Identifying the IPM needs of the Fresh market Tomato Industry in Northern Victoria

Transcription

1 Identifying the IPM needs of the Fresh market Tomato Industry in Northern Victoria Sze Flett et a I Dept of Natural Resources and Environment Project Number: VG98150

2 VG98150 This report is published by Horticulture Australia Ltd to pass on information concerning horticultural research and development undertaken for the vegetable industry. The research contained in this report was funded by Horticulture Australia Ltd with the financial support of Northern Victoria Fresh Tomato Industry Development Committee. All expressions of opinion are not to be regarded as expressing the opinion of Horticulture Australia Ltd or any authority of the Australian Government. The Company and the Australian Government accept no responsibility for any of the opinions or the accuracy of the information contained in this report and readers should rely upon their own enquiries in making decisions concerning their own interests. ISBN Published and distributed by: Horticultural Australia Ltd Level 1 50 Carrington Street Sydney NSW 2000 Telephone: (02) Fax: (02) horticulture@horticulture.com.au Copyright 2003 Horticulture Australia

3 The Horticultural Research and Development Corporation Project VG98150 (Completion date: 30 th June 2002) Identifying the IPM needs of the Fresh Market Tomato Industry in Northern Victoria Final Report Sze Flett et al

4 Project SF97006 Principal Investigator Contact Details Project Team Dr Sze Flett NRE Tatura Private Bag 1 Ferguson Road TATURA VIC 3616 Tel: (03) Fax: (03) sze.flett(5)nre.vic.gov.au Sze Flett (10%), Cathy Mansfield (50%), Joanne Dawson (100%)-NRE Tatura Purpose of the Report This report fulfils the requirements of Horticulture Australia Limited for a final report on project VG Aims of this project were: a) To investigate the incidence and management of bacterial canker. b) To investigate current pest and disease management practices Funding Acknowledgments The researchers acknowledge the financial support for this project from Horticulture Australia Limited, Northern Victorian Fresh Tomato Industry Development Committee and the Department of Natural Resources and Environment. Date of the report November 2002 Disclaimer Any recommendations contained in this publication do not necessarily represent current HRDC policy. No person should act on the basis of the contents of this publication, whether as to matters of fact or opinion or other content, without first obtaining specific, independent professional advice in respect of the matters set out in this publication. The advice provided in this publication is intended as a source of information only. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.

5 Contents Media Summary 1 Technical Summary 2 Introduction 4 Materials and Methods 6 1. Investigating the incidence and management of bacterial canker in fresh tomatoes Bacterial Canker Survey Bacterial Canker - development and implementation of disease management strategies 6 2. Investigating current pest and disease management practices of the fresh market tomato industry Incidence and impact of tomato pests, diseases and beneficials Monitoring Level of parasitism of Helicoverpa in fresh tomato crops Harvest assessments 8 3. Developing a Helicoverpa monitoring technique for the fresh tomato industry Chemical usage in the fresh market tomato industry Current chemical use and its affects on pests and diseases Resistance testing on Helicoverpa Preliminary Targeted Chemical trial 11 Results Investigating the incidence and management of bacterial canker on fresh market tomatoes Bacterial Canker Survey Bacterial Canker - development and implementation of disease management strategies Investigating current pest and disease management... practices of the fresh market tomato industry Incidence and impact of tomato pests, diseases and beneficials Pests Diseases Beneficials Physiological and nutritional disorders Overview of fruit damage from harvest assessments Developing a Helicoverpa monitoring technique for the fresh tomato industry Chemical Usage in the fresh market tomato industry Current chemical use and its affects on pests and disease Resistance testing on Helicoverpa Preliminary targeted chemical trial 23 Discussion 24 Technology Transfer 27 Recommendations 29 Acknowledgments 30 Appendices 31 Appendix 1 32 Bacterial Canker Report 32

6 Media Summary The Victorian fresh tomato industry currently relies on routine chemical applications to maintain a high quality product. However, in order to meet consumer demands for 'clean, green' blemish free products, for both domestic and export markets, the industry is keen to explore the potential of Integrated Pest Management (IPM). This project was conducted to provide baseline data on pests and diseases in fresh market crops and quantifying the associated fruit loss, which are essential for the development of an effective IPM strategy. Studies on the parasitism of Helicoverpa by the parasitic wasp Trichogramma were also conducted. Our results showed that up to 50% of the Helicoverpa was parasitised during the growing season. This project investigated current grower practices to control pests and diseases and their impact on yields and pest pressures. Results showed that current practices could lead to increased risk of insecticide resistance developing in Helicoverpa (otherwise known as Tomato Grub). Our research suggests that modification of current practices, including improved timing of chemical applications to target pests when they are in high numbers and at the most susceptible stage of the life cycle may maximise pest control and ensure long term environmental sustainability. This project emphasises the need for grower awareness of pest and disease monitoring as a tool to target control measures to minimise crop damage. To promote industry awareness of the project outcomes nine presentations and two workshops were conducted betweenl999 and Two posters aimed at providing a pictorial guide to tomato pests and diseases were developed and distributed to all growers. Based on the findings of this project, a new project titled 'Integrated crop management of fresh market tomatoes', project VX02013, will commence in October

7 Technical Summary The Victorian fresh market tomato industry does not currently practice Integrated Pest Management (IPM). Spray programs based on routine chemical apphcations, every 7-10 days, are used to manage pests and diseases in this industry. This practice results in unnecessary spray applications and misses key insecticide application windows leading to an increase in production costs and high fruit damage. IPM uses a range of techniques to effectively control pests and diseases. A variety of biological, chemical and cultural methods provide growers with more options for controlling pests and diseases than their current spray programs. To successfully manage pests and diseases, information is needed on the key pests and diseases, their pressures and the level of fruit damage, current chemical usage and the levels of beneficial insects. The project obtained information by monitoring tomato crops, harvest assessments and by assessing chemical spray records for timing of chemical applications and effectiveness of those applications in reducing pest numbers. The primary pest in fresh market crops was Helicoverpa. As only a few tomato crops were monitored each season the full impact of secondary pests may not have been observed. Secondary pests may have been more of a problem in other tomato crops. The other pests found were thrips, leafhoppers, aphids and mites. The main disease problem was bacterial canker. Other disease problems were powdery mildew, big bud, bacterial speck and tomato spotted wilt virus. Other disorders such as scarring, blossom end rot, zippering and catface may cause up to 19% fruit damage at harvest. This project found gaps in growers spray programs, which coincided with high oviposition by Helicoverpa. Helicoverpa needs to be targeted at its most vulnerable stage, ie the first instar larvae. For growers to target this vulnerable life stage, they need to be monitoring the crops. Improving the timing of chemical applications would improve the impact of chemical applications on pest populations. Growers' spray records also showed that the same chemical group was being applied over several generations of Helicoverpa. This practice can lead to the development of Helicoverpa resistance to insecticides. A preliminary study on resistance in Helicoverpa was undertaken in this project. Resistance testing of Helicoverpa caterpillars to two commonly used chemical groups, pyrethroids and carbamates, was conducted. In the laboratory, there was Helicoverpa resistance to both of these commonly used chemical groups. Resistance was demonstrated when Helicoverpa was sprayed with insecticides from these chemical groups at doses that usually cause mortality in Helicoverpa. In order for growers to reduce the risk of resistance problems arising in the future they need to change the way they spray so that they are rotating groups of chemicals and not just brand names. This project also showed that at the peak in Trichogramma populations, up to 60% of Helicoverpa eggs were parasitised. If growers used less broadspectrum chemicals and more targeted chemicals (pest specific chemicals), particularly at the start of the season when Trichogramma populations are building up, this may result in higher parasitism levels over the whole season. This project has shown that more work is needed in resistance management to prevent the development of resistance in Helicoverpa and other pests by reducing the use of broadspectrum insecticides and including a wider range of products, for example, targeted chemicals. More work is also needed on timing and crop management strategies to improve timing and efficacy of chemicals and preserve natural biological controls. 2

8 Future IPM work in the Victorian fresh market tomato industry should focus on following: 1. Development of Helicoverpa Resistance Management Strategies 2. Studies to improve our understanding of Helicoverpa migration and its impact on resistance in the Northern Irrigation Region 3. Timing of chemical applications and Crop Management Strategies Timing and efficacy trials Primary pest specific chemical trials 3

9 Introduction The Victorian fresh market tomato industry is a small industry, which produces high value crops. The industry is comprised of 30 growers that produce 45,000 tonnes of fresh tomatoes on 400ha, with an approximate annual farm gate value of $50 million. There is increasing consumer pressure for products that are 'clean and green', that is, grown with minimal chemical use and environmental impact. This is not only becoming increasingly apparent in the local market but many international markets have strict guidelines for chemical use and chemical residues. One of the priorities set by the Northern Victorian Fresh Tomato Industry Development Committee was gaining access to Asian markets. An IPM strategy adopted by the industry will help the fresh market industry achieve some of its export goals. In the Victorian fresh market tomato industry, pest management decisions are currently based on routine calendar spray programs with 7-10 day intervals. These spray programs are neither efficient nor environmentally sustainable methods of pest control. Currently, there are no documented strategies on Integrated Pest Management (IPM) for the fresh market tomato industry in northern Victoria. For growers to successfully manage pests and diseases in a responsible and safe manner that meets market and quality assurance standards, information is needed on the key pests and diseases, their pressures and level of fruit damage, current chemical usage and the levels of beneficials. Market research undertaken in the late 90's indicated that there was a lack of industry knowledge on the economic impact of pests and diseases and the exact level of damage caused by different pests and diseases. There was also an indication from growers that IPM could be beneficial to the industry. Ms Jean Bentley conducted a market research analysis (Project TM97004) to examine the potential development of IPM for the fresh market tomato industry. In this survey, growers indicated that the most important pest was Helicoverpa followed by mites and the most common disease problems were bacterial speck and powdery mildew. However, the exact level of damage, and its economic significance was not known. In addition, many growers were uncertain of the differences between diseases and this may result in the use of inappropriate sprays for their control. Growers scheduled their chemical applications by the calender, spraying their crops every 7-10 days, which may result in unnecessary applications. This survey also indicated that the two main barriers to IPM adoption by the fresh tomato growers were (a) that growers felt that it was too risky to use less chemicals, and (b) growers wanted to learn more about IPM before employing an IPM consultant. Growers did, however, acknowledge that there are potential benefits of using IPM in their business. In addition to Bentley's survey, a serious outbreak of disease in all tomato crops in 1999 emphasised the need for industry wide adoption of IPM. In early February 1999, the presence of bacterial canker was confirmed in fresh tomato crops in the Goulburn Valley. This disease is caused by the bacterium Clavibacter michiganensis subsp. michiganensis (Cmm). The disease was severe in some early plantings, resulting in some blocks being abandoned, ie. not harvested. Department of Natural Resources and Environment staff conducted a survey for the Northern Victorian Fresh Tomato Industry Development Committee during February and March The purpose of the survey was to determine the extent and severity of the disease, and to identify any correlation of disease with tomato variety, crop management and paddock history. The bacterial canker outbreak clearly demonstrated the need to regularly monitor crops for pests and diseases. IPM strategies and crop monitoring are used extensively by the Queensland fresh market tomato industry and by the processing tomato industry. However, both industries are 4

10 different in many ways from the Victorian fresh market industry. Hence IPM programs developed for the processing industry and for the Queensland fresh market industry cannot be directly adopted by the Victorian fresh market tomato industry. The Queensland fresh market tomato industry has more economically important pests such as potato moth, silverleaf white fly and Queensland fruit fly which are not major pests in Victoria. The cropping season runs over 10 months compared to 7 months in the Victorian industry. Finally, the Queensland industry has an established culture of crop monitoring since 1980 (Dale Abbott, personal communication). Significant fruit damage (up to 50% losses) caused by the potato moth has led to the adoption of IPM in Bundaberg. In Bowen, growers approached the University of Queensland to monitor their crops to improve the timing of their spray applications. Fresh market tomato growers in Queensland value the benefits of crop monitoring and are willing to pay crop scouts for the service. Crop monitoring and the use of IPM strategies successfully controlled potato moth in tomato crops in Queensland. The processing tomato industry based in northern Victoria and southern NSW adopted IPM in Extensive research spanning a decade within this industry has shown that precise monitoring systems, sound knowledge of beneficial insects, their biology and the use of targeted pesticides can reduce the number of chemical applications (Final report TM201). One of the IPM strategies used by the processing industry is crop monitoring. However, these monitoring techniques are not transferable to the fresh market industry because the fresh market industry is largely grown on trellis whilst processing tomatoes are ground crops. Spraying to thresholds is another strategy used by the processing industry. Processing tomato thresholds are not directly transferable to the fresh market industry because the processing industry can tolerate a higher level of damage than the fresh market which must produce blemish free fruit. The processing industry also conducted detailed studies on the parasitism of Helicoverpa by the parasitic wasp Trichogramma. The methods used to record parasitism in commercial processing tomato crops were also used in this fresh market tomato project. The processing industry also conducted field trials on releasing Trichogramma sp. nr brassicae into tomato crops to boost the early season level of parasitism of eggs. Results from final report TM201 showed that the mass release of parasitic wasps had no significant effect on the level of egg parasitism in the crop. The differences in crop management (trellis systems in fresh market), varieties (gourmet varieties in fresh market) and the requirement for high quality blemish free fruit for the fresh market, make the direct adoption of processing tomato IPM programs a high risk option. It is timely to commence the development of IPM strategies for the northern Victorian fresh market tomato industry, particularly with increasing grower interest in pest and disease management for products that meet consumer requirements. This research project is aimed at Investigating the incidence and management of bacterial canker, and, Investigating current pest and disease management practices A widely adopted IPM strategy will help to provide a more sustainable industry, current practices are environmentally adverse and will eventually lead to resistance to many of the chemicals currently available. Tomatoes grown under an IPM strategy would make use of all available control methods cultural, chemical and biological to provide a strategy which targets key pests and diseases and has less impact on the environment. This report presents results of the incidence and impact of pests, diseases and beneficials found in fresh market crops, preliminary results of chemical practices and resistance testing, results from the bacterial canker survey and management strategies for bacterial canker. 5

11 Materials and Methods 1. Investigating the incidence and management of bacterial canker in fresh tomatoes 1.1 Bacterial Canker Survey In early February 1999, a disease was reported in tomato crops in northern Victoria. The disease was confirmed to be bacterial canker of tomatoes, caused by the bacterium Clavibacter michiganensis subsp. michiganensis (Cmm). The incidence of the disease was reported to be widespread and caused serious concerns to the fresh and processing tomato industries. As part of Project VG98150, staff from the Department of Natural Resources and Environment conducted a survey for the Northern Victorian Fresh Tomato Industry Development Committee during February and March The purpose of the survey was to: Determine the extent and severity of the disease, and, Identify any correlation of disease with tomato variety, crop management and paddock history. Detailed description of the survey methodology and survey results were reported to HAL and the industry in a special report (Appendix 1) as part of milestone Bacterial Canker - development and implementation of disease management strategies Industry reviewed the project and requested that only brochures were prepared. Strategies for managing Bacterial Canker were developed and sent to growers. As part of the development of these strategies, literature on this disease (overseas and Australian) was reviewed. Two bacterial canker newsletters were published with information on the disease and options for disease management as well as the methods for reducing risks of infection. In addition, a Research-To-Practice Workshop on IPM in Fresh Tomatoes was conducted at Tatura by DNRE staff, Robin Fitz-Gerald (IK Caldwell) and Brian Walker (Tomato Consultant) on 1 st September 1999 for the industry. This workshop highlighted the need of a holistic approach to the management of pests and diseases (including bacterial canker). 6

12 2. Investigating current pest and disease management practices of the fresh market tomato industry To develop an effective IPM strategy for the fresh market industry, a range of basic information was needed. These included: a) the incidence and impact of pests, diseases and beneficials, and, b) current grower practices for the management of pests and diseases The aims of the following studies are to, over three growing seasons: 1) identify and document the range of pests and diseases affecting fresh tomato crops 2) determine the level of parasitism in Helicoverpa, and, 3) determine the level of fruit damage associated with current grower practices 2.1 Incidence and impact of tomato pests, diseases and beneficials Over the three years of this project, a total of 15 sites were monitored for pests, diseases and beneficials. Table 1 lists the location of monitored sites and crop type for each season. The monitored sites were located in Murchison, Ardmona, Mooroopna and Undera. Both trellis and ground crops were monitored. The monitoring technique was developed with a biometrician and modified at the start of each season to refine the technique. The same monitoring technique was used on both ground and trellis crops. Table 1. Location of blocks and type of crop grown (trellis or ground) Block Year Location of blocks Type of crop 1 1 Undera Ground 2 1 Mooroopna Trellis 3 1 Ardmona Ground 4 2 Undera Ground 5 2 Ardmona Ground 6 2 Murchinson Trellis 7 2 Murchinson Trellis 8 2 Murchinson Trellis 9 2 Ardmona Trellis 10 3 Undera Ground 11 3 Ardmona Ground 12 3 Murchinson Trellis 13 3 Murchinson Trellis 14 3 Murchinson Trellis 15 3 Murchinson Trellis Incidence and impact of pests, diseases and beneficials was determined by monitoring, determining levels of parasitism of Helicoverpa and by harvest assessment to determine fruit damage at harvest Monitoring Season (Year 1) Three blocks, located in Undera, Mooroopna and Ardmona, were monitored in the first season. Each block consisted of approximately 3.2ha (8 acres) of tomatoes and were monitored once a week. Two ground crops and one trellis crop was monitored. At each block, six rows were randomly selected. In each row, two plants were monitored at 20 metre intervals; this occurred at ten sites along the row. Monitoring consisted of the examination of 7

13 a whole plant for a range of pests, diseases and beneficials. The numbers of all pests and beneficials per sample were noted and the presence/absence of diseases was also recorded. All Helicoverpa eggs were collected to determine the percentage of parasitised eggs (refer to section 2.12: methodology on parasitism of Helicoverpa). All sites were monitored from November to late January Season (Year 2) Six blocks, located in Undera, Ardmona and Murchison were monitored in the second season. Six blocks of approximately 8 acres were monitored once a week. Four trellis and two ground crops were monitored. To determine sites for monitoring, row numbers and sampling distance along the rows were decided using a random number generator, twenty random sampling sites along each row were selected and monitored with a total of 6 rows monitored. All beneficials, diseases and pests other than Helicoverpa were recorded as present or absent. The first three fully expanded leaves were monitored for Helicoverpa eggs. Also actual numbers of Helicoverpa caterpillars were recorded. In this season, later planted crops were monitored from December to February Season (Year 3) Six blocks, located in Undera, Ardmona and Murchison were monitored in the third season. The method is the same as for the season except that flowers were also monitored for Helicoverpa eggs and the size and number of caterpillars was recorded. Unlike the previous two seasons, blocks were monitored twice a week Level of parasitism of Helicoverpa in fresh tomato crops Trichogramma is a parasitic wasp, which lays its eggs inside the eggs of a host species. The adult Trichogramma emerges from these parasitised eggs. Helicoverpa is a host for Trichogramma. Parasitism in Helicoverpa was estimated for each season using a method developed for the processing tomato industry (Final report TM201). All leaves with Helicoverpa eggs were collected in plastic bags. In the laboratory, the eggs were removed from the leaves and individually placed into multi-welled microtitre trays, covered with sticky tape and left at room temperature to hatch. Collection of Helicoverpa eggs occurred every week during the first two seasons of this study and twice weekly in the third season. Helicoverpa caterpillars hatched within 5-7 days after collection and Trichogramma hatched within 5-7 days after this. A single Helicoverpa caterpillar will hatch from a single egg whilst 1-6 Trichogramma will hatch from a single egg. The number of hatched Helicoverpa and Trichogramma were counted under a microscope. To determine the level of parasitism efficacy: Parasitism efficacy = hatched Trichogramma I (total hatched eggs (Helicoverpa + x 100 Trichogramma) Non viable eggs, ie. those that did not hatch, were not included in this calculation 2.13 Harvest assessments There has been no previous documentation of fruit damage at harvest using current growers' practices in fresh market crops. This project investigated the level of fruit damage due to pests, diseases and other causes by conducting harvest assessments just prior to first fruit harvest. A total of 1,200 pieces of fruit were checked at each site, recording for each fruit whether it was healthy (blemish free) or damaged. Damage fruit was recorded as Scarring, Zippering, Anthracnose, Bacterial Canker, Blossom end rot, Alternaria, Bacterial Speck, Helicoverpa, Pinhole, Catface, Black Mould rot, Sunscald, Tomato Spotted Wilt Virus or Growth Cracks. 8

14 Season (Year 1) Rows were chosen based on the same row selection process as described in the monitoring technique for the season. Two adjoining rows were checked and 20 fruit per sampling site were examined for a range of possible damage causes Season (Year 2) & Season (Year 3) Rows were chosen based on the same row selection process as mentioned in the monitoring technique for the season. There were 20 sample sites along each row with 20 fruit checked at each site. 9

15 3. Developing a Helicoverpa monitoring technique for the fresh tomato industry To ensure that monitoring is most accurate, Helicoverpa eggs need to be monitored where the majority of eggs are laid. For example, the processing tomato industry monitors the third fully expanded leaf on ground tomatoes, as this is where most of the Helicoverpa oviposition (egg lay) occurs. To investigate the accuracy of this method on tomato crops (ground and trellis) grown for the fresh market, a study was conducted in the season to determine the relevance of leaf position within the plant to oviposition. During the monitoring of Helicoverpa in season, Helicoverpa egg numbers and the position of the leaf where the eggs were laid was recorded (counting leaf numbers from the first fully expanded compound leaf at the top of the plant). Statistical analysis using a generalised linear model with Poisson errors applied to the leaf position data was used to formulate the monitoring technique for the following season. 10

16 4. Chemical usage in the fresh market tomato industry In the northern Victorian fresh market tomato industry, the effectiveness of current chemical programs used by growers has not previously been examined. It is important to understand the implications of the pest and disease management decisions to determine if methods could be adjusted to improve pest and disease control and efficiency of chemical applications. To improve our understanding of current chemical practices and their implications the following studies were conducted: (a) Examination of chemical use records of the fresh market tomato growers, (b) Resistance testing, and, (c) Preliminary trials of chemicals targeted toward specific pests. 4.1 Current chemical use and its affects on pests and diseases Chemical records were collected from the 15 blocks that were monitored to understand current management practices in relation to chemical use. The patterns of chemical groups being used throughout the growing season were examined to provid an assessment of growers' chemical programs. The chemical records and Helicoverpa monitoring were compared to determine if timing of insecticide applications was consistent with peaks in Helicoverpa oviposition. 4.2 Resistance testing on Helicoverpa Helicoverpa resistance to carbamates and pyrethriods has been observed on a number of different crops grown throughout Australia. Southern New South Wales has implemented a resistance management strategy for Helicoverpa. Resistance testing in the fresh market tomato industry for Helicoverpa has not previously been undertaken. It is important to understand the insecticide resistance status of Helicoverpa in Victorian fresh market tomato crops. Preliminary investigations into the potential resistance of Helicoverpa spp. to two groups of commonly used chemicals were conducted. Helicoverpa larvae were collected and sent to Robin Gunning, NSW AG Tamworth, for resistance testing using the methodology described by Gunning et al 1992 and Anon The larvae were tested for resistance to carbamates and pyrethroids. Resistance factor (RF) for fenvalerate (pyrethroid) indicates the amount of insecticide required to kill the Helicoverpa we collected compared to the susceptible laboratory strain of Helicoverpa. 4.3 Preliminary Targeted Chemical trial New chemicals with different impacts on the environment and new chemistry have recently entered the market with potential for improved IPM in tomato crops. David Morey of DC Caldwell established a preliminary trial at Murchison during the season. The trial aimed to compare (1) the impact of fruit damage at harvest of a conventional spray program with one that uses a targeted chemical program and (2) the impact on Trichogramma populations. The first chemical used at the targeted chemical block was chosen by the grower for its broadspectrum effects this was applied once at crop establishment. David Morey chose the other two chemicals used because they were new chemistry and have not been used extensively in tomato crops. Targeted chemicals aim to control just the specific pest, such as Helicoverpa caterpillars, their impact on other organisms is minimal. Individual chemicals were not tested only chemical programs were tested in this trial. A comparison of a targeted chemical program and conventional chemical program provided a preliminary indication of the effectiveness of a targeted chemical program. The trial was on two adjacent blocks at the one site and chemicals were applied on the same day at both blocks. Each block was monitored for Helicoverpa egg numbers and Trichogramma parasitism. A harvest assessment was undertaken to determine in the impact of Helicoverpa on fruit damage. This was not a replicated trial. 11

17 Results 1. Investigating the incidence and management of bacterial canker on fresh market tomatoes 1.1 Bacterial Canker Survey Refer to Appendix 1 for the full report on Bacterial Canker 1.2 Bacterial Canker - development and implementation of disease management strategies 'Best Bet Risk Management for Tomato Growers' brochures were sent to all fresh market tomato growers. 12

18 2. Investigating current pest and disease management practices of the fresh market tomato industry 2.1 Incidence and impact of tomato pests, diseases and beneficials (monitoring data, harvest assessments and parasitism) 2.11 Pests Pests found in fresh market tomato crops were: Helicoverpa, Aphids, Thrips, Looper, Brown Leaf Hopper, Green Leaf Hopper, Mites, Rutherglen Bugs and White Fly. Helicoverpa eggs and caterpillars were recorded as actual numbers, while all other pests were recorded as present or absent. While the percentage of plants infested was high for some pests, the actual numbers of the pest present may not have been high. High infestation can be more of a problem with some pests, such as thrips and brown leaf hopper, which transmit disease. Helicoverpa Our monitoring showed that Helicoverpa is the primary pest species of fresh market tomatoes, it caused the most damage to fruit during the three years of monitoring. In year 1, early planted crops (blocks 1-3), the fruit damage at harvest ranged from 1.3% to 6.9% and at peak egg lay up to 182 eggs were laid. In year 2, late-planted crops (blocks 4-8), the fruit damage at harvest ranged from 3.9% to 18.2% and at peak egg lay up to 130 eggs were laid. In year 3, early-planted crops (blocks 9-15), the fruit damage at harvest ranged from 0.25% to 1.67% and at peak egg lay up to 327 eggs were laid. The total number of eggs laid during a season does not have a direct correlation to the fruit damage by Helicoverpa at the end of the season. Table 2 Peak egg lay for Helicoverpa and fruit damage caused by Helicoverpa Block Peak number of eggs laid atone time Range of egg numbers laid during monitoring to to to to to to 130 unknow n to to to to to to to to to Fruit Damage % Harvest Assessments 13

19 Blocks Year 1 (monitored once a week from November to January) Blocks Year 2 (monitored once a week from December to February) Blocks Year 3 (monitored twice a week from December to February) Secondary pests Secondary pests did not have a significant influence on the development of the crop or fruit damage during the seasons we monitored. The percentage of plants infested with secondary pests varied between pests and between the monitoring years (Table 3). Table 3 Range of% tomato plants with pest present found in fresh market tomato crops during monitoring % plants with pest present Pest Yearl Year 2 Year 3 Aphids 21.3 to to to 71.7 Thrips 0 to to to 30.8 Mites 0 to Rutherglen bugs 0to55 0 to to 36.7 Loopers to 2.5 Brown leaf hopper 0to50 0 to to 10.8 Green leaf hopper 0 to to to 6.7 White flies 0 to to 2.5 0to5 Figure 1 Calender of pest occurrence over the duration of the project (averaged per fortnight over 3 years of project) 14

20 ; The calender shows the number for pests per fortnight averaged, with high numbers greater than 25% above the average and low numbers 25% lower below the average. For Helicoverpa the average of egg numbers were used. For all other pests the average of the number of plants with the pest present (%) was used. KEY H High numbers (25% greater than average) Average Low numbers (25% less than average) Tomatoes not monitored during this period No tomatoes in the ground PESTS Helicoverpa Aphids Thrips Rutherglen Bugs Brown leaf hopper Green leaf hopper SEP OCT '' f. Nov 1st 15th ills Nov 16th - 30th :. Dec 1st 15th Dec ISth 30th Jan 1st - 15th Jan 16th- 30th Feb 1st 15th :... '(i ' j ; l..: :. * flfcatl. : j White Fly V,,H Feb 16th - 30th MAR APR MAY JUN JUL AUG > 4 ' ' \ i Mi. 1 l k : :i '$'.? ***..* -i - A ': :: ": ;.- *' ": /* - -, ' 11 * * ' " Diseases Diseases found in fresh market tomato crops were: Bacterial Canker, Powdery Mildew, Bacterial Speck, Tomato Spotted Wilt Virus, Big Bud, Anthracnose and Alternaria 15

21 Some of the disease found including powdery mildew and big bud affect plant health and vigour. Other diseases in the crop including bacterial canker, bacterial speck and tomato spotted wilt virus can directly affect the fruit and therefore directly reduce marketable yield. Bacterial canker A serious outbreak of bacterial canker occurred in the season. During this time many tomato growers had significant losses, some growers lost 50% of their crop (Appendix 1). In the following season ( ), bacterial canker was still a problem for some growers (causing 8.1% of fruit damage)(table 4). Bacterial canker was not a problem for the crops monitored in this project in subsequent seasons. Secondary diseases Secondary diseases generally caused only low damage as recorded at harvest (table 5). However, a high number of plants were affected by powdery mildew in year 1 (table 4). The prevalence of both big bud and tomato spotted wilt virus is dependent on the presence of insect vectors that spread those diseases. Favourable conditions for any of these diseases could lead to a greater impact on fresh market tomato crops in the future Table 4 Range of disease incidence in fresh market tomato crops in the 3yrs of the project % plants with disease present Disease Yearl Year 2 Year 3 Bacterial Canker 0 to Bacterial Speck 0to20 0 to 0.8 0to15 Powdery Mildew 0to50 0 to to 43.3 Tomato spotted wilt virus 0 to to 1.7 Big Bud 0 0 to to 0.8 Table 5 Fruit damage (%) at harvest assessment for diseases % damaged fruit at harvest Disease Yearl Year 2 Year 3 Anthracnose 0 to to Bacterial Canker 0 to Bacterial Speck 0 0 to to Beneficials Beneficials found in fresh market tomato crops were; Trichogramma wasp, Hover flies, Lacewings, Assassin Bugs, Other parasitic wasps, Spiders and Parasitised Aphids Most beneficials were not seen consistently throughout the season, but only occasionally and only in low numbers. 16

22 Trichogramma Trichogramma numbers varied greatly throughout the season and between properties. At the start of the season (for most blocks) there was no parasitism. At the peak of parasitism the level was up to 59% (Table 6). Some crops had no parasitism at all and others had very little, less than 10%. Table 6 Level of Trichogramma parasitism of Helicoverpa eggs Block Peak Parasitism % Average Parasitism % Range of Parasitism % to to to to to to to to to to to to to 59.5 Blocks Year 1 (monitored once a week from November to January) Blocks Year 2 (monitored once a week from December to February) Blocks Year 3 (monitored twice a week from December to February) Other beneficials: Of all the general predators present in the crops monitored, spiders were found most consistently and were also the most numerous (Table 7). Spiders are likely to prey on a range of the pest species present. There was a higher occurrence of spiders at the start of monitoring with numbers declining over the monitoring period. A range of other beneficials was found but in low numbers, (table 7). Establishment of beneficials is affected by the availability of a food source, availability of hosts, weather conditions and chemical applications. 17

23 Table 7 Incidence of benefwials in fresh market tomato crops during the project % plants with beneficiais present Beneficiais Yearl Year 2 Year 3 Spiders 1.7 to to to 11.7 Hover fly 0 to to 0.8 Parasitised Aphids 0 to to 0.8 Lacewings 0to5 0 to to 2.5 Wasps 0to10 0 to to 2.5 Assassin Bugs 0 to to to 1.7 Ladybirds 0 0 to Physiological and nutritional disorders Disorders found in fresh market tomato crops included: Blossom end rot, Scarring, Zippering, Catface, Sunscald and Cracking. Crops were only monitored for pests, diseases and beneficiais through the season. Disorders such as pollination problems, rubbing on wire, damage through wind and rain and nutritional problems were only assessed during the harvest assessment. Our results show that these disorders may cause high fruit damage (affecting fruit quality) up to 19% for an individual disorder (Table 8). Table 8 Fruit damage (%) recorded in harvest assessments- proportion of fruit damaged in total from 1200 pieces of fruit assessed Fruit Damage %at Harvest Assessment Disease Yearl Year 2 Year 3 Blossom end rot 0to11 0 to to 2.8 Zippering 0.3 to to to 4.9 Scarring 3.5 to to to 10.5 Catface 0 to to to 1.4 Sunscald 0 to to to 0.25 Growth Cracks 0 to to to Overview of fruit damage from harvest assessments The following graphs show only damaged fruit and excludes healthy fruit (marketable fruit)(figure 2). These graphs illustrate seasonal variation in the cause of fruit damage. The impact of the primary pest Helicoverpa was variable, ranging from 6% to 58% of all damaged fruit. The other major causes of fruit damage were the physiological disorders scarring and zippering, the nutritional disorder blossom end rot and the disease bacterial canker. 18

24 Figure 2 Proportion of damaged fruit affected by pests, diseases or physiological disorders at harvest during seasons (a) , (b) , (c) (a> lesslhan 1% less than 1% 3% 2% than 1% H Black mould rot M Catface Blossom end rot D Growth cracks B Heliothis ss% Scarring BSunscald ^_ DZippering (b) D Bacterial Speck less than 11 19% E Bacterial Canker D Blossom End Rot Scarring Sunscald B Catface D Growth Cracks 44% D Black Mould V_ ^J (C) 24% lesslhan 1% less lhan 19 Q Bacterial Speck I 6% IS Catface ^ D Blossom end rot D Growth cracks B Heliothis 10% B Scarring % Q Possible heliothis DZippering 19

25 3. Developing a Helicoverpa monitoring technique for the fresh tomato industry The first year's monitoring results showed that leaf numbers 1, 2 and 3 were the highest subset of leaves for Helicoverpa eggs (p=0.05), ie the highest number of Helicoverpa eggs were found on leaves 1, 2 and 3. There was no significant difference between the number of Helicoverpa eggs found on leaves 1, 2 and 3 (p>0.05). Table 9 Leaf position data - Number of Helicoverpa eggs found on leaves 1-10 Leaf numbers are counted from thefirstfully expanded compound leaf at the top of the plant Leaf number Block 1 Block 2 Block

26 4. Chemical Usage in the fresh market tomato industry 4.1 Current chemical use and its affects on pests and disease Timing of insecticide sprays Crops were monitored from December to February and all monitoring results were reported to participating growers the day after monitoring the block. However, spray records often gaps in their spray programs, when peaks in egg numbers occurred. Intervals between chemical applications ranged from 1 day to 49 days during the season. Our data shows that Helicoverpa eggs will hatch in mid January and the larvae will be protected inside the plant before the critical sprays are applied. Typically, the spray records of participating growers indicate that chemicals have not been applied to align with critical oviposition periods. Figure 5 The mean Helicoverpa oviposition during a tomato season from the week after planting to the week of harvest on a property in the Goulburn Valley. Arrows indicate key insecticide application times. Current insecticide programs Growers used a range of insecticides to control pests in their tomato crops and mainly relied on insecticides from the pyrethriod, organophosphate and carbamate groups (Table 10). There is limited grower use of new chemicals, such as spinosad and indoxacarb. These new chemicals are targeted for specific pests and are known to be less harmful to beneficials. Growers used insecticides from the same chemical group for several applications during the season (Table 11). Often chemical programs included the application of two or more insecticides at the same time and these insecticides were likely to have been combined in the spray vat. It is also common practice to apply fungicides at the same time as insecticides. Primarily insecticide applications were targeted to control Helicoverpa. There are a number of examples where repetitive applications of the same type of chemical occurred over the different generations of Helicoverpa. The number and frequency of insecticide applications was quite variable between growers and between seasons. Table 10. Insecticides used by participating growers during the project 21

27 Insecticides Group Components Chemical type Nudrin 1A Methomyl Carbamate Lavin 1A Thiodicarb Carbamate Azodrin IB Monocrotophos Organophosphate Rogor IB Dimethoate Organophosphate Nitofol IB Methamidophos Organophosphate Endosulfan 2A Endosulfan Cyclodienes Miti-fol 2B Dicofol Polychlorocycloalthanes Kelthane 2B Dicofol Polychlorocycloalthanes Scud 3A Cypermethrin Pyrethroid & Pyrethrins Bulldock 3A Beta-cyfluthrin Pyrethroid & Pyrethrins Sumi-Alpha 3A Esfenvalerate Pyrethroid & Pyrethrins Hallmark 3A Esfenvalerate Pyrethroid & Pyrethrins Fastac 3A Alpha-cypermethrin Pyrethroid & Pyrethrins Ballistic 3A Deltamethrin Pyrethroid & Pyrethrins Talstar 3A Bifenthrin Pyrethroid & Pyrethrins Success 5A Spinosad Spinosyns Vertimec 6A Abamectin Avermectin, Emamectin, Benzoate Avatar 22A Indoxacarb Indoxacarb Table 11. Examples of the current insecticide programs showing the chemical groups used and the number of applications of each chemical group. Insecticide Spray application number Program 1 Program 2 Program 3 Program 4 Program 5 Program 6 Program 7 Program 8 1 IB.3A 3A 1B 1A.5A 1A 1B 1B 1B, 3A 1B 2 IB.3A 1B.3A 2A 5A 3A, 1A 3A 1B, 3A 2A 3 IB.3A 1A.1B 1B 1A,1B,2A 6A 3A 1B, 1A, 22A 3A 4 IB.3A 2A 3A 1A,1B,2A 1B 3A 3A 3A 5 1A.1B.3A 2A 3A 1A,1B,2A 3A 1B, 1A, 3A 5A 6 1B,1B,3A 1A.5A 1A.1B 1B, 1A, 3A 2B 7 1A.1B.2A 6A(mites) 1A.1B 1B, 1A, 5A 3A 8 1A.2A 1A.1B 1B, 1A, 3A 3A 9 2A 1A.3A 22A 2B 10 1A.1B.3A 1B, 1A, 3A 3A 11 1A.5A 1A, 3A 4.2 Resistance testing on Helicoverpa Results from resistance testing showed that there was resistance developing in Helicoverpa (in northern Victorian fresh market tomatoes) to some commonly used chemicals (carbamates and pyrethroids). Results of laboratory testing show that the pyrethroid resistance factor (RF) is 32. This means the RF is relatively high in the Goulburn Valley, RF 15 or less is acceptable. Some carbamate resistance was present so only 40% were killed compared to a susceptible strain. The level of resistance suggests that even small larvae would not be killed by field rates of carbamates. 100% of the population was resistant to pyrethroids and 40% of the population was resistant to carbamates. 22

28 Table 12 Results from resistance testing ofhelicoverpa Site Pyrethroid Pyrethroid Carbarmate resistance resistance resistance (fenvalerate) factor (RF) (thiodicarb) Resistance% Resistance% Tatura Preliminary targeted chemical trial This trial compared two different chemical strategies for their effects on beneficials and efficacy of the program: (a) Targeted (pest specific) strategy, and, (b) Conventional strategy - grower's current spray programs. The trial was assessed by observing the parasitic wasp Trichogramma and its effectiveness in controlling Helicoverpa, and its impact on parasitism of Helicoverpa. At the peak of Helicoverpa parasitism during the season, there was a noticeable difference between the percentage of Helicoverpa eggs parasitised in the block using a targeted chemical regime and the average of the blocks using a conventional chemical regime. At the peak of parasitism in the targeted chemical block 52% of Helicoverpa eggs were parasitised, in the conventional block an average of 11% of Helicoverpa eggs were parasitised, with blocks varying between 0% and 30%parasitism. There was also a difference in the level of fruit damage at harvest caused by Helicoverpa in the conventional block which had 4% higher fruit damage compared to the targeted chemical block (Figure 6). These results were not replicated and cannot be statistically analysed. Figure 6- The proportion of fruit damage caused by Helicoverpa in a preliminary targeted chemical block and a conventional block adjacent to each other. % Fruit damage caused by Helicoverpa 1'- re 6 - E... D m 4 3 uz 3.. * Targeted Chemical Block - - i Conventional Chemical Block 1 uheliothis 23

29 Discussion This project investigated (1) the incidence and impact of pests, diseases and beneficials (2) incidence and management of bacterial canker and (3) current chemical use. It was undertaken to understand the impact of current pest and disease management practices and to identify opportunities for maximising pest control and long term industry sustainability. Crop monitoring is an essential element of IPM, providing information on pests, diseases and beneficials present in crops. This information assists growers to evaluate the risks associated with these pests and diseases and make appropriate management decisions. Effective and timely pest control decisions can only be made with regular monitoring. For ease of monitoring a common monitoring technique which could be used in both trellis and ground crops was required. Trellis crops have a different growth habit with a more open canopy than ground crops so we had to use a monitoring technique that would work on both types of crops. From the first year's monitoring results we found that the first three fully expanded leaves had the highest egg oviposition on the plant, with no significant difference between these three leaves. This information was used to develop our monitoring technique for the remaining years of the project. A comparison between egg numbers and spray records indicate that growers, whilst provided with egg lay numbers in the crop, did not use these results when making spray application decisions. Limited monitoring services are provided free of charge by the local chemical resellers in Northern Victoria. Chemical resellers rely on a mix of pheromone trapping and scouting to determine what is present in the crop. This study identified Helicoverpa spp. as the primary pest of tomatoes. Helicoverpa is also a primary pest in the Victorian tomato processing industry (Final report TM201), a common problem in the Queensland fresh market industry (Final report VG95009), and a large number of other host plants (Zalucki et al 1986). When asked how much Helicoverpa damage growers in the fresh market industry are willing to sustain in their crops, growers commonly answer zero or less than 1% damage. It was, therefore, important to establish what levels of fruit damage they currently had under a conventional spray program. With fruit damage levels caused by Helicoverpa up to 18% and averaging 10% for all growers, growers should question whether their current control methods are cost effective and sustainable even in the short term. In , Helicoverpa damage levels were considerably lower than the previous year ( ) although there were still large gaps in spray programs at critical times. This difference may be due to cooler weather conditions, which slow the development of Helicoverpa. Helicoverpa oviposition also seemed to be at similar levels to the previous year ( ) when damage was much higher than the 2001/2002 season. Lower Helicoverpa damage may have been influenced by the unusually cool climate conditions, which may have slowed Helicoverpa population development and increased natural mortality rates. The total number of eggs laid by Helicoverpa did not correlate to the fruit damage caused by Helicoverpa. This indicates that fruit damage is influenced by factors other than the number of eggs laid in the crop. These other factors could include natural mortality, weather conditions, insecticide programs, predation and parasitism. Bacterial canker was the main disease problem. Bacterial canker was found in the years after the 1999 outbreak. However in the monitored blocks the impact of this disease was minimal. The bacterial canker outbreak emphasised the need to monitor crops as early detection may prevent the losses seen in the season. The outbreak also emphasised the need for good hygiene practices that could prevent inoculum from entering the crops. Results on the bacterial canker survey are in the attached report on bacterial canker Appendix 1. Climatic conditions vary considerably during the cropping season. The crops monitored were those under the most pressure from Helicoverpa, other crops planted at other times during the season may be exposed to different climatic conditions and have a greater problem with 24

30 diseases or secondary pests. For example mites and powdery mildew become a problem in many crops towards the end of the six week harvest period, however this is not reflected in our data as monitoring finished before the start of harvest. Secondary pests and diseases found were similar to those found in processing crops, such as; leafhoppers, aphids, thrips, mites, rutherglen bugs, powdery mildew, bacterial speck, tomato spotted wilt virus and big bud. Secondary pests and diseases may cause fruit loss or damage or have an impact on the plants through loss of vigour or reduction in fruit set. Loopers, Rutherglen bug and thrips can cause direct damage to fruit. Thrips, brown leafhoppers and aphids are all vectors for diseases, and may be controlled to reduce the potential impact of disease, rather than due to the direct damage they cause on the crop. Diseases such as tomato spotted wilt virus, bacterial canker and bacterial speck can directly affect the fruit reducing marketable yield. Favourable conditions for any of the secondary pests and diseases could lead to a greater impact on fresh market crops in the future. Parasitoids are known to be susceptible to broad-spectrum insecticides and a range of broadspectrum insecticides is commonly used in crops in Northern Victoria. Parasitoid populations need time to build up naturally. If their population is heavily sprayed, they will not reach population levels that could assist in the control of Helicoverpa. If growers wish to increase parasitism in their crops they would need to reduce broad-spectrum insecticides especially early in the season as the Trichogramma numbers build. Parasitism will not be able to control Helicoverpa under current chemical spray programs. In parasitism levels were higher than in previous years. This could be due to a range of factors such as reduced migration of Helicoverpa, Trichogramma resistance to insecticides or favourable climatic conditions. Spiders were found in the highest number of all the beneficials. The occurrence of spiders decreased over the monitoring period indicating that repetitive spraying may reduce numbers over time. Spiders are general predators and are likely to feed on a number of insects in the crops including larvae. Spiders have also been observed preying on Helicoverpa eggs (Knutson 2002). Other predators and parasites were found in small numbers. A pest management strategy, which allowed beneficial populations to build up numbers, would see these beneficials having a greater impact on pest numbers. There are a number of opportunities for improvement of current chemical programs, including using crop monitoring to time spray applications, rotating chemical groups and spraying only one insecticide at a time rather than cocktails of chemicals. For chemicals to be effective against a pest they should be applied at the most vulnerable lifestage of the pest. Ideally, Helicoverpa should be targeted while it is a first instar larva. Growers need to monitor their crops to see peaks in Helicoverpa oviposition and when eggs hatch so they can target the vulnerable lifestages. If growers are not monitoring their crops they will not be able to maximise the impact of their chemical applications. As Helicoverpa larvae develop they enter the tomato plant where they are protected from chemical applications. In summer eggs can be laid, then hatch and the larvae can be protected inside the plant within 7 days, which based on current chemical spray programs could all happen between insecticide applications. Long gaps in the spray program are fine if very few eggs are being laid however if there are peaks in oviposition during this time they can develop unhindered and cause fruit damage. Large larvae (over 2cm) are often very visible to the grower in the crop however once larvae reach this size, chemical applications are often ineffective as the damage has already been done and larvae are hard to kill. Monitoring crops will also allow some indication of the success of chemical controls. Preliminary resistance testing of Helicoverpa collected in the Goulburn valley indicated that there was resistance to two of the main chemical groups used to control Helicoverpa, pyrethroids and carbamates. If these chemicals are not used effectively resistance may continue to develop. Some insecticide programs examined during this project utilise the same 25

31 chemical group(s) throughout the season. This will most likely lead to resistance developing as there is a constant genetic selection pressure on pests, which reduces the numbers of susceptible individuals in the population and increases the number of resistant individuals. Monitoring crops to ensure the minimum number of sprays are applied at the most susceptible life stage, applying recommended rates, rotating chemical groups and applying a good spray coverage and cultural practices such as cultivating soon after harvest can reduce the selection pressure on target pests (McDougall 2000). Growers need a better understanding of chemicals and the impact of brands, chemical groups and repeated use on resistance. The Victorian fresh market tomato will incur significant fruit losses if chemical sprays become ineffective due to resistance. 26

32 Technology Transfer Posters, Bacterial Canker Brochures and handouts for growers are available upon request. Handouts for Growers Project folders handed out for 99/00 season and 00/01 season Laminated handouts on the Lifecycle of Helicoverpa Laminated Photos / reference sheets on pests, diseases, beneficials and other disorders Poster Dawson, J, Flett, S., Mansfield C. (2002). Poster on pests, diseases and beneficials in fresh market crops - distributed by mail to the fresh market tomato growers October 2002 Dawson, J, Flett, S., Mansfield C. (2002). Poster on Helicoverpa (Tomato Grub) life cycle - distributed by mail to the fresh market tomato growers October 2002 Articles Mansfield, C. (1999). IPM in fresh tomato team. Red gold newsletter Mansfield, C. (2000). What insect pests & diseases did you have in your tomato crop this season. Red gold newsletter, April Dawson, J. (2000). Tomato Red gold newsletter, July Mansfield, C. (2000). What is happening to my crop. Red gold newsletter, December Dawson, J. (2001) Identifying the IPM needs of the fresh market tomato industry in Northern Victoria (VG98150) - Key Results / Achievements. Report for Hort news - May 2001 Bacterial Canker Brochures Best Bet Management for Tomato Growers. NRE Bacterial Canker brochure Edition 1, 1999 Best Bet Management for Tomato Growers. NRE Bacterial Canker brochure Edition2, Autumn/Winter, 1999 Best Bet Management for Tomato Growers. NRE Bacterial Canker brochure Edition 3 Summer, 2000 Workshops Fresh Market Tomato growers IPM research to practice workshop, Venue NRE Tatura. 1 st September 1999 Fresh Market Tomato growers Heliothis workshop, Venue: NRE Tatura. 15 th February 2001 Conferences Mansfield, C, Dawson, J., Hepworth, G. (2000) Poster presentation at the Entomology Conference, Darwin June 2000 Mansfield, C, Dawson, J., Hepworth, G. (2000) NRE Horticulture 2000 Conference - September 2000 Annual / Biennial reports Flett, S., Mansfield, C, Dawson, J. Identifying the IPM needs of the fresh market tomato industry in Northern Victoria. Institute of Sustainable Irrigated Agriculture Annual Report. Department of Natural Resources and Environment. 27

33 Flett, S., Mansfield, C, Dawson, J. Identifying the IPM needs of the fresh market tomato industry in Northern Victoria. Institute of Sustainable Irrigated Agriculture Review. Department of Natural Resources and Environment. Presentations to growers Results of bacterial canker survey reported to the FTIDC -June 1999 IPM fresh market tomato steering committee - August 1999 AGM fresh tomato industry - June 2000 FTIDC meeting to discuss research priorities - August 2000 FTEDC meeting to discuss 00/01 results, next seasons work and possible future work - May 2001 FTEDC meeting - September 2001 Steering committee meeting - September 2001 FTEDC meeting - June 2002 AGM fresh tomato industry - June

34 Recommendations This project demonstrated that Helicoverpa populations in fresh market crops in Northern Victoria were resistant to pyrethroid and carbamate resistant populations are also developing. The frequency of carbamate resistant genes suggests that a resistant management strategy is urgently required. Any resistant management strategy will have to address grower lack of knowledge and understanding of chemical mode of action, chemical groupings, and the appropriate stages in pest phenology at which to use particular chemical treatments. Growers also need a better understanding of how to effectively utilise parasitiod and predators and integrate chemical use into such biological systems. Further work is need to develop: Resistance Management Strategies for Helicoverpa Resistance testing Helicoverpa migration studies Resistance management strategy and Improve timing of chemical applications and Crop Management Strategies Primary pest specific chemical trials Timing and Efficacy trials Record keeping 29

35 Acknowledgments The project team would like to acknowledge the contributions of steering committee: Brian Walker, Dave Morey, Robin FitzGerald, Tony Mercuri, Ilhan Tanrikulu, Frank Rossignuolo, Peter Ridland, Liz Minchinton, Jane Moran. Joe Vraca, Ilhan and Ayhan Tanrikulu, Ray Eren, Frank Rossignuolo & sons and Albert Borzillo supplied sites. Leigh Callinan and Graham Hepworth (Biometricians) and Annabelle Simson, Debbie Dellar, Rocky Pelligrino, Lucinda Gibson, Aysun Tanrikulu and Jill White provided technical services. Roger Ashburner provided support and advice and Robin Gunning conducted the resistance testing. 30

36 Appendices 31

37 Table of Contents Table of Contents 0 Disclaimer 1 Acknowledgement 1 EXECUTIVE SUMMARY 2 SURVEY STAFF INTRODUCTION MATERIALS AND METHODS Survey area Survey method Laboratory diagnosis Remote sensing technology for disease assessment Statistical analysis RESULTS & DISCUSSION Presence of bacterial canker Factors associated with field infection and bacterial canker diagnosis CONCLUSION REFERENCES ; 13 0

38 Disclaimer Any recommendations contained in this publication do not necessarily represent current HRDC policy. No person should act on the basis of the contents of this publication, whether as to matters of fact or opinion or other content, without first obtaining specific, independent professional advice in respect of the matters set out in this publication. This publication may be of assistance to you but the State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication. Acknowledgement This survey was funded by the Department of Natural Resources and Environment (DNRE) and the Horticultural Research and Development Corporation (HRDC) with the funding source from the Northern Victorian Fresh Tomato Industry Development Committee (NVFTIDC). 1

39 EXECUTIVE SUMMARY In early February 1999, a disease was reported in tomato crops in northern Victoria. The disease was confirmed to be bacterial canker of tomatoes, caused by the bacterium Clavibacter michiganensis subsp. michiganensis (Cmm). The incidence of the disease was reported to be widespread and caused serious concerns to the fresh and processing tomato industries. A Canker Task Team, comprising of growers and processors from the fresh and processing tomato industries and Department of Natural Resources and Environment (DNRE) staff, was established to coordinate the dissemination of information and activities related to the outbreak. A survey was conducted by DNRE staff for the Northern Victorian Fresh Tomato Industry Development Committee during February and March The purpose of the survey, as noted by the Canker Task Team (February 1999), was to: determine the extent and severity of the disease, and, identify any correlation of disease with tomato variety, crop management and paddock history A survey protocol, originally designed for a bacterial canker survey for the processing tomato industry in 1999, was applied to fresh tomatoes. A total of 132 blocks from 21 commercial properties with reported or possible presence of bacterial canker were included in the survey. Those properties represented more than 80% of the fresh tomato production in Victoria. Our analysis of the data showed that the field assessment was not a reliable method for detecting plants affected by Cmm. Therefore, all statistical analyses were restricted to the 91 blocks for which a laboratory diagnosis was made. The survey showed that 85.7% of the tomato varieties surveyed were affected by bacterial canker. The bacteria (Cmm) were confirmed to be present in 81.3% samples sent for laboratory diagnosis. Cmm was detected in 95% of blocks planted with the most commonly planted vine trained variety, Daniela. The survey also showed that Daniela had a significantly greater proportion of blocks that were diagnosed positive for bacterial canker, than the other sampled varieties combined. However, factors including vine training and crop location were also associated with the positive laboratory diagnosis of bacterial canker. Ninety-five percent of the vine trained blocks were diagnosed positive for bacterial canker whereas only 53% of bush tomato blocks were affected by disease. Effects of these factors on the disease could not be separated from the effects for variety, Daniela. Factors such as planting date, sharing of equipment or the presence of a tomato crop in the same paddock in the previous year did not have an effect on the presence of bacterial canker. 2

40 SURVEY STAFF Institute of Sustainable Irrigated Agriculture Tatura Sze Flett Bill Ashcroft Colin Aumann Joanne Dawson Wendy Guppy Ramez Aldaoud Leigh Callinan (Biometrician) Institute for Horticultural Development Knoxfield Elizabeth Minchinton 3

41 1.0 INTRODUCTION Bacterial canker of tomatoes, caused by the bacterium Clavibacter michiganensis subsp. michiganensis (Cmm), is not a new disease in southern Australia. Based on anecdotal evidence and herbarium records (total of 22 records of Cmm from New South Wales, Queensland, South Australia and Victoria), bacterial canker has been detected sporadically in tomato crops (Minchinton et al., 1998). More recently, bacterial canker was reported near Leeton (New South Wales) in February 1996, and in Barooga (NSW) during the season (Anon., 1998). The disease is systemic, ie., the bacteria live inside the host and affect all parts of the tomato plant. In early February 1999, the presence of bacterial canker was confirmed in fresh tomato crops in the Goulburn Valley. The disease was severe in some early plantings, resulting in some blocks being abandoned, ie., not harvested. During this same period, crop scouts in Victoria reported widespread symptoms of a disease on processing tomato crops. This disease was later identified as bacterial canker (Minchinton, et al., 1999). Following this outbreak, a survey was initiated by the Australian Processing Tomato Research Council (APTRC) to identify practices conducive to the disease. The disease was confirmed to be widespread in processing tomato crops (Minchinton, et al., 1999). A Canker Task Team, comprising growers and processors from the fresh and processing tomato industries and Department of Natural Resources and Environment (DNRE) staff, was established as a consequence of the outbreak. The Canker Task Team provided a forum for discussion on the disease and its implications for industry. In addition, it played a key role in the coordination and dissemination of information to industry, government and the media as well as the coordination of activities related to the outbreak. Following discussions with the Canker Task Team, a survey similar to the one initiated by the APTRC for the processing industry, was conducted by DNRE staff for the Northern Victorian Fresh Tomato Industry Development Committee (NVFTIDC) during February and March The purpose of the survey, as for the processing tomato industry, was to: determine the extent and severity of the disease, and, identify any correlation of disease with tomato variety, crop management and paddock history This paper reports the outcomes of the bacterial canker survey in the fresh tomato industry in Northern Victoria. 4

42 2.0 MATERIALS AND METHODS 2.1 Survey area All fresh market tomato-growing districts in northern Victoria were surveyed, including Tatura, Ardmona, Mooroopna, Arcadia, Undera, Byrneside, Lancaster, Harston, Murchison, Nagambie and Bridgewater. A total of 132 blocks from 21 commercial growers representing more than 80% of fresh tomato production were surveyed. Growers were selected on the basis of known or possible presence of the disease on their farms. Of the blocks surveyed, 69 were planted with the variety Daniela, 17 with Waratah and 46 with a range of other varieties including Arcadia, Boss 707, Early Peel, FA 593, Italian Pride, Lana, Marutschka, Marzano, Mercedes, Roma, SPS-942 and Triumph. A block is defined as one planting date, on one property, under one management system, usually comprising of a single variety and is often under separate control for irrigation. 2.2 Survey method The protocol developed by the APTRC survey team, as described by Minchinton et al. (1999), was used. Tomato properties were visited and all blocks on the property were surveyed using a "walk through" method. When the survey crew moved into a new paddock, boots, equipment and hands were washed and disinfected. Canker hotspots were recorded on the property map for future reference. In particular, the survey team looked for symptoms of the disease, which included: brown patches within the block (Fig. 1A) brown and/yellowing leaves (Fig. 1B) leaves with brown margins and yellow halos around the lesions wilt or dieback of whole plants spotting on fruit (Fig. 2)

43 Figure 2. Bird's eye spots caused by Cmm on green fruit (left) and ripe fruit (right). Approximately pieces (a composite sample) of tomato leaves and fruit with suspected symptoms of bacterial canker were randomly collected from each surveyed block. Samples were taken from a total of 91 blocks for laboratory tests at Crop Health Services (CHS), Knoxfield, to determine the presence of the bacterium, Cmm. In the field, severity of canker symptoms in each planting was rated as: 1 =trace, 2=low, 3=moderate and 4=severe. 0=none, 2.3 Laboratory diagnosis Isolation of bacteria and pathogenicity tests The isolation and identification of Cmm was conducted by CHS, Knoxfield, using culturing methods. Under sterile conditions, samples of diseased tomato tissue were coarsely macerated in sterile distilled water and examined for 'bacterial ooze'. The macerate was streaked onto King's B medium as described by Thomas and Rodoni (1999). Colonies that resemble Cmm were sub-cultured onto nutrient agar and gram positive coryneforms were inoculated onto tomato seedlings (cv. Floridade) at the two true leaf stage for pathogenicity testing. The presence of Cmm in the tomato sample was confirmed by its correct identification on agar culture and its ability to cause canker disease in the greenhouse pathogenicity test. 2.4 Remote sensing technology for disease assessment The assessment of disease is a very important but difficult task in the study of disease epidemics (epidemiology). The survey method described above for bacterial canker is based on the field detection of disease (qualitative) and laboratory detection for Cmm (definitive). The methods for field disease assessments are time-consuming, laborious, lack precision and repeatability. To avoid these problems, other technologies have been employed elsewhere to measure plant disease outbreaks (Campbell and Madden, 1990). One such method is the use of remote sensing technology for the detection and estimation of plant disease severity. The 1999 bacterial canker outbreak offered an opportunity to explore improved methods for future disease assessments and, potentially, disease monitoring and prediction. With the expertise of the Geographical Information Systems (GIS) Group at ISIA, Tatura, 6

44 the use of digital infrared imagery was suggested as a worthwhile technique for the assessments of future bacterial canker outbreaks. Airborne images of 3 fresh tomato properties were taken in March on a scale of 1:10,000 using Colour Infra Red Kodak 2443 film in 2 flight runs by a Melbourne-based company, United Photo and Graphics Services P/L. The digitised infrared photographs provided images in 3 layers of spectral information - infrared, red and green wavelengths. These images are currently being processed to: Develop a quantitative measure based on the infrared and red intensities to qualify field observation rankings of disease severity across the tomato blocks; Calibrate field observation rankings using within-block variations of infrared and red intensities; and, Map the disease pattern across all blocks of observations using a composite index based on infrared and red intensities. This sub-component of the bacterial canker survey is not completed to date, and will be an on-going part of the HRDC Project on IPM in Fresh Tomatoes (VG98150). Results of this sub-component do not impact on the results of the field and laboratory bacterial canker diagnoses. 2.5 Statistical analysis Data (variables) recorded in the survey were field and laboratory diagnosis of bacterial canker, tomato variety, location, planting date, vine training, nursery origin, shared equipment, use of phosphite fungicide and previous crop (ie. prior to current tomato crop). The significance of associations between pairs of these variables was determined by x 2 analyses or by Fisher's Exact Test. Data were statistically analysed using Genstat Lawes Agricultural Trust (Rothamsted Experimental Station). Some variables (including weather events and use of phosphite fungicide) were not statistically analysed because the required data set was incomplete. 7

45 3.0 RESULTS & DISCUSSION 3.1 Presence of bacterial canker The bacterium (Cmm) was confirmed to be present in 72 of the 91 samples (79%) sent for laboratory diagnosis. Laboratory diagnoses also confirmed the presence of Cmm on a sample each of capsicum and the weed, blackberry nightshade. The association between the field and laboratory diagnosis of bacterial canker is shown in Table 1. Table 1. Numbers of blocks affected by bacterial canker as confirmed by field and laboratory diagnosis Field diagnosis A Laboratory diagnosis - ve + ve - ve ve 2 70 A Two blocks were not diagnosed in the field but samples from these blocks were diagnosed -ve in the laboratory. The laboratory test is considered definitive for bacterial canker. The sensitivity (ie., the ability to detect a diseased plant) in the field assessment was % (95% confidence limits). The specificity of the field assessment (ie., the ability to detect a healthy plant) was %. Due to the low reliability demonstrated for the field assessment, all further analyses were restricted to the 91 blocks for which a laboratory diagnosis was made. 3.2 Factors associated with field infection and bacterial canker diagnosis Most of the tomato blocks (56/91= 62%) were planted with the variety, Daniela (Table 2) This variety had a greater (p<0.001) proportion of blocks (53/56 = 95%) diagnosed positive for bacterial canker, than the other varieties combined (16/35 = 46%). The next most common variety was Waratah (9 blocks). A greater (p<0.01) proportion of Daniela blocks was diagnosed positive for bacterial canker, than for Waratah blocks (5/9 = 56%). The effects of 'variety' on bacterial canker cannot be separated from the effects of 'location'. Forty of the 56 Daniela blocks in this analysis were from one location. Thirtyeight of these 40 blocks were diagnosed positive for bacterial canker. When blocks from this location were removed from the analysis, there was still had a greater proportion of Daniela blocks diagnosed positive for bacterial canker, than either blocks of other combined varieties (p<0.01) or the variety, Waratah (p=0.04). 8

46 Table 2. Numbers of blocks by tomato variety and laboratory bacterial canker diagnosis Tomato variety Laboratory diagnosis -ve +ve FA Arcadia 2 4 Boss Daniela 3 53 Early Peel 0 1 Italian Pride 2 0 Lana 0 1 Marutschka 0 1 Mercedes 0 1 Marzano 1 1 Roma 3 2 SPS Triumph 2 0 Waratah 4 5 The analysis is unable to separate the effects of variety from vine training (ie., trellising). All Daniela blocks were vine trained, whereas only one of 35 blocks of the other varieties was vine trained (Table 3). Vine training involves the intensive handling of transplants including pruning, tipping, tying and clipping. These activities will enhance the spread of Cmm (Farley, et al., 1973; Gleason et al., 1993), particularly if the diseases were not detected early. Table 3. Numbers of blocks by variety and vine training Tomato variety Vine training No Yes FA Arcadia 6 0 Boss Daniela 0 56 Early Peel 1 0 Italian Pride 2 0 Lana 1 0 Marutschka 1 0 Mercedes 1 0 Marzano 2 0 Roma 5 0 SPS Triumph 2 0 Waratah 8 1 9

47 Proportionally more of the vine trained blocks (54/57 = 95%) were affected by bacterial canker than the untrained blocks (18/34 = 53%) (p<0.001) (Table 4). Table 4. Numbers of blocks by laboratory bacterial canker diagnosis and vine training Vine trained Laboratory diagnosis No Yes - ve ve All Daniela plants were raised at either Barooga and/or Boomaroo nurseries. There were no differences between these two nurseries in bacterial canker incidence. The proportion of bacterial canker positive Daniela blocks that originated from Barooga was 9/9 (100%), that for Boomaroo was 32/33 (97%). The presence of bacterial canker was not associated (p>0.27) with planting date, sharing of equipment, or the presence of a tomato crop in the same paddock in the previous year. 3.3 Remote sensing technology for disease assessment Airborne images of fresh tomato crops in the Murchison area are as shown in Fig. 3, 4 and 5. Figure 3. Digital infrared image of a fresh tomato crop (bush) near Murchison. 10

48 Figure 4. Digital infrared image of a fresh tomato crop (trellis) affected by bacterial canker at Wahring. Figure 5. Digital infrared aerial image of a fresh tomato crop (trellis) affected bv bacterial canker at Murchison. 11