Publication - Statistics

Pesticide usage: outdoor vegetable crops 2019

Information from a survey of pesticide use on outdoor vegetable crops grown in Scotland during 2019.

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Contents
Pesticide usage: outdoor vegetable crops 2019
Appendix 6 – Integrated pest management

88 page PDF

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Appendix 6 – Integrated pest management

It is a requirement of the EU Sustainable use of Pesticides Directive (2009/128/EC)(14) that member states should promote low pesticide input pest management, in particular Integrated Pest Management (IPM).

The Directive defines IPM as follows "'integrated pest management' means careful consideration of all available plant protection methods and subsequent integration of appropriate measures 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.  'Integrated pest management' emphasises the growth of a healthy crop with the least possible disruption to agro-ecosystems and encourages natural pest control mechanisms."

Information about the uptake of IPM measures by Scottish growers was collected alongside the 2019 outdoor vegetable crops pesticide usage survey. IPM data have previously been collected and published for all crop groups in our cycle of pesticide usage surveys (vegetable crops 2015(4), protected edible crops 2015(16), arable crops 2016(17), soft fruit crops 2016(18) and fodder crops 2017(19)). Following collection of this baseline data, our intention is to monitor IPM uptake in each crop sector every four years.  This 2019 IPM survey represents the second in the series of surveys of IPM measures on vegetable crops, allowing the adoption of IPM techniques to be monitored. These datasets will be used as an indicator of the success of Scottish Government funded IPM research, knowledge transfer and promotion activities.

Unlike the other statistics in this report, the figures reported in this section are not raised to produce national estimates, but represent only the responses of those surveyed.  The IPM sample, whilst smaller than that sampled for the pesticide usage survey, provides a good representation of Scottish regions and farm size groups.  When comparing between 2015 and 2019, any noticeable differences are recorded in the text.  If no comparison is made then the responses recorded are similar between 2015 and 2019.

In total IPM data was collected from 27 growers and grower groups representing 63 holdings and collectively growing 1,477 ha of crops.  This sample represented eight per cent of Scotland's 2019 outdoor vegetable crop area.  Of these growers, 67 per cent had an IPM plan (33 per cent completed their own IPM plan and 33 per cent had a plan completed by their agronomist) and 33 per cent did not have an IPM plan (Figure 26).  This represents a significant increase (P<0.05) in the use of IPM plans from the 2015 survey where 36 per cent of growers had an IPM plan.  Using an IPM plan helps growers to make the best possible, and most sustainable, use of all available methods for pest control.  Since the 2015 survey, the requirement to complete an IPM plan has been added to some farm assurance schemes; for example, farmers certified with Red Tractor are required to complete the NFU/VI IPM plan(20).  Farmers certified with Scottish Quality Crops (SQC) must complete an IPM plan, a biodiversity plan and a soil testing plan(21).

Figure 26 IPM: Percentage of respondents with an IPM plan 2015-2019
Figure 26: Bar chart of percentage responses to questions about IPM plans where more respondents have IPM plans in 2019.

Note: The increase in respondents with an IPM plan is statistically significant (P<0.05)

Although more plans were completed in 2019, there was no change in the proportions of plans completed by growers and by agronomists, with around 50 per cent of IPM plans completed by growers and 50 per cent completed by agronomists in both years.  Of those growers who had an IPM plan in 2019, either completed themselves or by their agronomist, 37 per cent used the Scottish Government IPM plan, 21 per cent used the NFU/VI plan, 21 per cent used the LEAF plan and 21 per cent used their own plan (Figure 27).  

Figure 27 IPM: Type of IPM plan - 2019
Figure 27: Pie chart of plan types in 2019 where the Scottish Government plan is the most common.

Farmers were asked about their IPM activities in relation to three categories; risk management, pest monitoring and pest control.  Information was collected about all activities each grower conducted in relation to these categories and the responses are reported in the following sections.  The term 'pest' is used throughout to denote diseases, weeds and invertebrate pests.

Risk management

IPM programmes aim to prevent, or reduce, the risk of pests becoming a threat by minimising the likelihood of damage occurring that will require subsequent control.  Table 32 presents an overview of the risk management measures adopted by those growers surveyed.  In both 2019 and 2015, all growers sampled reported that they implemented at least one measure associated with an IPM risk management approach.  There were no statistically significant differences in the responses to summary risk management questions between 2015 and 2019.

Table 32 IPM: Summary of responses to risk management questions 2015-2019
Risk management activity Percentage positive response
2019 2015
Crop rotation 96 96
Soil testing 96 88
Cultivation of seed bed 81 76
Cultivations at sowing  56 52
Varietal or seed choice  89 88
Catch and cover cropping 44 36
Protection or enhancement of beneficial organism populations 81 72
Any risk management activity 100 100

Ninety six per cent of growers in both 2019 and 2015 used crop rotation to reduce the risk of pest damage.  Rotation breaks the link between pathogen and host, reducing pest population build-up.  It can also improve soil fertility and structure, and consequently crop vigour. 

The majority of growers (96 per cent) tested their soil in order to tailor inputs to improve crop performance, this was an increase from 88 per cent in 2015 (Table 32).  Soil testing allows growers to make informed decisions about the inputs required and optimal crop choice for their land.  Most testing encountered in 2019 was for pH or lime (89 per cent).  This was the biggest change observed from 2015, however, growers were not asked directly about testing soil for pH or insects in 2015, therefore these responses are underestimated in 2015 (Figure 28).  There were some decreases from 2015 in the proportions of growers testing for nutrients (84 per cent to 74 per cent), soil borne disease such as clubroot (60 per cent to 41 per cent) and nematodes (44 per cent to 30 per cent).  In 2019, lower proportions of growers tested for insects (seven per cent), conducted soil health tests (seven per cent), organic matter assessments and electrical conductivity tests (four per cent each).

Figure 28 IPM: Soil testing 2015-2019
Figure 28: Bar chart of percentage responses to questions about soil testing where pH and lime testing is most common in 2019.

Note: In 2015 growers were not directly asked about testing for insects, pH or lime. However, pH testing was recorded under other in 2015. Therefore the 2015 data are underestimated
'Other' in 2019 included soil health tests, organic matter assessments and electrical conductivity tests.
'Other' in 2015 included texture and electrical conductivity tests.

The majority of growers in 2019 (81 per cent) and in 2015 (76 per cent) reported that they managed their seed bed agronomy to improve crop performance and reduce pest risk (Table 32).  In 2019, 59 per cent of growers increased soil organic matter and 52 per cent used a stale seedbed for weed management (Figure 29).  A similar pattern was observed in 2015.  Stale seed beds allow weeds to germinate before sowing the next crop; these are treated with a herbicide, depleting the seed bank, and resulting in lower weed pressure, and potentially pesticide use in the succeeding crop.  Thirty per cent of growers considered pest management when planning irrigation and drainage, an increase from eight per cent in 2015.  Other methods employed by growers in 2019 included 19 per cent using non-inversion techniques such as min till and direct drilling and seven per cent using rotational ploughing.  These techniques can preserve organic matter in the soil.  In 2015, other techniques included deep ploughing used by four per cent of respondents.

In 2019, 56 per cent of growers amended cultivation methods at sowing with the aim of increasing crop success, a similar proportion to 2015 (Table 32).  Thirty per cent varied the date of sowing, 22 per cent varied the sowing rate or density, 15 per cent used pest free growing media such as pre-treated modules (an increase from eight per cent in 2015).  Four per cent varied the sowing depth and four per cent used different spatial cultivation arrangements to allow for more effective weeding (Figure 30).

Figure 29 IPM: Seed bed cultivations 2015-2019
Figure 29: Bar chart of percentage responses to questions about seed bed cultivations where all categories have increased from 2015.

Note: 'Other' in 2019 included min till, direct drilling, rotational ploughing, considering pest management when planning crop nutrition
'Other' in 2015 included deep ploughing

Figure 30 IPM: Cultivations at sowing 2015-2019
Figure 30: Bar chart of percentage responses to questions about cultivations at sowing where varying sowing date is most common method.

Note: 'Other' in 2019 included using different spatial arrangements to facilitate more effective weeding

The majority of growers in 2019 and 2015 considered risk management when selecting seeds and/or varieties (Table 32).  In 2019 there were increases in the proportions of growers using seed treatments, certified seed and variety diversification when compared to 2015 (Figure 31).  Fifty six per cent of growers used seed treatments, both pesticide seed treatments to protect seedlings at crop emergence and growth promotors to improve crop establishment.  Fifty six per cent selected pest resistant varieties to reduce damage and the need for pesticide input, 52 per cent used certified seed and seven per cent tested home saved seed.  Thirty seven per cent of growers used diversification of varieties to increase overall crop resilience to pests and environmental stresses.

Figure 31 IPM: Variety and seed choice 2015-2019
Figure 31: Bar chart of percentage responses to questions about variety and seed choice where most categories have increased from 2015.

Forty four per cent of growers sowed catch or cover crops in 2019, a small increase from 36 per cent in 2015 (Table 32).  In 2019 there were increases in the proportions of growers using cover crops to improve soil quality, for weed control, to attract natural predators and to manage soil pests by biofumigation (Figure 32).  Thirty seven per cent of growers used cover and catch crops such as clover and phacelia to improve soil quality.  Eleven per cent were used to suppress weeds, 11 per cent used crops such as marigold and borage to attract natural predators, seven per cent used crops such as mustard or radish with bio-fumigation properties and seven per cent used crops to manage soil pests directly.  Four per cent of cover crops were used to prevent soil erosion.

Figure 32 IPM: Catch and cover cropping 2015-2019
Figure 32: Bar chart of percentage responses to questions about catch and cover cropping where improving soil quality is most common reason

Finally, 81 per cent of growers stated that they adopted techniques to protect or enhance populations of beneficial organisms, an increase from 72 per cent in 2015 (Table 32).  In 2019 there were increases in the use of uncultivated areas and habitat mosaics and a decrease in the use of wildflower strips (Figure 33).  Seventy per cent left uncultivated areas, including leaving margins, headlands, endrigs and other areas wild and using buffer strips to increase biodiversity.  Thirty seven per cent maintained a habitat mosaic including planting and maintaining hedgerows, tree planting and pond creation.  Nineteen per cent planted pollen sources and 15 per cent planted wildflower strips.  Fifteen per cent took part in an agri-environment scheme, with the main scheme reported as the Scottish Government agri-environment climate scheme (AECS). A number of additional actions to support beneficial organism populations were also reported.  These additional measures included establishing beetle banks, planting wild bird seed and leaving wood piles (each seven per cent).  Other minor categories included selecting pesticides to reduce their effects on beneficial organisms, planting species rich grassland and margin mixtures (each four per cent).

In 2019, 11 per cent of respondents reported that as they were using rented ground and therefore were unable to either use catch or cover crops or implement features for beneficial organisms in the areas where they were growing vegetable crops.

Figure 33 IPM: Protection and enhancement of beneficial organism populations 2015-2019
Figure 33: Bar chart of percentage responses to questions about protecting beneficial organisms where using uncultivated areas is most common method.

Note: 'Other' in 2019 included planting wild bird seed, leaving wood piles selecting pesticides to reduce their effects on beneficial organisms, planting species rich grassland and margin mixtures

Pest monitoring

In IPM, pests are monitored both to determine whether control is economically justified and to effectively target control options.  IPM programmes aim to monitor and identify pests, so that appropriate control decisions can be made in conjunction with action thresholds.  Table 33 presents an overview of the pest monitoring measures adopted by the growers surveyed in 2015 and 2019.  The responses show little change between 2015 and 2019.  There were no statistically significant differences in the responses to summary pest monitoring questions between 2015 and 2019.  In both years, the majority of growers sampled (96 per cent) reported they implemented at least one pest monitoring measure.

Table 33 IPM: Summary of responses to pest monitoring questions 2015-2019
Pest monitoring activity Percentage positive response
  2019 2015
Monitor and identify pests 96 96
Regular monitoring of crop growth stage 96 96
Setting action thresholds for crops 89 88
Use of specialist diagnostics 59 60
Any pest monitoring activity 96 96

Ninety six per cent of growers reported that they regularly monitored and identified pests and 96 per cent regularly monitored crop growth stages (Table 33).  Most growers (89 per cent) also used action thresholds when monitoring pest populations. Pest monitoring information was primarily gained by seeking advice from a BASIS qualified agronomist (85 per cent) (Figure 34).  There was an increase in the proportion of growers using self-inspection of crops to collect information from 28 per cent in 2015 to 67 per cent in 2019.  In 2019 there were increases in the use of risk warnings, technical bulletins and press articles (48, 44 and 22 per cent of growers respectively).  Trapping was used by 44 per cent of growers, a similar proportion to 2015.  Other methods of pest monitoring reported in 2019 included using weather data to estimate risk (19 per cent) and local information from other farmers and growers (four per cent).

Figure 34 IPM: Monitoring and identifying pests 2015-2019
Figure 34: Bar chart of percentage responses to questions about monitoring pests where most common method is using BASIS qualified agronomist.

Note: 'Other' in 2019 included weather data and local information from other farmers and growers

Fifty nine per cent of respondents also used specialist diagnostics when dealing with pests that were more problematic to identify or monitor (Table 33).  Forty four per cent of growers used field or pest mapping (predominately field mapping) to aid crop monitoring (Figure 35).  Forty one per cent used tissue testing for nutritional deficiencies, a decrease from 52 per cent in 2015.  Nineteen per cent of growers used clinic services to identify unknown pests, compared to 24 per cent in 2015.  In 2015, testing for chlorophyll levels was used by four per cent of respondents.

Figure 35 IPM: Use of specialist diagnostics 2015-2019
Figure 35: Bar chart of percentage responses to questions about specialist diagnostics where mapping and tissues testing are most used.

Note: 'Other' in 2015 included testing for chlorophyll levels

Pest control

If monitoring, identification, and action thresholds indicate that pest control is required, and preventive methods are no longer effective or available, IPM programs evaluate the best control method in relation to effectiveness and risk.  Control programmes incorporate non-chemical methods alongside, or instead of, chemical control.  Use of chemical pest control should be as targeted as possible and the risk of resistance development should be minimised.  The effectiveness of the control programme should be reviewed regularly to gauge success and improve their regime as necessary.  Table 34 presents an overview of the pest control measures adopted by the growers surveyed.  Of the holdings sampled in 2019, 19 per cent were organic, an increase from 12 per cent in 2015.  In 2019 there was an additional four per cent which was not organic but did not use pesticides this season.  This may have an impact on the responses to questions on use of pest control, in particular relating to targeting pesticide use, anti-resistance strategies and monitoring the success of crop protection measures.  Where holdings were registered as organic or not using pesticides, they would also not have implemented such crop protection measures.  Therefore, changes in these responses between the years may have been influenced by an increase in the proportion of holdings not using pesticides in 2019.

Ninety six per cent of the growers sampled in 2019 adopted at least one IPM pest control activity, a small decrease from 100 per cent in 2015.  There were no statistically significant differences in the responses to summary pest control questions between 2015 and 2019.

Table 34 Summary of responses to pest control questions 2015-2019
Pest control activity Percentage positive response
  2019 2015
Non-chemical control used in partnership or instead of chemical control 81 76
Targeted pesticide application 70 76
Follow anti-resistance strategies 74 80
Monitor success of crop protection measures 93 100
Any pest control activity 96 100

Eighty one per cent of growers reported that they used non-chemical control in partnership or instead of chemical control, a small increase from 76 per cent in 2015 (Table 34, Figure 36).  The most common non-chemical method employed in 2019 was mechanical weeding used by 44 per cent of respondents, an increase from 36 per cent in 2015.  A range of physical control methods which prevent pest access to the crop were also used.  Netting was used by 26 per cent of growers in 2019, a decrease from 48 per cent in 2015.  Mulches such as plastic and fleece were each used by 11 per cent of growers.  The use of biocontrol and biopesticides increased from eight per cent in 2015 to 15 per cent in 2019.  Trapping was used by four per cent of growers, a decrease from 12 per cent in 2015.  Other methods of non-chemical control used in 2019 were using plant elicitors to encourage natural defences and garlic to protect crops from carrot fly, each used by four per cent of growers.  Other non-chemical methods used in 2015 included using garlic to protect swede from flea beetle and using salt water and vinegar to control slugs (each used by four per cent of growers).

Figure 36 IPM: Non-chemical control 2015-2019
Figure 36: Bar chart of percentage responses to questions about non chemical control where mechanical weeding and netting are most used.

Note: 'Other' in 2019 included using plant elicitors to encourage natural defences and garlic to protect carrot crops from carrot fly. 

'Other' in 2015 included using garlic to protect swede from flea beetle and salt water and vinegar for slugs

Seventy per cent of growers in 2019 stated that they targeted their pesticide applications to reduce pesticide use, a decrease from 76 per cent in 2015 (Table 34).  The most common method used by 52 per cent of growers in 2019, was reducing their dosage or frequency of pesticide applications, an increase from 40 per cent in 2015 (Figure 37).  Forty four per cent of growers decreased pesticide application by using drift reduction apparatus, an increase from 20 per cent in 2015.  Precision applications such as inter-row herbicide treatments as seen on carrots were used by 33 per cent of growers, similar to the proportion recorded in 2015.  Spot treatments (applying only to the affected area) were used by 26 per cent of growers in 2019, compared to 20 per cent in 2015.  The use of weed wiping (direct herbicide application to weeds taller than the host crop), has decreased from 36 per cent in 2015 to 11 per cent in 2019.  Other methods used for targeting pesticide application in 2019 included the calibration and maintenance of sprayers used by 15 per cent of growers and technical updates on product efficacy used by four per cent.

Figure 37 IPM: Targeted pesticide application 2015-2019
Figure 37: Bar chart of percentage responses to questions about targeted applications where reduction of dosage or frequency is most common method.

Note: 'Other' in 2019 included regular calibration and maintenance of sprayers and technical updates on product efficacy. 

In addition, 74 per cent of growers in 2019 stated that they followed anti-resistance strategies, a small decrease from 80 per cent in 2015 (Table 34, Figure 38).  Anti-resistance strategies are used to minimise the risk of development of pest resistance.  In 2019, 59 per cent of growers, similar to 2015, minimised the number of pesticide applications used.  Forty eight per cent of growers in 2019, a decrease from 60 per cent in 2015, used a range of pesticides with multiple modes of action.  Forty one per cent of growers used pesticides with multi-site modes of action, an increase from 28 per cent in 2015.  Other growers in 2019 (four per cent) stated that their agronomist selected the best anti-resistance option.

Figure 38 IPM: Types of anti-resistance strategies 2015-2019
Figure 38: Bar chart of percentage responses to questions about anti-resistance strategies where minimising numbers of applications is most common method.

Note: 'Other' in 2019 includes agronomist selects the best anti-resistance option

An important aspect of IPM is monitoring the success of risk management and crop protection practices to continually improve regimes.  Ninety three per cent of growers in 2019 stated that they monitored the success of their crop protection measures, a decrease from 100 per cent in 2015 (Table 34, Figure 39).  Between 2015 and 2019, there has been a decrease in the proportion of growers having a regular review with their agronomist and an increase in the proportion using regular self inspection to monitor their crop protection success.  In 2019, 63 per cent of growers had a regular review with their agronomist to monitor crop protection success, a decrease from 84 per cent in 2015 and 59 per cent of growers conducted regular self inspections of their crops, an increase from 28 per cent in 2015.  There was a similar increase in the use of self inspection to monitor and identify pests from 2015 to 2019 (Figure 34).  However the majority of respondents in both years sought advice from a BASIS qualified agronomist for pest monitoring and identification. Seasonal review of practice, investigating causes of poor efficacy and trapping were used by similar proportions of growers in 2019 and 2015 (30, 22 and 15 per cent respectively in 2019).  Eleven per cent of growers in 2019 used precision technology such as yield mapping, an increase from four per cent in 2015.  Other methods recorded for monitoring success in 2019 included monitoring crop yields (19 per cent of respondents), trialling different methods of control, feedback from the customer and monitoring residue levels within the crops (each four per cent).  Other methods recorded in 2015 included feedback from processors and packers. 

Figure 39 IPM: Monitoring success of crop protection measures 2015-2019
Figure 39: Bar chart of percentage responses to questions about monitoring success of crop protection where regular self-inspection has increased from 2015.

Note: 'Other' in 2019 included monitoring yields, trialling different methods of control, feedback from customer and monitor residue levels. 

'Other' in 2015 included feedback from processors and packers


Contact

Email: psu@sasa.gov.scot