic frame with terylene voile sides 240 x 240 x 480mm and clip-on lid with a terylene voile centre, or (ii) a cage with a solid metal base, metal frame with terylene voile sides 480 x 480 x 630mm and perspex top. The latter cage had one of the terylene voile sides extended as a sleeve which allowed access to the inside of the cage. Ants, psocids and earwigs were fumigated in the 750ml jars which contained plant material for food and refuges and a pad soaked in sugar solution for the ants. Thryptomene cuttings containing mealy bugs, moth larvae and larval shelters of S. ejectana were generally fumigated in the 2L jars. Potted plants such as mallows, celery beans and Thryptomene infested with aphids, bugs and thrips were fumigated in one of the cages. Bioassay assessments were generally made at 4 - 6 hours and again at 22 - 24 hours after completion of a fumigation. On some occasions assessments were made after 48 hours or longer. Unfumigated control arthropods were kept in controlled temperature rooms at 20oC-22oC and 60%-65% RH. Bioassay assessments were generally made at 4 - 6 hours and again at 22 - 24 hours after completion of a fumigation. On some occasions assessments were made after 48 hours or longer. Unfumigated control arthropods were kept in controlled temperature rooms at 20oC-22oC and 60%-65% RH.
3.3 Analysis of Gas Concentrations Phosphine concentrations were measured using gas detector tubes (Dräger), a Photovac portable GC and a Canary phosphine detector. Carbon dioxide concentrations were measured using a Gow-Mac Gas Analyser. Details for obtaining this analytical equipment and other materials used in the fumigations are given in the Appendix.
3.4 Vase Life of Flowers Fumigated with Phosphine 3.4.1 Experiments with Bunches of Flowers and Foliage The range of flowers and foliage fumigated with ECO2FUME was extended beyond that previously reported (Williams et al. 1998) and observations were made on the vase life of these flowers compared with similar unfumigated control flowers. Only a limited numbers of bunches and stems of some of the flowers were available for testing. Bunches of flowers were fumigated while standing in buckets of water. Some bunches of Boronia were treated with silver thiosulphate (STS), to increase vase life by protecting stems from ethylene (Williamson 1999), before being fumigated. Most flower stems to be fumigated were placed in water shortly after being cut and were kept in water throughout the fumigation. Exceptions were bunches of flowers air lifted from Western Australia with their stems in damp potting mix and some bunches of Thryptomene that were
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fumigated flat with water sprayed foliage. It was important to keep the flowers well hydrated during fumigation otherwise they tended to dry out and deteriorate. This deterioration may have been caused by the temperature, respiration and transpiration rates during fumigation, the fumigant itself or a combination of these factors. Some flowers were selected for use in fumigation tests following requests by extension staff and exporters in Western Australia and Victoria. These flowers were ones recently being included in export consignments or considered “best bets” for future export programs, namely species and cultivars of Acacia, Actinotus, Banksia, Boronia, Conospermum, Eriostemon, Geleznowia, Hypocalmna, Isopogon, Leucadendron and Protea. Promising cultivars of Leptospermum being developed at the Institute for Horticultural Development, Knoxfield (IHD) and by growers in Victoria were also included in the tests. In the Leptospermum fumigations 0.03gm-3 of pyrethrum (applied as Pestigas®) followed 10 minutes later with 0.42 - 0.49gm-3 of phosphine (applied as ECO2FUME). Phosphine concentrations at the end of the 15 hour fumigations were 0.31 -0.35gm-3, details of the fumigation technique are given in the section on application of phosphine, page 6. After fumigation at Gembrook, bunches of flowers were transported to IHD, Knoxfield (travel time about 45 minutes, temperature about 20oC) where they were placed in a "flower room" with 12 hours light (10 µEm-2s) and 12 hours dark held at 20oC ± 1oC and 60 - 70% RH for vase life observations. Most vase life experiments assessed the condition of bunches of flowers with their stems in jars of water for 7 days after completion of a fumigation. Later experiments separated the bunches into individual stems, each with their own water container, and continuing assessment of each stem until the end of vase life. Assessments were carried out by flower research workers other than the author. 3.4.2 Experiments with Waratahs
Waratahs, Telopea speciosissima cv. Gembrook, were fumigated with Pestigas®, ECO2FUME and carbon dioxide to see if there was an advantage or disadvantage in the presence of additional carbon dioxide. Waratahs are known to produce ethylene, which accelerates senescence and it is possible that the carbon dioxide would suppress ethylene production. Six stems of waratah, cv. Gembrook were fumigated for 13 hours with 0.02gm-3 of pyrethrum, an initial concentration of 1.36gm-3 of phosphine and a final concentration of 0.96gm-3. Carbon dioxide was added following the application of pyrethrum (from Pestigas) and the concentration of carbon dioxide achieved was measured as 9.65% after addition of ECO2FUME (phosphine and carbon dioxide). Two stems were held as unfumigated controls. On completing the fumigation, stems were placed in individual water containers in the "flower room" for vase life observations. 3.4.3 Experiments with Thryptomene Some plants such as Thryptomene can close their stomata to retain water within their leaves. Spraying the foliage of such flowers with water after cutting enables the stomata to close in a humid atmosphere and assists in retaining water within the leaves. Further spraying with water can help limit loss of water by transpiration and help extend vase life. An exporter suggested that it could be useful to be able to load trolleys with bunches of such flowers, without placing the stems in water, spray the foliage with water and fumigate them overnight. Three trials were conducted in which bunches of Thryptomene calycina were treated in this manner. In the first trial 10 bunches of Thryptomene were cut at Laharum in the early morning. They were sprayed with water and transported in buckets of water to Gembrook for fumigation later the same day. Eight of the bunches were sprayed with water, placed on a trolley and fumigated overnight with 0.02gm-3 of pyrethrum (applied as Pestigas) followed 10 minutes later with 1.11gm-3 of phosphine (applied as ECO2FUME). Overnight temperatures were mild, about 18oC, so there was little call for heating (thermostat setting 20oC) and associated fan operation (which tends to increase gas
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leakage). The phosphine concentration at the end of the 15 hour fumigation was still 1.11gm-3 (presumably because of the favourable conditions). The temperature of the bunches during fumigation was about 19oC (based on data from 2 temperature data loggers). The recommended dosage for phosphine is 1gm-3, (50gm-3 of ECO2FUME) so the flowers were exposed to a severe fumigation test. The remaining 2 bunches (controls) were held in buckets of water overnight in the flower shed at Gembrook, where the temperature of 15oC to 17oC was lower than in the fumigation chamber. After completion of fumigation all the bunches were taken to the flower room for vase life assessment. Exporters can hold flowers, such as Thryptomene, in a cool room for a few days before they are included in a consignment to be sent to market. The second trial was conducted to simulate these circumstances. Ten bunches were collected and transported to Gembrook for fumigation as in the first trial. On this occasion the 8 fumigated bunches were treated with 0.01gm-3 of pyrethrum (applied as Pestigas) followed 10 minutes later with 1.11gm-3 of phosphine (applied as ECO2FUME). The phosphine concentration at the end of the 15 hour fumigation was 0.49gm-3 (overnight temperatures were lower than for the first trial). The temperature of the bunches during fumigation was about 19.5oC and the control bunches were held at about 20oC during the fumigation. After fumigation all the bunches were placed in a cool room, at 3.5oC – 4oC at the fumigation site, for 4 days before vase life assessments commenced. In a third trial, 6 bunches were collected and transported to Gembrook for fumigation as in the previous trials. In this trial, 1 bunch was an unfumigated control, 1 bunch was fumigated standing in a bucket of water and the remaining 4 bunches were sprayed with water and fumigated flat. On this occasion 0.02gm-3 of pyrethrum (applied as Pestigas) was used followed 10 minutes later by 1.04gm-3 of phosphine (applied as ECO2FUME). The phosphine concentration at the end of the 15 hour fumigation was 0.56gm-3. The temperature of the bunches during fumigation was about 20oC and control bunches were held at the same temperature. After fumigation the bunches were taken to the flower room and the stems were separated and placed in individual water containers for vase life assessment.
3.5 Application of Phosphine
3.5.1 Fumigant Mixtures
The phosphine formulation used was the cylinder gas formulation ECO2FUME (2% phosphine with carbon dioxide as a carrier gas). The fumigation chamber used was a 27 m3 modified shipping container set up for commercial use. In addition to being fitted for application of ECO2FUME, the chamber was fitted for application of the aerosols Pestigas® (0.4% pyrethrum and 2% piperonyl butoxide with carbon dioxide as a carrier gas) and Insectigas® (5% dichlorvos with carbon dioxide as a carrier gas) (Figure 2). Gas fittings for cylinders of Insectigas® and ECO2FUME are identical so the cylinders can be interchanged if necessary. In most fumigations carried out, 120 - 200 g of the aerosol Pestigas® (introduction time 5 - 10 seconds) was applied to agitate insects followed 10 minutes later by 1 - 2 kg of ECO2FUME (introduction time several minutes, varied with quantity remaining in cylinder) as the main killing agent. Pestigas® applications of 120 - 200 g were calculated to give pyrethrum concentrations of 0.02 - 0.03gm-3 in the fumigation chamber. Measurement of phosphine concentrations showed that applications of 1 - 2 kg of ECO2FUME generally resulted in initial concentrations of 0.49 - 1.0gm-3 of phosphine in the fumigation chamber. The exposure period was calculated from the time of completion of gas introduction. For most fumigations it was 15 hours, which is the time recommended for treatment of cut flowers on the new ECO2FUME label.
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Some fumigations were carried out using exposure times of 8 and 13 hours to see if it was feasible to reduce the fumigation time in some circumstances. In some of these fumigations, additional carbon dioxide was introduced from a cylinder into the chamber 10 minutes after application of Pestigas®. ECO2FUME was introduced following the addition of the carbon dioxide. Carbon dioxide is known to have some "synergistic" effects when used in conjunction with other fumigants. It can induce insects to open their spiracles and this may assist entry of fumigant gases. 3.5.2 Operation of Fumigation Chamber A temperature of 15oC or above is recommended for phosphine fumigations (Winks et al. 1980). Metal gas ducting attached to the fumigation chamber incorporated an industrial custom built heater rated at 3kW to obtain rapid and reliable heating to keep temperatures above 15oC during fumigations. The elements of the heater were sheathed in stainless steel, to protect against the corrosive action of phosphine on copper (Bond 1984). The impeller of a fan was also incorporated within the ducting. A shaft linked the impeller with a fan motor mounted outside the ducting. The fan recirculated gases during fumigation, distributing gases warmed by the heater throughout the fumigation chamber. Operation of the heater was controlled by a thermostat (range 0oC to 40oC), the sensor of which was placed in the centre of the inlet to the circular return gas port (Fig. 2). This enabled reliable measurement of the average temperature of gas that returned from the chamber, and thence that flowed through the electrical heater (Muhunthan et al., 1997). Operation of the fumigation chamber was checked during commercial fumigations of cut flowers before the experiments reported here commenced. It was found that, after achieving an initial phosphine concentration of about 0.49gm-3, the concentration declined to about 0.13gm-3 after a 15 - 16 hour fumigation. Some leaks were detected using the Canary phosphine detector and these were sealed with silicone rubber, with the exception of a leak around the fan shaft where it entered the gas ducting system used in recirculating, and heating gas during fumigation and in ventilating gas on completion of fumigation. During recirculation the shut-off valve in the purge duct was closed and the valve in the duct returning gas to the chamber was open, valve settings were reversed during ventilation (Fig. 2). When the doors were opened just enough to break the seals, the fan was efficient in ventilating the chamber, which was cleared of phosphine within about 15 minutes. However, it was noted that gas was being forced through leakage points by the pressure within the chamber generated by the fan when it was used for recirculating gases during fumigation. Leakage of phosphine was reduced by using the fan to recirculate gases at the start of a fumigation and then connecting it to a switch which only allowed power to operate the fan when the heater was switched on by its thermostat. In order to achieve greater efficiency of operation it was considered that a variable speed fan should be fitted and that a teflon seal should be installed around the fan shaft to reduce leakage. The lowest speed of the fan would be sufficient to mix gases within the chamber during fumigation and the highest speed would be used during ventilation. The fixed speed fan was replaced with a variable speed fan and a teflon seal was installed around the fan shaft. Then, phosphine leakage and pressure tests were conducted. No phosphine was detected around the teflon seal when the fan was operated. An inclined manometer was connected to the gas line used to monitor phosphine concentrations within the chamber. The manometer was used to measure the pressure generated within the chamber by the fan when operated at high and low speed. When set on maximum speed the fan generated a pressure of 57.29Pa, which was the same as that generated by the original fixed speed fan. When set on minimum speed the new fan generated a pressure of 14.95Pa. Thus the pressure generated within the chamber during fumigation was reduced by over 3.5 times. After these modifications it was found that in a typical 15 hour commercial fumigation the phosphine concentration decreased from 0.49gm-3 to 0.42gm-3.
Heated gas
Fumigant
Rear wall of chamber
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Fig. 2 Diagram of 27 m3 commercial fumigation chamber used in disinfestation experiments with details of gas circulation and heating system.
Fan inlet duct
Shut-off valve
Purge outlet
Shut-off
Fan outlet
Impeller
Fan motor
Fan controller
Fan Heater
Return gas
Thermostat
Fumigant
Heated gas
Rear wall of
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4. Results
4.1 Bioassays Two insect species, S. ejectana and Iridomyrmex purpureus (F. Smith) were exposed in an 8 hour fumigation with Pestigas®, carbon dioxide and ECO2FUME®. This treatment failed to kill all the S. ejectana larvae and pupae exposed (Table 1) and the severely affected larvae took up to 7 days to die. Most I. purpureus appeared dead immediately after fumigation, but recovered within 24 hours (Table 3). Thus the treatment was ineffective against this ant. Increasing the exposure time for Pestigas®, carbon dioxide and ECO2FUME® fumigations to 13 hours improved effectiveness against insect pests. Larvae and pupae (few of which were available) of S. ejectana were killed within 24 hours of completion of fumigation (Table 1). A similar result was achieved with larvae and adults of M. persicae (Table 5). Adults of I. purpureus, and larvae and adults of F. auricularia and Liposcelis sp were dead when assessed within 6 hours after treatment (Tables 3, 7 and 9). In fumigations with Pestigas® and ECO2FUME® without additional carbon dioxide 13 hours exposure proved insufficient to kill all larvae and pupae of S. ejectana and M. persicae that were treated (Tables 2 and 11). Fifteen hours treatments with Pestigas® and ECO2FUME® were found to be effective in killing a range of insects: - S. ejectana (Table 2), I. purpureus (Table 4),M. persicae (Table 6), F. auricularia (Table 8), psocids (Table 10), Macrosiphon rosae (L) (Table 11), Orosius argentatus (Evans), (Table 12), psyllids (Table 13), Nysius vinitor Bergroth (Table 14), white mealybugs (Table 15) and moth larvae M1 (Table 16). When the fumigation chamber was emptied dead insects, notably earwigs, were often found on the flower trolleys and on the floor. This indicated that the treatment had agitated the insects causing them to leave the flowers before dying. Table 1 Effects of fumigations with Pestigas®, carbon dioxide and ECO2FUME on Strepsicrates ejectana Exposure
time (h)
Temp. oC
Pyrethrum (g)
Carbon Dioxide (%)
Phosphine (gm-3)
Larvae Pupae
Initial Final Live S.Aff Dead Live S.Aff Dead
8 19.2 0.02 7.5 0.53 0.43 5 30 9 1 1 2 0 20.0 0 0 0 0 44 0 0 4 0 0 13 20.5 0.03 7.7 1.0 0.9 0 0 9 0 19.8 0 0 0 0 9 0 0 13 22.0 0.03 9.0 1.1 1.0 0 1* 10 0 0 3 0 20.2 0 0 0 0 11 0 0 3 0 0 13 19.6 0.02 9.7 1.36 0.96 0 5* 17 0 20.2 0 0 0 0 19 0 0 S.Aff = severely affected *dead within 24 hours. Table 2 Effects of fumigations with Pestigas® and ECO2FUME on Strepsicrates ejectana
9
Exposure
time (h)
Temp. oC
Pyrethrum (g)
Phosphine (gm-3)
Larvae Pupae
Initial Final Live S.Aff Dead Live S.Aff Dead
13 18.5 0.04 1.0 0.78 1 2 3 2 1 3 0 20.0 0 0 0 6 0 0 6 0 0 13 16.0 0.04 0.46 0.39 0 0 4 3 2 7 0 20.0 0 0 0 4 0 0 12 0 0 15 17.5 0.03 1.42 1.39 0 1* 8 0 0 1 0 20.0 0 8 0 0 1 0 0 15 18.2 0.02 0.64 0.45 0 1** 15 0 20.3 0 0 0 16 0 0 15 20.0 0.02 1.0 0.56 0 1* 7 0 20.0 0 0 0 9 0 0 15 17.7 0.03 0.63 0.53 0 0 20 0 20.1 0 0 0 20 0 0 S.Aff = severely affected *dead within 24 hours. **dead within 48 hours. Table 3 Effects of fumigations with Pestigas®, carbon dioxide and ECO2FUME on Iridomyrmex purpureus, meat ant.
Exposure time (h)
Temperature oC
Pyrethrum (g)
Carbon Dioxide
(%)
Phosphine (gm-3)
Adult Workers
Initial Final Live S.Aff Dead 8 19.2 0.02 7.5 0.53 0.43 125 0 10 0 20.0 0 0 0 0 133 0 2 13 20.5 0.03 7.7 1.0 0.9 0 0 12 0 19.8 0 0 0 0 12 0 0 13 19.5 0.03 9.5 1.4 1.3 0 0 107 0 20.2 0 0 0 0 106 0 1 13 22.0 0.03 9.0 1.1 1.0 0 0 115 0 20.2 0 0 0 0 113 0 2 13 17.8 0.03 4.4 1.0 0.9 0 0 83 0 20.0 0 0 0 0 83 0 0
S.Aff = severely affected
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Table 4 Effects of fumigations with Pestigas® and ECO2FUME on Iridomyrmex purpureus, meat ant.
Exposure time (h)
Temperature oC
Pyrethrum (g)
Phosphine (gm-3)
Adult Workers
Initial Final Live S.Aff Dead 15 17.8 0.03 1.00 0.91 0 0 83 0 20.1 0 0 0 83 0 0 15 18.8 0.03 1.11 0.72 0 26** 24 0 20.1 0 0 0 50 0 0 15 19.8 0.02 0.58 0.57 0 4* 24 0 20.1 0 0 0 28 0 0
S.Aff = severely affected *dead within 24 hours. **dead within 48 hours Table 5 Effects of fumigations with Pestigas®, carbon dioxide and ECO2FUME on Myzus persicae, Green Peach Aphid Exposure time (h)
Temperature oC
Pyrethrum (g)
Carbon Dioxide
(%)
Phosphine (gm-3)
Larvae & Adults Adults
Initial Final Live S.Aff Dead Live S.Aff Dead
13 22.0 0.03 9.0 1.1 1.0 0 1* 38 0 20.2 0 0 0 0 40 0 0 Larvae Live S.A
ff Dead
13 19.6 0.02 9.7 1.36 0.96
0 0 42 0 0 28
0 20.2 0 0 0 0 42 0 0 28 0 0 S.Aff = severely affected *dead within 24 hours.
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Table 6 Effects of fumigations with Pestigas® and ECO2FUME on Myzus persicae, Green Peach Aphid Exposure
time (h)
Temperature oC
Pyrethrum (g)
Phosphine (gm-3)
Larvae & Adults Adults
Initial Final Live S.Aff Dead Live S.Aff Dead 13 18.5 0.04 1.0 0.78 2 13 255 0 20.0 0 0 0 13 16.0 0.04 0.46 0.39 2 1 451 0 20.0 0 0 0 0 0 Larvae Live S.Af
f Dead
15 18.8 0.03 1.11 0.72 0 0 193 0 0 20 0 20.1 0 0 0 193 0 0 22 0 0 15 18.5 0.02 0.49 0.35 0 0 75 0 0 50 0 20.0 0 0 0 75 0 0 50 0 0 15 17.7 0.03 0.63 0.53 0 0 24 0 0 14 0 20.1 0 0 0 24 0 0 14 0 0 S.Aff = severely affected Table 7 Effects of fumigations with Pestigas® carbon dioxide and ECO2FUME on Forficula auricularia, European Earwig
Exposure time (h)
Temperature
oC
Pyrethrum (g)
Carbon Dioxide (%)
Phosphine (gm-3)
Larvae Adults
Initial Final Live S.Aff Dead Live S.Aff Dead
13 20.5 0.03 7.7 1.0 0.9 0 0 12 0 0 18 0 19.8 0 0 0 0 11 0 1 18 0 0 13 19.5 0.03 9.5 1.4 1.3 0 0 20 0 0 25 0 20.2 0 0 0 0 20 0 0 24 0 1 13 22.0 0.03 9.0 1.1 1.0 0 0 16 0 0 25 0 20.2 0 0 0 0 16 0 0 24 0 1 S.Aff = severely affected
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Table 8 Effects of fumigations with Pestigas® and ECO2FUME on Forficula auricularia, European Earwig Exposure
time (h)
Temperature oC
Pyrethrum (g)
Phosphine (gm-3)
Larvae Adults
Initial Final Live S.Aff Dead Live S.Aff Dead 4.5 19.0 0.02 0.3 0.3 0 0 8 0 22.0 0 0 0 8 0 0 6 18.0 0.02 0.9 0.9 0 0 12 0 22.0 0 0 0 12 0 0 15 22.2 0.04 0.9 0.8 0 0 7 0 0 20 0 22.3 0 0 0 7 0 0 20 0 0 15 17.5 0.03 1.42 1.39 0 0 19 0 0 26 0 20.0 0 0 19 0 0 26 0 0 15 21.1 0.02 0.56 0.42 0 0 20 0 0 100 0 20.5 0 0 0 20 0 0 100 0 0 15.3 20.3 0.04 0.49 0.42 0 0 18 0 0 24 0 20.1 0 0 0 18 0 0 24 0 0 15 19.5 0.02 1.11 1.05 0 0 15 0 0 21 0 20.0 0 0 0 15 0 0 21 0 0 15 18.2 0.03 0.49 0.31 0 0 15 0 0 32 0 20.0 0 0 0 15 0 0 32 0 0 S.Aff = severely affected Table 9 Effects of fumigations with Pestigas®, carbon dioxide and ECO2FUME on Liposcelis sp., Psocidae
Exposure time (h)
Temperature (oC)
Pyrethrum (g)
Carbon Dioxide
(%)
Phosphine (gm-3)
Liposcelis
Initial Final Live S.Aff Dead 13 20.5 0.03 7.7 1.0 0.9 0 0 56 0 19.8 0 0 0 0 52 0 1 13 19.5 0.03 9.5 1.4 1.3 0 0 118 0 20.2 0 0 0 0 120 0 2 13 19.6 0.02 9.7 1.36 0.96 0 0 105 0 20.2 0 0 0 0 105 0 0
S.Aff = severely affected
13
Table 10 Effects of fumigations with Pestigas® and ECO2FUME on Liposcelis sp., Psocidae.
Exposure time (h)
Temperature (oC)
Pyrethrum (g)
Phosphine (gm-3)
Liposcelis
Initial Final Live S.Aff Dead 15 21.1 0.02 0.56 0.42 0 0 72 0 20.5 0 0 0 81 0 2 15 18.8 0.03 1.11 0.72 0 0 98 0 20.1 0 0 0 96 0 2 15 18.2 0.02 0.64 0.45 0 0 52 0 20.3 0 0 0 54 0 0 15 20.0 0.02 1.0 0.56 0 0 113 0 20.0 0 0 0 113 0 0 15 17.7 0.03 0.63 0.53 0 0 36 0 20.1 0 0 0 36 0 0
S.Aff = severely affected Table 11 Effects of fumigations with Pestigas® and ECO2FUME on Macrosiphon rosae, Rose aphid
Exposure time (h)
Temperature oC
Pyrethrum (g)
Phosphine (gm-3)
Larvae Adults
Initial Final Live S.Aff Dead Live S.Aff Dead
15.3 20.3 0.04 0.49 0.42 0 0 241 0 4* 281 0 20.1 0 0 0 24
1 0 0 285 0 0
15 18.5 0.02 0.49 0.35 0 0 18 0 0 24 0 20.0 0 0 0 18 0 0 24 0 0 15 22.0 0.02 0.42 0.26 0 1* 29 0 0 25 0 20.1 0 0 0 30 0 0 25 0 0
S.Aff = severely affected *dead within 24 hours of fumigation
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Table 12 Effects of fumigations with Pestigas® and ECO2FUME on Orosius argentatus Common brown leafhopper
Exposure time (h)
Temperature
oC
Pyrethrum (g)
Phosphine (gm-3)
Larvae Adults
Initial Final Live S.Aff Dead Live S.Aff Dead 15 17.7 0.03 0.63 0.53 0 0 20 0 0 0 0 20.1 0 0 0 20 0 0 0 0 0 15 19.5 0.03 0.42 0.35 0 0 22 0 0 5 0 20.0 0 0 0 22 0 0 5 0 0 15 18.2 0.03 0.49 0.31 0 0 19 0 0 8 0 20.0 0 0 0 19 0 0 8 0 0
S.Aff = severely affected Table 13 Effects of fumigations with Pestigas® and ECO2FUME on Psyllid
Exposure time (h)
Temperature
oC
Pyrethrum (g)
Phosphine (gm-3)
Larvae Adults
Initial Final Live S.Aff Dead Live S.Aff Dead 15 22.2 0.04 0.95 0.86 0 0 0 0 0 8 0 22.3 0 0 0 0 0 0 8 0 0 15 17.7 0.03 0.63 0.53 0 0 6 0 0 12 0 20.1 0 0 0 6 0 0 12 0 0 15 19.5 0.03 0.42 0.35 0 0 4 0 0 7 0 20.0 0 0 0 4 0 0 7 0 0
S.Aff = severely affected Table 14 Effects of fumigations with Pestigas® and ECO2FUME on Rutherglen Bug
Exposure time (h)
Temperature
oC
Pyrethrum (g)
Phosphine (gm-3)
Larvae Adults
Initial Final Live S.Aff Dead Live S.Aff Dead
15 21.1 0.02 0.56 0.42 0 0 10 0 0 30 0 20.5 0 0 0 10 0 0 30 0 0 15 19.5 0.03 0.42 0.35 0 0 17 0 0 14 0 20.0 0 0 0 17 0 0 14 0 0 15 18.2 0.03 0.49 0.31 0 0 26 0 0 12 0 20.0 0 0 0 26 0 0 12 0 0
S.Aff = severely affected
15
Table 15 Effects of fumigations with Pestigas and ECO2FUME on White mealybug
Exposure time (h)
Temperature oC
Pyrethrum (g)
Phosphine (gm-3)
Mealybug
Initial Final Live S.Aff Dead 15 18.2 0.02 0.64 0.45 0 0 10 0 20.3 0 0 0 10 0 0 15 19.8 0.02 0.42 0.28 0 0 17 0 20.2 0 0 0 17 0 0 15 19.0 0.02 0.40 0.28 0 0 60 0 20.1 0 0 0 60 0 0 15 20.0 0.02 0.28 0.28 0 0 11 0 20.2 0 0 0 11 0 0 15 19.9 0.02 0.42 0.28 0 0 11 0 20.0 0 0 0 11 0 0 15 19.6 0.02 0.28 0.25 0 0 12 0 20.1 0 0 0 12 0 0
S.Aff = severely affected When the fumigated moth larvae M1 were assessed, about 6 hours after the treatment, they were all dead and all untreated control larvae were alive (Table 16). Unfortunately most of the control larvae died within a week and the rest died during pupation. It is hoped to obtain more larvae in the future so as to breed them to the adult stage for identification. Table 16 Effects of fumigations with Pestigas® and ECO2FUME on moth larvae (M1)
Exposure time (h)
Temperature oC
Pyrethrum (g)
Phosphine (gm-3)
Larvae
Initial Final Live S.Aff Dead 15 20.0 0.02 0.29 0.19 0 0 12 0 20.1 0 0 0 12 0 0 15 20.0 0.02 1.0 0.56 0 0 30 0 20.0 0 0 0 30 0 0
S.Aff = severely affected
16
4.2 Vase Life Experiments 4.2.1 Experiments with Bunches of Flowers and Foliage Results of vase life experiments with bunches of cut flowers over a 7 day period are given in Table 17. These results are based on observations of several bunches of fumigated and unfumigated (control) flowers kept at similar temperatures during fumigation and then observed in a "flower room" kept at 20oC. No differences in the condition of the fumigated and control flowers of the species recorded in Table 17 were noted during the observation period, with one exception. The unfumigated controls of Protea cv. Frosted Fire were in poor condition after 7 days but were in better condition than the fumigated ones that were at the end of their vase life. The yellow bells and pink myrtle were air freighted from Western Australia with their cut stems in moist potting compost enclosed in plastic bags. The flowers arrived in good condition but the journey may have affected their eventual vase life. After 7 days all the yellow bells flowers were wilting, with the exception of one unfumigated stem of Kalbarri Gold. Both fumigated and control flowers of pink myrtle were drying out after 3 days and dead and dropping after 7 days. After 7 days both fumigated and control Conospermum spp flowers were dry but they retained their colour and shape and might be considered acceptable. All the Isopogon spp buds were dry after 7days and flowers were wilting. Similarly the Eriostemon flowers were all wilting after 7 days. Only four stems of the Protea cv. Frosted Fire were available for the experiment. One stem was used as a control and the rest were fumigated. After 7 days there was extensive blackening of the leaves of the control stem and one of the fumigated stems, the other fumigated stems remained in good condition. Some of the flowers lasted for much longer than 7 days. All the banksias and queen proteas lasted for at least 14 days. The golden phylica lasted longer as did the umbrella fern and Leucadendron. Commercial fumigations of golden phylica were being carried out regularly with no ill effects being reported. The smoke bush dried out but remained attractive as the flowers retained their colour and did not fall off the stems.
17
Table 17 Effects of Fumigation on Cut Flowers and Foliage Treated with Pestigas and ECO2FUME for 15 - 16 Hours. Species of Cut Flowers/Foliage Common name Vase life observations after 1 day 3 days 7 days Acacia baileyana Good Good Some flowers
shrivelled Acacia pravissima Good Good Flowers shrivelled Acacia cultriformis Good Good Flowers shrivelled Acacia covenyi Good Good Flowers shrivelled Banksia solandri Good Good Good Banksia praemorsa (yellow) Cut-Leaf Banksia Good Good Good Boronia cv. Lipstick Good Poor End of vase life Boronia purdeana Good Poor End of vase life Conospermum caeruleum Smoke Bush Good Good Flowers dry Conospermum etoneae Good Good Flowers dry Eriostemon australasius Good Good End of vase life Eriostemon Flower Girl Good Good End of vase life Geleznowia verrucosa Yellow Bells
(Daffodil Type) Good Good End of vase life
Geleznowia verrucosa Yellow Bells (Kalbarri Gold Type)
Good Good End of vase life
Hypocalymma robustum Pink Myrtle Good Poor End of vase life Isopogon cuneata Coneflower Good Good End of vase life Isopogon latifolius Mountain Coneflower Good Good End of vase life Leucadendron Good Good Good Protea magnifica Queen Protea Good Good Good Protea Frosted Fire Good Good Fair* Phyllica plumosa Golden Phylica Good Good Good Sticherus umbellatus Fine Leaf Umbrella
Fern Good Good Good
* some leaf blackening. Most of the flowers recorded in Table 17 were fumigated for 16 hours with 0.02gm-3 of pyrethrum, an initial concentration of 0.84gm-3 of phosphine and a final concentration of 0.56gm-3. Acacia baileyana and A. pravissima were fumigated for 15 hours with 0.02gm-3 of pyrethrum, an initial concentration of 0.40gm-3 of phosphine and a final concentration of 0.36gm-3.
18
Vase life assessments for the first fumigation in which stems were separated and placed in individual tubes or jars of water for observation are given in Table 18. Observations were continued until the end of vase life or for up to 16 days. No clear differences in the vase life of fumigated and control flowers were observed. Table 18 Effects of Fumigation on Cut Flowers Treated with Pestigas and ECO2FUME for 15 Hours.
Species of cut
flowers
Common name
Vase life observations after Avearge Vase life
1 day
3 days
6 days
8 days
12 days
14 days
16 days
Actinotus helianthi
Flannel Flower
Good Good Good, but trace of brown on 3 flowers
12 of 13 stems good
6 of 13 stems good
1 of 13 stems good
End of vase life
10 days
Boronia heterophylla (STS treated)
Red Boronia
Good Good 3 of 5 stems good
End of vase life
6 days
Leucadendron
Pisa Good Good, but slight browning 2 of 8 stems
Good, but slight browning 2 of 8 stems
Good, but slight browning 2 of 8 stems
7 of 8 stems good
5 of 8 stems good
1 of 8 stems good
13-14 days*
* 1 fumigated stem was in good condition after 20 days vase life, as was also 1 control stem.
19
4.2.2 Experiments with Leptospermum Vase life assessments of fumigated Leptospermum cultivars are given in Table 19. There was some variation in the age of the harvested product assessed and there was no discernible difference between the performance of control and fumigated stems. Leptospermum cv. Lavender Queen (Longford) performed well as did Aphrodite and L. rotundifolium. The vase life of the other cultivars was shorter than desirable. Table 19 Effects of Fumigation on Leptospermum cultivars Treated with Pestigas and ECO2FUME for 15 Hours.
Leptospermum Vase life observations after Average Vase life
4 days
5 days
6 days
7 days
8 days
11 days
12 days
Aphrodite Good 16 of 19 stems good
16 of 19 stems good
13 of 19 stems good
4 of 19 stems good
2 of 19 stems good
End of vase life
7 days
Rhiannon 12 of 16 stems good
10 of 16 stems good
6 of 16 stems good
3 of 16 stems good
3 of 16 stems good
3 of 16 stems good
1 of 16 stems good
6 days
Lavender Queen (Longford)
Good Good Good Good 8 of 11 stems good
End of vase life
8 days
L. rotundifolium Good Good 5 of 6 stems good
4 of 6 stems good
2 of 6 stems good
End of vase life
6 days
L. polygalifolium Var. polygalifolium
3 of 4 stems good
3 of 4 stems good
2 of 4 stems good
End of vase life
5 days
L. turbinatum 5 of 7 stems good
5 of 7 stems good
2 of 7 stems good
End of vase life
days
4.2.3 Experiments with Waratahs Vase life observations on the fumigated waratahs are recorded in Table 20. All flowers were in reasonable condition after 7days despite some abcision of flowers and bract shrivelling. It was evident from the start that some flowers were more advanced than others all the older flowers had come to the end of their vase life after 10 days when there was extensive browning of bracts, abcision of flowers and flowers turning a deep bluish colour. The younger flowers both fumigated and controls came to the end of their vase lives after 11 days. Detailed observations were not made on the flowers other than waratahs that were exposed to fumigations with additional carbon dioxide. However, all flowers were in good condition following fumigation and there were no complaints from customers.
20
Table 20 Effects of Fumigation on Waratahs cv. Gembrook Treated with Pestigas, carbon dioxide and ECO2FUME for 13 Hours. Treatment Vase life observations after 1 day 7 days 10 days 11days Fumigated 2styles open (old) Beginning to abcise end of vase life Fumigated Good Beginning to abcise end of vase life Fumigated Good Good Fair End of vase life Fumigated Good Some bract shrivelling end of vase life Fumigated Good (old) Beginning to abcise end of vase life Fumigated 10 styles open
bracts browning(old) Beginning to abcise, Some bract shrivelling
end of vase life
Control Good (young) Good Fair End of vase life Control Good Good Fair End of vase life 4.2.4 Experiments with Thryptomene In the first Thryptomene fumigation, the bunches were assessed 1 and 8 days after completion of fumigation Table 21. There was no clear distinction between fumigated and control bunches. The condition of stems within the bunches was somewhat variable some stems were in good condition while others showed flower drop with yellowing of leaves and dryness of foliage. Bunches in which most stems were in good condition were considered worth retaining, where most stems were in poor condition the bunches were at the end of their vase lives and were discarded. Table 21 Effects of Fumigation on Thryptomene Treated with Pestigas and ECO2FUME for 15 Hours. Treatment Vase life observations after 1 day 8 days Untreated Control Bunches in good condition 1 bunch in reasonable condition, 1 bunch
at end of vase life Fumigated Flat Bunches in good condition 6 bunches in reasonable condition, 2 bunches
at end of vase life After the second Thryptomene fumigation the bunches were held in a cool room for 4 days before being transferred to the flower room and the first assessment was 6 days after completion of fumigation. At this assessment all bunches showed some signs of flower drop and some of the leaves were drying, but all were considered worth retaining. A final assessment was made 13 days after fumigation, 11 days after the end of the cold treatment. Some stems in the control bunches and in 5 of the fumigated bunches remained in reasonable condition the rest would have to be discarded as would the remaining 3 fumigated bunches (Table 22). It was suggested that separating bunches into separate stems for vase life observation might provide a better comparison of treated and untreated product.
21
Table 22 Effects of Fumigation on Thryptomene Treated with Pestigas and ECO2FUME for 15 Hours.
Treatment Vase life observations after 6 days 13 days Untreated Control 2 bunches in reasonable condition Some stems in both bunches in reasonable
condition, the rest were at end of vase life Fumigated Flat 8 bunches in reasonable condition Some stems in 5 bunches in reasonable
Condition, the rest were at end of vase life. 3 bunches at end of vase life.
Results of the third Thryptomene fumigation in which individual stems from control and fumigated bunches were compared are given in Table 23. Most stems remained in good or fair (acceptable but with some flowers dropping or closed) condition 7days after fumigation. A few of the stems that were fumigated flat were at the end of their vase life indicating that there may be a slightly shorter vase life with this treatment. The result could however relate to the larger number of stems treated in this manner. Table 23 Effects of Fumigation on Thryptomene Treated with Pestigas and ECO2FUME for 15 Hours. Treatment Vase life observations after 1 day 4 days 7 days Untreated Control 9 stems in good condition Good 8 stems good, 1 fair Fumigated in Bucket 8 stems in good condition Good 8stems good Fumigated Flat 31 stems in good condition Good 22 stems good, 6 fair, 3 end
of vase life
22
5. Discussion
The phosphine formulation ECO2FUME was used in this study because it could be readily incorporated into many existing fumigation chambers, notably those set up for use of the aerosols Pestigas and Insectigas. ECO2FUME had advantages over solid phosphine generating formulations of aluminium or magnesium phosphide in that: - (i) phosphine was released immediately into the fumigation chamber and not gradually evolved and (ii) ECO2FUME does not leave chemical residues to be disposed of after completion of a fumigation, as do solid phosphine formulations. This avoids the need to handle chemical residues, reducing the risk of exposure of workers to phosphine.
5.1. Bioassays The survival of some insects following an 8 hour fumigation with Pestigas®, carbon dioxide and ECO2FUME indicated that the exposure time was too short to give sufficient control for export consignments of flowers. When the exposure time was extended to 13 hours results obtained were much better, all stages of S. ejectana, I. purpureus and M. persicae exposed being killed within 24 hours of fumigation. In 13 hour fumigations without additional carbon dioxide some S. ejectana and M. persicae survived, indicating that the additional carbon dioxide was important for the efficacy of the treatment. Commercial fumigations at Ausflora Pacific were generally for 15 hours overnight with a combination of Pestigas and ECO2FUME. Phosphine concentrations were generally below the 700ppm (approximately 1gm-3) recommended on the label for fumigations with ECO2FUME alone. These fumigations proved effective in killing a range of insects as indicated by data in the tables in the Results section. The strain of M. persicae used in this study was more tolerant than the one used in earlier work. An exposure period of 15 hours being required for Pestigas and ECO2FUME fumigations as compared with 6 hours for the strain used previously (Williams and Muhunthan 1998). This result emphasises the importance of carrying out periodic checks to verify that the pest species occurring on the flowers are being controlled by the treatment. If survivors are found the fumigation chamber should be checked for leaks and any found should be sealed. Subsequent fumigations should be carried out using maximum dosages and exposure times recommended and phosphine concentrations should be measured at the start and finish of fumigations to verify that good fumigations are being carried out. Also temperatures should be monitored to ensure that fumigations are carried out at a minimum of 15oC (as stated on the ECO2FUME label).
5.2. Vase Life Experiments The fumigations carried out in this project extended the range of wildflowers shown to be suitable for fumigation with ECO2FUME. The vase life experiments did not identify any vase life reduction caused by the fumigations. However some flowers notably Boronia sp. had relatively short vase lives. For these species the time taken for fumigation was an important segment of vase life. It would be advantageous to develop effective management and treatment systems in the field for these species so that the need for postharvest disinfestation could be minimised and if required insecticide dips or 2 hour aerosol treatments could be used. Thryptomene fumigations demonstrated that bunches of Thryptomene can be successfully treated while lying flat provided that the foliage is liberally sprayed with water and that all stems are treated in this manner. Vase life achieved following this treatment was acceptable, but perhaps not quite as long as for stems fumigated in buckets of water.
23
6. Conclusions This study has demonstrated the effectiveness of 15 hour fumigations with Pestigas and ECO2FUME against an extended range of insect pests of wildflowers. The range of wildflowers tested and proved to be suitable for fumigating in this manner was also extended. Strategies for improving fumigant retention and distribution within a fumigation chamber were developed. Results from this study have assisted BOC Gases in obtaining an extension of registration of Phosfume to cover fumigation of cut flowers for export, and a change of name to ECO2FUME, which became effective in March 1999. The registered application conditions are a dosage of 700ppm phosphine (approximately 1gm-3) for 15 hours at a minimum temperature of 15oC. Under these conditions there was minimal damage to flowers and foliage and all test arthropods were killed with the exception that some eggs of certain arthropods, eg. two spotted mites, survived in some fumigations. Consequently the registration is for adult and larval stages, not eggs. It is noted that use in conjunction with Pestigas can reduce the phosphine concentration required. This study has contributed to a small reduction of the exposure time required from 16 to 15 hours. Further it has been demonstrated that with the inclusion of additional carbon dioxide to give a concentration of about 9 - 10% the exposure time for treatment of some pests can be reduced to 13 hours.
24
7. References Bond, E. J. (1984). Manual of fumigation for insect control. FAO Plant Production and Protection
Paper, 54: 432pp. Muhunthan, M., Williams, P. and Thorpe, G. R. (1997). Phosphine-an alternative to methyl bromide for
postharvest disinfestation of wildflowers in containers. Agricultural Engineering Australia, 26: (2) 29-33.
Robins, B. (1997). Flower suppliers have a harder row to hoe. Business Review Weekly, May 1997:
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25
8. Appendix
Items Suppliers Canary Phosphine Detector The Canary Co. Pty. Ltd.
Suite 1, 163 Burns Bay Road, Lane Cove, NSW 2066
Tel: 02 9418 6666 Fax: 02 9427 3522
Ducts and Fans Markair Components Pty. Ltd.
H.O. P.O. Box 4295 Glenways, MDC Mulgrave, VIC 3170
Tel: 03 9561 3055 Fax: 03 9561 2573
Other Office:- Sydney Fans BCB Sales and Service
(Division of Monash Electric Motors Pty. Ltd.)
P.O. Box 1469 Rosebank, MDC Clayton South, VIC 3169
Tel: 03 9546 3833 Fax: 03 9546 3356 Gas Detector Tubes Dräger Australia Pty. Ltd.
3 Ferntree Place, Notting Hill, VIC 3168
Tel: 1800 066 756 Fax: 1800 647 484
Other Offices:- Adelaide, Brisbane, Launceston, Perth, Sydney
Gaskets and Seals Tuck’s Industrial Packings and Seals Pty. Ltd.
120 Ferrars St., South Melbourne, VIC 3205
Tel: 03 9690 2577 Fax: 03 9699 2726 Gow-Mac Gas Analyser Alpha Scientific Pty. Ltd.
44 Lynbara Avenue, St. Ives, NSW 2075
Tel: 02 9449 2436 Fax: 02 9449 2436
Heaters and Thermostats Helios Electroheat Pty. Ltd.
H.O. 3-5 Freighter Rd., Moorabbin, VIC 3189
Tel: 03 9532 0211 Fax: 03 9532 2366
Other Offices:- Adelaide, Brisbane, Sydney Photovac portable GC Alltech Associates Australia Pty. Ltd.
1st Floor 852 Canterbury Road, Box Hill, VIC 3128
Tel: 03 9897 4355 Fax: 03 9897 4241 Other Offices:- Brisbane, Perth, Sydney
Tinytag Dataloggers Hastings Data Loggers
PO Box 5112, Port Macquarie, NSW 2444
Tel: 02 6581 3900 Fax: 02 6581 3988
Valves Metaval
P.O. Box 1093, Croydon, VIC 3136
Tel: 03 9761 4000 Fax: 03 9761 4006
Toll Free: 1 800 33 8135
Distributor for Challenger Butterfly Valves
