Review of integrated pest management options for Wales

Transcription

1 Review of integrated pest management options for Wales Prepared for: Dave Thomas Prepared by: Sarah Wynn ADAS UK Ltd Approved by: Susan Twining ADAS UK Ltd Date: March 2014 Co-authors: Dr.Steve Ellis (arable pests), Dr.Sarah Cook (weeds), Dr.Gemma Hough (Horticultural weeds), Tim Boor (disease), Rebecca Carter (PGRs), Charles Bentley (amenity) and Chris Creed (Welsh Horticulture). FINAL

2 Executive Summary Background The Sustainable Use Directive requires that pesticide users take actions to minimise the use of pesticides on their crops through the implementation of Integrated Pest Management (IPM) methods on their farms. The Welsh Government needs information about the available IPM methods, the ease of adoption and effectiveness in order for them to develop appropriate policy to meet the needs of the Sustainable Use Directive. This report sets out the main IPM options available for the main pesticide uses in Wales for agriculture, horticulture and the amenity sector, analyses their current adoption and factors that affect adoption. A National Action Plan for the Sustainable Use of Pesticides 1 (covering the whole of the UK) was published in February 2013, setting out how the principles of IPM should be implemented by all professional users by January The National Action Plan highlights that it is important that pesticide users take a sophisticated and well-informed risk-based approach to managing pests, weeds and diseases, supported by advice from agronomists and industry guidance. Under the National Action Plan for the Sustainable Use of Pesticides the Welsh Government has to encourage the adoption of low input regimes, including Integrated Pest Management (IPM) using risk indicators, and monitor progress towards a reduction in pesticide use. Methodology This report is based on a desk exercise where specialists in weeds, pests, disease and growth regulation in different sectors, identified the IPM methods available in Wales, through published literature, experience and local knowledge of pesticide practices in Wales. The report focuses on the IPM methods used in nine sectors that use pesticides: grassland, forage crops, cereals, break crops, root crops, vegetable crops, fruit, and amenity. The analysis is presented under four key areas: 1. Identification of current IPM methods for the key crops grown in Wales; 2. Assessment of selected IPM methods based on a defined set of criteria including current adoption, current supporting evidence, availability of supporting advice, ease of adoption and identification of key gaps and uncertainties; 3. Categorisation of methods based on their adoption level and supporting evidence; 4. Recommendations for the Welsh Government to inform policy development. Results Adoption of IPM methods is modest across the arable sector, where scale, economics and availability of pesticides encourage farmers to take the easiest/quickest option which is often just to treat with a pesticide. IPM adoption is good in the grassland and amenity sectors, where IPM is predominantly focused towards weed control and driven by lack of available pesticides. Adoption of IPM methods is high in the horticultural sector, with use of pest and disease monitoring, thresholds, resistant varieties and storage hygiene widely adopted as means to reduce pesticide use. High levels of adoption in this sector are largely driven by market pressure for high quality crops, with low pesticide residues and lack of available pesticides. There are a range of factors that influence uptake of IPM methods including market drivers such as requirements from buyers and farm assurance, cost-effectiveness, availability of information and advice and quality and availability of supporting evidence. Methods with i

3 market pull, and good information and advice that are also low cost to implement, tend to be adopted more widely. Methods where the cost-effectiveness is questioned or there is a need for specialist machinery, skills or knowledge are less well adopted. Conclusions and recommendations Current status of IPM adoption: Adoption of IPM methods is moderate across the arable sector. There are a number of IPM methods that are already widely used in arable crops as part of standard farming practice; such as cultivations, crop rotation, delayed drilling and variety resistance. However, this sector has the potential for wider adoption of often relatively cost effective and easy to implement IPM methods, such as spray thresholds. Farmers need to develop trust in these thresholds and understand how to get the best from them in order to increase adoption. Given that the arable sector accounts for 79,461ha of the Welsh utilised agricultural area and has moderate pesticide usage (averaging around 4 kg/ha in wheat over the season), the potential to reducing total pesticide usage is greatest in this sector. IPM adoption is good in the grassland, often as a result of land being either inaccessible for spraying or farmers lacking appropriate machinery for pesticide application. The majority of IPM methods in grassland are focused towards weed control, although the number and type of IPM methods adopted does vary depending on location and topography. In grassland mowing/topping/grazing and variety choice are the most commonly selected IPM methods and are widely adopted within this sector. IPM adoption is also high in the amenity sector, driven predominantly by a lack of available pesticides and also bystander safety. Methods adopted by the amenity sector focus primarily on weed control and include mowing, hand weeding and thermal destruction of weeds using hot air or steam. IPM adoption is high in the horticulture sector, often with more advanced IPM methods being adopted compared to the other sectors such as routine use of pest monitoring, disease forecasting, use of beneficial insects and use of thresholds. The driver behind adoption in horticulture is in part market pressures from supermarkets and consumers requiring high quality produce with low pesticide inputs, but also by a lack of approved pesticides. Certain horticultural situations, such as protected cropping, lend themselves well to the use of certain IPM methods such as the introduction of predators / beneficial insects. Pesticide usage can be very high in certain horticultural crops such as strawberries, averaging 54 kg/ha active substance in soil grown strawberry crops, however the area of horticultural crops in Wales is just 1,449 ha. There are already industry drivers aimed at reducing pesticide usage in horticulture and therefore due to the relatively high levels of adoption to date, small area and other pressures driving adoption of IPM, horticulture is not considered to be a high priority for government intervention, instead it is classified as medium priority. Priorities for encouraging increased adoption: High Priority - Improving IPM uptake in the arable crop. Pesticide usage is significant in this sector, there are few market drivers, and adoption of IPM is currently limited to the easy to adopt methods. Improving scientific evidence behind threshold models, supporting farmers/agronomists to use online disease forecasting tools, mechanical weeding and promoting cover crops are priorities to encourage IPM use in the arable sector. ii

4 Table ES 1 IPM methods to target to increase IPM uptake in Wales ranked in order of priority, including barriers to adoption and methods to overcome barriers to adoption in the arable sector IPM method ranked in order of priority (1= highest) Barriers to adoption Methods to overcome barriers 1) Promote use of pest thresholds prior to deciding to spray Lack of clear information available; thresholds based on anecdotal rather than scientific evidence, thresholds out of date and low cost of insecticides. Fund research into pest thresholds used to make management decisions for key pests such as OWBM or pollen beetle. Educate farmers on benefit of using pest thresholds, rather than insecticides to reduce insurance insecticide sprays being used. 2) Live (real time) monitoring and guidance Lack of awareness that live monitoring is available and the fact that monitoring data must be used in conjunction with expert advice. Industry engagement and promotion of live monitoring and guidance tools available. Education of agronomists in where to access and how to use the tools available. 3) Mechanical weeding High cost, requires trained operator, may cause crop damage and needs appropriate soil conditions to work appropriately. 4) Cover crops High costs of seed, preparation of seedbed and destruction, poor establishment. Further research on applicability of mechanical weeding in arable farming system. Educate growers on the benefits of using mechanical weeding through farmer workshops or industry engagement. Educate growers on benefits of cover crops for weed control. To support the increased adoption of pest thresholds there is the potential to develop clear guidance on thresholds for different pests. This will involve two stages, with the first stage focusing on further research into pest thresholds to support or disprove the current pest thresholds in place as many thresholds were developed over twenty years ago and so may not always be applicable to current varieties or were based on anecdotal evidence rather than robust scientific investigation. The second stage should focus on knowledge transfer of this information to farmers to increase confidence in using pest thresholds to guide spray decisions. Examples of knowledge transfer mechanisms include knowledge dissemination through Farming Connect advisors and the Farming Connect website, promotion of training schemes iii

5 such as BASIS and sprayer operator training, and use of demonstration farms to highlight the practical benefits of IPM to farmers. Medium Priority Supporting IPM adoption in the horticulture sector. This sector currently has the highest use of pesticides per hectare compared to the arable, grassland and amenity sectors, however current uptake of IPM methods in this sector is high due to pressure from market drivers. Further research and communication of research findings regarding exploiting beneficial organisms and biological control options to growers should be considered. Table ES 2 IPM methods to target to increase IPM uptake in Wales ranked in order of priority, including barriers to adoption and methods to overcome barriers to adoption in the horticulture sector IPM method ranked in order of priority (1= highest) Barriers to adoption Methods to overcome barriers 1) Exploit beneficial organisms and biological control Growers need help and advice to move from using chemicals to IPM systems. 2) Resistant varieties Lack of independent information and the drive for crop quality over disease resistance. Educate individuals providing advice to growers on the benefits of exploiting beneficial organisms and biological control, which situations to use this IPM method in and likely effect on pest levels. Independent research into resistant characteristics of varieties. Communication of research findings with growers to inform management decisions. 3) Live (real time) monitoring and guidance Lack of awareness that live monitoring is available and the fact that monitoring data must be used in conjunction with expert advice. Industry engagement and promotion of live monitoring and guidance tools available. Education of agronomists in where to access and how to use the tools available. 4) Promote use of pest thresholds prior to deciding to spray Lack of clear information available; thresholds based on anecdotal rather than scientific evidence, thresholds out of date and low cost of insecticides. Fund research into pest thresholds used to make management decisions for key pests such as thrips and Codling moth. Educate farmers on benefit of using pest thresholds rather than insecticides to reduce insurance insecticide sprays being used. iv

6 IPM method ranked in order of priority (1= highest) Barriers to adoption Methods to overcome barriers 5) Mechanical weeding High cost, requires trained operator, may cause crop damage, needs appropriate soil conditions Educate growers on the benefits of using mechanical weeding through farmer workshops or industry engagement. Low Priority - Encouraging uptake of IPM methods in the grassland sector. Pesticide usage is relatively low in this sector and adoption of best practice methods, such as mowing/topping and varietal use to control diseases is good. Table ES 3 IPM methods to target to increase IPM uptake in Wales ranked in order of priority, including barriers to adoption and methods to overcome barriers to adoption in the grassland sector IPM method ranked in order of priority (1= highest) 1) Removing disease inoculum Barriers to adoption Lack of independent information available regarding precise timings of inoculum removal to take place and lack of quantification of the effectiveness of removing disease inoculum on reducing disease levels. Methods to overcome barriers Further research into the effects of removing disease inoculum either by topping or by grazing intensively with sheep before winter. Low Priority Encouraging uptake in the amenity sector. The amenity sector is already moving more towards non-chemical control of weeds driven by limited availability of pesticides and sector pressures. v

7 Table ES 4 IPM methods to target to increase IPM uptake in Wales ranked in order of priority, including barriers to adoption and methods to overcome barriers to adoption in the amenity sector Ranking in order of priority Barriers to adoption Methods to overcome barriers 1) Optical/infrared targeting of pesticide applications Lack of independent information showing method efficacy, limited sources of equipment and poor efficacy of equipment on all surfaces. Research to trial use of optical/infrared targeting of pesticide applications in an amenity sector. Clear communication of results to amenity sector stakeholders. How could IPM adoption be increased? Adoption of IPM methods can be driven through necessity (reduced availability of pesticides), economics (costs of pesticides is higher than alternatives) and market requirements, but sufficient supporting information and advice is key to IPM method adoption. Further work in terms of education and guidance is required to increase adoption of some methods such as mechanical weeding, cover crops and pest thresholds in arable crops, and a range of others. Monitoring uptake: In order to assess the adoption of IPM methods there needs to be a robust methodology to measure uptake of IPM methods in Wales. This could be direct measurement through surveys of pesticide users and advisers, which could help to understand sector specific issues and barriers, however there is a significant cost associated with this. An alternative would be to identify key indicators such as usage of pesticides through FERA Pesticide Usage Surveys, sales of pesticides through annual trade reports and monitoring uptake of IPM training in Wales. Validation of estimated adoption levels: This project has not undertaken a comprehensive survey of IPM method adoption levels. Categorisation of adoption levels of IPM methods in Wales has been based on indicators such as, availability of evidence and advice and ADAS expert opinion. Further work is necessary to validate estimated adoption levels in Wales. vi

8 Contents Executive Summary... i 1. Introduction Objectives Methodology... 3 Overview... 3 Task 1: Current IPM methods... 3 Task 2: Assessment of IPM methods... 4 Task 3: Categorisation of methods... 5 Task 4: Recommendations for policy development Current IPM methods IPM method assessment IPM methods for weed control IPM methods to reduce pests IPM methods to reduce disease IPM methods for plant growth regulation Amenity weed control Categorisation of methods Methods with good supporting evidence, which are widely adopted Methods that have good supporting information, but are not yet widely adopted Methods that do not have good supporting information and are not widely adopted Integrating IPM methods within agriculture, horticulture and amenity sectors Recommendations Current status of IPM adoption IPM method sector priorities Encouraging uptake of IPM methods Monitoring progress Appendix 1 Pest thresholds Appendix 2 Evaluation of IPM methods Appendix 3 References... 72

9 1. Introduction Under the Sustainable Use Directive, Member States are required to promote Integrated Pest Management (IPM) in order to reduce pesticide use. In February 2013 a National Action Plan for the Sustainable Use of Pesticides was published by Defra covering the whole of the UK. Part of the remit of the plan includes information on how the UK proposes to ensure that all professional pest management is conducted under the principles of Integrated Pest Management (IPM), including training requirements, actions to increase the development and approval of biopesticides, incentives for uptake, and research and development activities. Integrated Pest Management is the careful consideration of all available plant protection methods and subsequent integration of appropriate methods that discourage the development of populations of harmful organisms and keep the use of plant protection products and other forms of intervention to levels that are economically and ecologically justified and reduce or minimise risks to human health and the environment 2. IPM is not a single pest control method, but a series of pest management evaluations, decisions and controls. Uptake of IPM methods is encouraged through legislation, voluntary initiatives, market pressure and crop research. Generally there is a four tier approach taken 3 : 1. Set action thresholds - This is when a pest population reaches a certain level or environmental conditions are met (e.g. blight - Smith - period) that action should be taken to prevent economic loss. 2. Monitor and identify pests - Not all pests need control, accurate identification allows appropriate control measures to be taken. This removes the possibility that unnecessary or incorrect pesticide applications are avoided. 3. Prevention - As a first line of pest control aim to avoid situations where the pest may become a threat. 4. Control - When monitoring, identification and thresholds indicate action should be taken, e.g. if preventative methods are not effective or available, then control measures can be taken. Less risky methods should be selected first e.g. mechanical weeding, trapping. If these are not available or do not work targeted pesticide applications are used. Field applications of nonspecific pesticides are the last resort. A wide range of IPM strategies exist and are already practised by growers of different crops to varying degrees. Some of the techniques are weather dependent with some being more effective in dry weather, whilst others are more effective in wetter conditions, therefore uptake of different approaches will vary year on year depending on the climatic conditions present at specific points in the season. This report reviews various IPM methods that are used in crops grown in Wales, with a particular focus on those that can lead to a reduction in pesticide use. 1

10 2. Objectives The main objective for this project is to review the IPM methods available for use in Wales in order to inform policy development in relation to the implementation of the Sustainable Use Directive. Specific tasks are: 1. To identify current IPM methods for crops grown in Wales (or crops which may be grown in Wales) focusing on agriculture and horticulture, but with some coverage of the amenity sector; 2. Assess selected methods against a set of criteria to include current adoption, current supporting evidence, availability of supporting advice and ease of adoption; 3. Categorise the methods in order to help identify next action; 4. Identify options for the Welsh Government to inform policy development. 2

11 3. Methodology Overview This report is based on a desk exercise using existing evidence and information. All information is referenced using footnotes, with information collected from scientific and advisory reports, supported by expert opinion. The project focused on eight crop sectors: grassland, forage crops, cereals, break crops, root crops, vegetable crops, fruit, and amenity. Priority crops were identified for each of the eight crop sectors (Table 1). Given that there is a certain amount of overlap between control measures in the sectors the report is set out under the following main headings; weed control, pest control, disease control and growth regulation, with a section for each relevant crop under these main headings. Table 1 Crop group and priority crop groups considered Crop Sector Priority Crop Welsh crop area (ha) Grassland New leys Temporary grassland 140,000 Permanent pasture 1,000,000 Rough grazing 260,000 Forage crops Maize 10,000 Fodder beet & other stock 19,000 feed Cereals Wheat 15,000 Barley 20,000 Oats 5,000 Break crops Oilseed rape 5,000 Other break crops inc. Field 2,000 beans and linseed Root crops Potatoes 2,600 Vegetable crops Brassicas 400 (Total veg) Leeks Fruit Strawberries 700 (Total fruit) Apples Amenity Roads / transport Parklands Sports pitches Task 1: Current IPM methods Task 1 involved identifying the IPM methods targeting the major weed, pest, disease and growth regulation issues in each of the crop sectors. This process conducted by a range of crop, weed, pest and disease experts using published reports, farmer guidance and expert opinion. Each IPM method was given a rating for likely importance (high, moderate or low) in Wales depending on the crop area, the proportion affected by target species and the potential to give good level of control (Table 2). This gave an indication of the likely potential for reducing pesticide use. 3

12 Table 2 Rating system of likely importance of IPM methods for reducing pesticide usage in Wales for use in Task 1 Importance rating Qualifying features High Large crop area; High proportion affected by target species; Good levels of control. Moderate Large crop area with moderate area affected by target species; or: Small crop area with high levels of target species; plus Moderate to good levels of control. Low Small crop area; Low incidence of target species; Poor levels of control. The output from this task is a table of IPM methods for each of the key target groups (weeds, pests, diseases and growth regulation) for each of the crops identified in Table 1. Task 2: Assessment of IPM methods Using information gathered from Task 1, IPM methods with moderate to high ratings on importance in Wales were assessed for each crop group to identify the following: Current adoption levels; Drivers for adoption (e.g. Regulations, Farm Assurance, market requirements, current guidance and advisory programmes); Current supporting evidence (e.g. availability and quality of thresholds research); Availability of supporting advice (e.g. BASIS advisers, Farming Connect, other publications etc.); Ease of adoption (e.g. knowledge/skills, specialist equipment, costs etc.); Key gaps and uncertainties. The output from this analysis is presented in five tables covering weed, pest and disease control, reduced PGR use and the amenity sector by crop group with more detailed commentary on the main methods. Many of the IPM methods to control weeds could be used on all of the crop groups and this is highlighted in Table 15 in Appendix 2. 4

13 Task 3: Categorisation of methods Task 3 involved using the information gathered during Task 2 to categorise each IPM method by crop group to help identify the next actions for policy development. A visual colour coding system was used. The categories used in the project are as follows: Methods with good supporting evidence and guidance, which are widely adopted; Methods that have good supporting evidence and guidance, but are not yet widely adopted; Methods that do not have good supporting evidence and guidance and are not widely adopted. The main sources of information for the study was from the Agricultural and Horticultural Development Board (AHDB) publications and websites (mainly HGCA, AHDB and HDC). Other sources of information included peer reviewed scientific literature and relevant books. Expert opinion was used to help categorise the importance of each IPM method in Wales and ease of adoption. Task 4: Recommendations for policy development The information and analysis was used to answer the following questions: What is current status of IPM adoption? What are the priorities for IPM in Wales? What could be done to encourage further uptake? How can it be monitored? 5

14 4. Current IPM methods The IPM methods available for use in the main Welsh crops are detailed in Tables 3-6. The tables are organised by weed, pest and disease control and reduced growth regulation rather than by crop to avoid unnecessary repetition as many methods are common to multiple crops. The results summarise the methods available. More details on each of the methods is contained in following sections of the report Table 3 Weed Control - List of relevant IPM methods for agriculture, horticulture and amenity in Wales Crop Group Priority Crop IPM methods available Potential importance of IPM method in Wales Grassland Temporary Mowing Moderate grassland Forage crops Maize Include a cover crop Low Fodder beet & other stock feed Mechanical weeding Leave low levels of weeds Include a cover crop Mechanical weeding Leave low levels of weeds Low Low Low Low Low Sow in the spring Moderate Cereals Wheat Competitive varieties Low Stale seed bed High Alter drilling date Moderate Increase seedrate Moderate Mechanical weeding Low Leave low levels of weeds Low Rotational ploughing High Barley Sow in the spring Moderate Stale seed bed High Include a cover crop Low Increase seedrate Moderate Mechanical weeding Low Leave low levels of weeds Low Rotational ploughing High Oats Sow in the spring Moderate Stale seed bed High Include a cover crop Low Increase seedrate Moderate Mechanical weeding Low Leave low levels of weeds Low Rotational ploughing High Break crops Oilseed rape Sow in the spring Moderate Include a cover crop Low Mechanical weeding Low Targeted herbicide use Rotational ploughing Sow in the spring Low Low Moderate 6

15 Crop Group Priority Crop IPM methods available Potential importance of IPM method in Wales Include a cover crop Leave low levels of weeds Rotational ploughing Low Low High Root crops Potatoes Include a cover crop Low Alter planting date Re-ridging Leave low levels of weeds Moderate Moderate Low Vegetable crops Brassicas Include a cover crop Low Mechanical weeding Rotational ploughing Leeks Include a cover crop Low Mechanical weeding Leave low levels of weeds Fruit Strawberries Sow in the spring Moderate Amenity Include a cover crop Competitive varieties Alter drilling date Mechanical weeding Leave low levels of weeds Rotational ploughing Moderate- crop grown in rows allowing application of mechanical weeding. GPS technology aiding adoption of mechanical weeding. High Moderate- crop grown in rows allowing application of mechanical weeding. GPS technology aiding adoption of mechanical weeding. Low Low Low Moderate Low Low High Apples Include a cover crop High Mowing Leave low levels of weeds Roads / transport Sweeping/mechanical cleaning Parklands Hand weeding Thermal destruction Optical/infrared targeting of pesticide application Mowing or cutting Weed suppression/mulching Hand weeding Low Low High High Low High High High 7

16 Crop Group Priority Crop IPM methods available Potential importance of IPM method in Wales Mowing High Sports pitches Mowing High Variety selection Biologicals Moderate Low Table 4 Pest Control - List of relevant IPM methods for agriculture, horticulture and amenity in Wales Crop Group Priority Crop IPM methods available Potential importance in Wales Grassland Temporary grassland Cultivations, particularly rotary Delayed sowing Fertiliser application Rolling High Moderate Moderate Moderate Forage crops Maize Early sowing High Cultivations, particularly rotary Moderate Rolling to consolidate seed bed and aid establishment High Cereals Wheat Pest thresholds High Delayed sowing Rolling to consolidate the soil, fertiliser application Variety choice Early ploughing after grass ley (four weeks pre-drilling) Early sowing of spring crops Low High High Moderate Moderate Barley Pest thresholds High Delayed sowing Rolling to consolidate the soil, fertiliser application Variety choice Early ploughing after grass ley (four weeks pre-drilling) Low High Low Moderate Oats Early sowing spring oats Moderate Delayed sowing Low 8

17 Crop Group Priority Crop IPM methods available Potential importance in Wales Rolling to consolidate the soil Fertiliser application Cultivations, particularly rotary High Moderate Moderate Break crops Oilseed rape Pest thresholds High Delayed sowing Low Other break crops inc field beans, linseed Early sowing of spring rape Rotate crop around farm Preparation of good seedbed to encourage rapid establishment Moderate Low High Root crops Potatoes Pest thresholds High Variety choice Low Lift potatoes early Moderate Vegetable crops Brassicas Monitoring High Physical barriers High Site selection and crop rotation Diverse crop margins Removing crop debris/weeds High Low High Leeks Monitoring High Physical barriers Site selection and crop rotation Diverse crop margins Removing crop debris/weeds High High Low High Fruit Strawberries and apples Monitoring High Hygiene High Resistant varieties Moderate 9

18 Crop Group Priority Crop IPM methods available Potential importance in Wales Exploiting natural beneficial organisms Biological control Moderate Moderate Table 5 Disease control - List of relevant IPM methods for disease control for agriculture, horticulture and amenity in Wales Crop Group Priority Crop IPM methods available Potential importance in Wales Grassland Temporary grassland Variety disease resistance Moderate Removing disease inoculum Low this may change as cropping area of this crop increases Forage Maize Variety disease resistance Low crops Cultivations to reduce High fusarium Fodder beet & other stock feed Variety disease resistance High most varieties are disease tolerant Cereals Wheat, barley and oats Optimal nutrition High but not necessarily for disease control Threshold Models Low for foliar diseases as they are hard to predict. More important for stem based diseases Variety Medium Yield is the most important factor Risk assessment for mycotoxin reduction High requirement of grain marketing Break crops Root crops Potatoes Vegetable crops Rotation High Oilseed rape Disease thresholds High for diseases such as Phoma Live monitoring and Low/ Moderate, but guidance expanding. Often used Brassicas Leeks Optimising nutrition Variety Weather guidance (smith periods) Irrigation (for scab control) Store conditioning Hygiene Biological Control Rotation by agronomists. High but not necessarily for disease control Moderate Yield is the most important factor High for the control of potato blight Moderate high cost Moderate High, depending on level of store investment Moderate often these techniques lapse at peak times Low efficacy can be variable Moderate 10

19 Crop Group Fruit Priority Crop IPM methods available Potential importance in Wales Variety resistance Moderate depends on crop. Quality is the number one factor Storage High Strawberries Storage High Apples Cultural control High Forecasting Moderate Table 6 Growth regulation - List of relevant IPM methods for agriculture in Wales Crop Group Priority Crop IPM methods available Potential importance in Wales Cereals Wheat, barley, oats Deep sowing Direct drilling Delayed sowing Variety choice Optimising nutrition Break crops Oilseed rape Decrease plant density Variety choice Low Low 11

20 5. IPM method assessment Priority methods for each pest group and crop were selected from the full list based on the rating of importance to reducing pesticide usage in Wales. The selected IPM methods were reviewed in more detail to assess the following: Current level of adoption; Drivers for adoption; Availability and quality of supporting evidence; Key gaps and uncertainties. Details of the most important methods for Wales are provided in the following section, providing evidence of the efficacy of the methods, organised by weed control, disease control, pest control and growth regulation as many are applicable to multiple crops, and a separate section on amenity weed control. The full analysis of results is provided in Appendix 2- Evaluation of IPM methods. IPM methods for weed control Crop Rotation Applicable to all rotational crops especially cereals and break crops Use of varied crop rotation as a weed control method is widely adopted throughout Wales, mainly due herbicide resistance, as well as being part of good agronomy practice. Varied crop rotations are a fundamental aspect of good weed management systems and if used correctly can reduce weed burden and associated pesticide use. The choice of crop affects the type and timing of cultivations and time of drilling. In spring crops there is selection for spring germinating weeds 4 and likewise selection for autumn germinating weeds in autumn sown crops. The weed seed bank may contain similar numbers and species of weeds, but the frequency of their occurrence as growing plants varies with respect to the crop sown at the time 5. Introducing grass leys into a crop rotation can lead to reductions in populations of black-grass (not a significant problem in Wales) and wild-oats, but build up populations of couch grasses and perennial weeds 6. Disrupting these crop/weed associations is a basic approach to actively discouraging the growth and reproduction of certain weed species. Despite the importance of crop rotation for weed control there has been limited work done on rotations due to their complexity. In Scandinavia 7 experiments failed to detect a significant effect of rotation on the weed flora or only a slightly detectable one 8. In Canada 9, it was reported that rotation only accounted for 5.5% of the variation in weed flora, whilst weed management accounted for 37.9%. Similarly in France 10 11, it was reported that species density was regulated to a greater extent by weed management factors, but the difference between the actual flora and the seedbank was influenced more by crop rotation. The introduction of cover crops into the rotation can also aid weed control and reduce pesticide use by competing with and suppressing weeds from germinating 12. Cover crops are sown before or after a crop to minimise the time the soil is left without green cover. Cover crops can suppress weeds through multiple ways during the lifecycle of an annual weed. Different phases of the lifecycle will be affected by different mechanisms depending whether the cover crop is acting during the living phase or as post-mortem residue. 12

21 Live cover crops will reduce the amount of light penetrating to the soil surface to prevent seed germination 13. The level of suppression from the cover crop depends on the species; rye (Secale cereale), hairy vetch (Vicia villosa) and clovers (Trifolium spp) are more effective as cover crops in the autumn and winter than in the summer. In the Netherlands research has shown that fodder radish, winter oilseed rape and winter rye were the most competitive species 14. After cover crops have been killed off, the residues can prevent weeds from establishing, but this is not as successful as the suppression provides by live crops. Residues through their bulk can impede the emergence of seedlings and prevent light from reaching them 15. Residues can also lower the soil temperature (by preventing the sun warming the soil), prevent temperature fluctuation and reduce the light intensity at the soil surface 16 preventing germination of the weed seed. Introducing a varied crop rotation into the farming system is relatively straightforward and can provide additional benefits to weed control and reduce pesticide use such as increasing soil organic matter, nitrogen fixation and protecting from soil erosion and sediment run-off into watercourses Ploughing Applicable to all arable crops Primary cultivation is the first cultivation that is conducted to prepare the soil for the next crop and can be classified into four groups; plough, deep and shallow till, no-till and others. Changing the primary cultivation is an effective method in changing weed populations, which can affect pesticide usage. Ploughing inverts the soil, burying 95% of freshly shed seed to 15-20cm but brings up 35% of old seed buried by previous cultivations (Table 7). Subsequent shallow cultivations to establish the crop generally do not to disturb the buried seed. Most of the seed that germinates is seed shed in previous seasons. Generally, ploughing reduces weed populations, particularly grass weeds, which can reduce the need for herbicide applications. Research has also shown that annual meadow grass (Poa annua) seed numbers were 70% lower after 9 years of ploughing compared to shallow rotary tillage 17 and ploughing can also help to keep perennial weeds at manageable levels in annual crops. The use of ploughing as a weed control method is widely adopted, particularly in those areas with a high black-grass burden (more of a problem in parts of England than Wales). Ploughing is seen by many growers as a standard agricultural practice, and so adoption is straightforward as most farms own a plough or can access one through contractors. Supporting evidence comes from both scientific literature and HGCA guidance which is promoted by crop advisors and agronomists. 13

22 Table 7 Cultivation options and effects on the weed seed bank Stale seed beds Applicable to all cereal and break crops A stale seed bed is used for weed control by creating a seed bed before the crop is due to be sown. The soil should be consolidated in advance of the planned sowing date to allow enough time for the weeds to germinate and be controlled by a non-selective herbicide prior to drilling 18. Depending on the date of sowing, several flushes of weeds can germinate and subsequently be sprayed off, or cultivated in before the crop is drilled. The stale seedbed technique is useful for barren brome, black-grass and volunteer control, but not for other brome species. Timing is important to the success of stale seedbeds for weed control as the weed seeds must be controlled before they re-seed in the autumn/winter or spring. Adoption of the method is straightforward, if stale seedbeds are planned in advance. UK farmers are increasingly considering this option for weed control. However, there are risks associated with using stale seed bed techniques, especially for the establishment of winter crops. In wet years there is the risk that delays to drilling will result in poor crop establishment and poor winter survival rates, or even a complete failure to access land to drill in the first place. In dry conditions there is the risk that the soil disturbance will allow vital moisture to evaporate more easily drying out the seed bed further, and a lack of moisture will inhibit weed emergence, reducing the effectiveness of the stale seed bed. Evidence supporting stale seed beds as a technique comes from scientific literature, AHDB-HGCA publications and agronomist advice Seed rates Applicable to all arable crops Increasing seed rate in crops can suppress weeds by making the crop more competitive over the weeds, reducing the need for pesticide use. Increasing winter wheat populations to over 100 plants/m² reduced the number of black-grass heads by 15% for every increase in 100 plants up to 350 plants/m². The use of seed rates for weed control is widely adopted as it is easy and can be cost effective to increase seed rate in cereals, but there are limitations in field vegetables as crops need to be grown at specified spacings to achieve marketable produce to specific size grades. Supporting evidence predominantly comes from scientific literature and this is supported by advice from agronomists and crop 14

23 advisors. Note high seed rates can increase risk of lodging, and therefore PGR requirements Mechanical weeding Row crops Vegetables, fruit and some arable crops Mechanical weeding can be used to control weeds growing between or within crop rows using a wide range of hoe shapes. Mechanical weeding methods are based on killing weeds by burying, cutting or uprooting them. The efficacy of the weeding operation depends upon a wide range of factors including environmental conditions, weed species and size and the skill of the operator. Weeders can be powered by the tractor or ground driven and either front or rear mounted. Front mounted versions can be steered by the tractor driver, by a computerised vision guidance system, or by GPS technology. Rear mounted systems may have an extra operator positioned on the implement or again use an electronic vision guidance system. In the more sophisticated systems a combination of weeder types can be used with an inter-row hoe breaking up the soil between the rows and an intra-row hoe removing the weeds within the row. The choice of implement, and the timing and frequency of its use may depend on the crop and on the weed population. Some implements, such as fixed harrows, are thought more suitable for arable crops, while others like inter-row brush weeders are considered to be more effective for horticultural use. Adoption is straightforward as it involves the purchase of a hoe and having a machine with the correct horse power (hp) to pull the hoe, therefore there is a potential economic barrier especially in lower value commodity crops. There is evidence to support the efficacy of mechanical weeding from both scientific literature and AHDB-HGCA guidance, which can aid adoption in Wales. However, often with mechanical weeders there is a negative effect on the crop and this must be balanced against the positive effects of removing the weeds. The size of the impact on yield depends on crop type and technique used as well as a host of other factors, including operator skill Spring cropping Spring cropping has declined since the 1970s, the change was part economically driven, aided by support from the CAP and part by improvements in technology through improved mechanisation and pesticides allowing for more effective establishment of higher yielding winter crops. The change from spring cropping to predominantly winter cropping has altered the weed spectrum in most arable fields. Most spring crops are associated with improved biodiversity compared to winter crops, as the presence of an uncropped stubble over the autumn and winter period allows weed seeds to germinate or be eaten by birds. The use of overwintered stubbles and spring cropping is promoted under Environmental Stewardship. There is little current research into spring cropping and its effects on weed population (outside of sugar beet and potatoes), although supporting evidence can be found through BASIS advisers, HGCA publications 19. This method is easy to adopt as spring cropping provides a good opportunity to reduce grass weed populations through cultivations or pesticides, but the incidence of spring germinating weeds is likely to increase and spring cropping yields are often lower than winter crops. 15

24 IPM methods to reduce pests Thresholds Applicable to all arable crop types Thresholds are a valuable method of determining whether or not control measures (e.g. pesticides) are necessary against a particular pest. Pest thresholds are generally defined in terms of a number of the pest per unit area or per plant or part of plant above which there is likely to be an economic loss of yield. This would then mean that the economic value of the potential yield loss would be greater than the cost of employing the control measure. Sensible use of pest thresholds allows farmers and agronomists to ensure that pesticides are applied only when absolutely necessary. Robust, empirically-derived pest thresholds allow the most economic use of crop inputs and avoid unjustified prophylactic use of pesticides thus limiting adverse environmental impact and minimising the risk of resistance development. For thresholds to be effective, farmers and agronomists need to be confident that they accurately reflect the risk of economic loss in relation to current crop varieties, contemporary agronomic practices, and input and output prices. Lack of confidence can lead to the use of insurance sprays, which may be environmentally damaging, increase the risk of resistance development and decrease gross margins. However, thresholds are not universally used to help determine the need for pesticide treatment. For example, a recent AHDB HGCA review of farmers and agronomists showed that only 23% used pest thresholds for % of their pest management decisions 20. There are a number of possible reasons why thresholds are not used more widely. Firstly, many thresholds were developed over twenty years ago and so may no longer be applicable to current crop varieties or farming practices. Secondly, some thresholds are based on anecdotal evidence and so are considered of doubtful provenance when compared with those derived from robust scientific investigation. Thirdly, the low cost of some frequently-used insecticides (e.g. synthetic pyrethroids) has led to an increased tendency to apply insurance treatments. This situation is clearly not sustainable. The range of available active ingredients may decline in future, as a result of regulations such as the implementation of the new approvals legislation EU 1107/2009 and the Water Framework Directive. This may, in turn, increase the risk of insecticide resistance if existing products are used too frequently or unnecessarily. It will become increasingly important to safeguard existing products and ensure that they are used only when absolutely necessary. This means confidence in, and understanding of, pest thresholds must be improved. Furthermore, recent research into the physiology of crops has revealed that they have a wide range of tolerance to damage inflicted by pests as a result of different crop management and environmental conditions impacting on crop growth. This has the potential to reduce pesticide inputs, but is not taken into account in current thresholds. Although there are reservations about existing thresholds they represent the state of current knowledge and should be used wherever possible to reduce reliance on insurance treatment of pesticides. Appendix 1 Pest thresholds provides a list of currently available thresholds for a range of arable crops. Populations of some pests can build up under long-term leys. The need for pesticide use can be avoided if crops that follow the ley are not vulnerable to the pests that maintain themselves in the ley. For example: wireworms, Agriotes spp., develop in grassland and populations can persist for several years after ploughing up the ley. Vulnerable crops such as potatoes should not be grown after leys until the risk of damage has diminished, which can take five years. 16

25 Some pests are relatively immobile and increase in numbers only when their host crop is grown too frequently in the same field. Examples include orange wheat blossom midge (OWBM) - Sitodiplosis mosellana, saddle gall midge - Haplodiplosis marginata, and potato cyst nematode (PCN) - Globodera spp. Growing alternative, non-host crops for appropriate periods can avoid the build-up of these pests whilst remaining economically viable 21. The time period needed to grow break crops depends on the pest, e.g. one or two years is enough for saddle gall midge populations to decline to low levels whereas up to eight years is needed for PCN numbers to decline, depending on the population density in the field Pest Monitoring and thresholds Applicable to arable and horticultural crops fruit and vegetables Pest monitoring is the foundation to any pest management programme and can reduce pesticide use by only spraying when pests reach a certain threshold (see section 5.2.1). Monitoring can include a variety of methods. The most effective is walking the crop and inspecting plants for pests and their damage. At low pest densities, pests may not always be detected by walking through the crop, which is when monitoring traps can be used to provide advanced warning. Traps should be used in addition to crop walking and checked weekly. Traps can be simple sticky traps or combined with a pheromone lures, which are attractive to specific pests. Pheromone lures and sticky traps can be used to capture orange wheat blossom midge (OWBM). Winter wheat crops are susceptible to OWBM from ear ¼ emerged (GS 53) to ear fully emerged (GS 59). The risk to a crop depends on the proportion of ears at this critical stage when midges fly. Unless resistant varieties are grown crops must be monitored and, if necessary, sprayed. Pheromone traps attract male midges and so provide the earliest warning of midge activity. The traps are placed within fields that have been affected by OWBM in the past two years, whether the current crop is cereals or not. A minimum of two traps should be placed in each field and the traps attached at crop height to stakes when the flag leaf is swollen (GS 45). The traps should be left in position until any crop in the immediate area has reached flowering (GS 61). Pheromone traps should be placed to cover discrete blocks of cereals, with each block representing different soil types, rotation, rainfall or soil temperature across the farm. The thresholds for treatment based on pheromone catches is shown in Table 8. Table 8 Pheromone trap catches (midges/trap/day) compared to owbm risk to crops 22 Pheromone trap catches (midges/per trap/per day) 30 or more General risk to crops in following week when fertilised females lay eggs. Crops should be monitored for female midges. Over 120 Very high risk. Wheat crops should be treated in surrounding fields at susceptible growth stage as soon as possible. 17