UK growers need novel strategies 

As the industry continues to lose key chemicals in its armoury for the control of pests and pathogens there is a pressing need to secure alternative strategies and products to ensure sustainable production in UK horticulture. Martin McPherson reports.

Impact of comparative assessment
The crop protection industry over the years has, perhaps not too surprisingly, focused much of its effort in the arable sector. As a result, numerous products remain available on specific crops against economically damaging targets. In some instances, where there continues to be a fairly wide choice of plant protection products (PPPs), the idea of substituting older ‘high risk’ products with new ‘low risk’ alternatives would at first glance, appear very logical from an environmental standpoint. 
    Unfortunately, however, the horticultural sector has not been so fortunate to receive the same level of multinational investment in crop protection research. Growers therefore continue to rely heavily on older products either as existing on-label approvals, by extrapolation through the Long Term Arrangements for Extension of Use or by Specific Off Label Approvals (SOLAs). Removing an older product from the agricultural sector by ‘substitution’ will, in many cases, also have considerable consequences downstream in the horticultural sector. However, re-registration dossiers to allow for extension of use of the new ‘low risk’ alternatives may not necessarily be valid to the diverse array of ‘minor’ or specialist crops and as a result, PPP’s are unlikely to be available in all situations. 
    This is best demonstrated by use of a specific commercial example. Here, downy mildew control in glasshouse lettuce can be compared with blight control in maincrop potatoes. Both target pathogens are air-borne oomycete fungi, that would be expected to be largely controlled with the same PPP’s. The example, set out in full in the conference proceedings, provides a clear demonstration of the complexity and vulnerability of integrated disease control strategies within the horticultural sector. The example presented also highlights some of the efforts that have to be made to maintain effective control of dynamic pathogens such as B. lactucae. Most importantly, it should demonstrate to legislators and other stakeholders the potentially serious consequences for the minor crops industry were comparative risk assessment (CRA) to be implemented without full cognisance of the facts. 

Potential for application of CRA
Practical action
It is evident that novel strategies (ie those not already adopted) to allow growers to deliver produce using alternative pest and disease strategies are not immediately available and considerable investment will be required to achieve progress within the diverse horticultural industry. Rather than actively removing ‘older’ products by ‘substitution’ it is considered more appropriate to adopt a semi-regulatory model. A regulatory assessment to rate products relative to their environmental risk could be added to the product label allowing practitioners in the field to make appropriate decisions relative to the local conditions prevailing at the time. Such a semi-regulatory model would also allow Crop Assurance Schemes, Environment Agencies and others to restrict product choice as appropriate for the specific situation; for example, Groundwater Catchment Zones through the Water Framework Directive.
    Naturally, the replacement of ‘outdated’ PPP’s with new effective ‘low risk’ alternatives must, in the long-term, be a logical progression in both the agricultural and horticultural sectors of the industry. However, it will require considerable financial investment and careful planning to maintain a framework for ‘necessary crop protection’. It is imperative that this includes provision for the various minor, or specialist, crops in the intervening period. 

Education and training needs
Farmers, growers and/or their advisers rarely reach a decision to use a crop protection product without first weighing up the various options available. There is inevitably a natural tendency to use ‘older’ familiar products both through habit and their low cost relative to new products. As economic margins for crop production continue to be squeezed this will further highlight the apparent conflict between the aims of the Thematic Strategy through CRA and the growers priorities in the decision-making process that leads up to application of crop protection products.
    The aim therefore, must be to raise the profile of environmental issues during the decision-making process prior to crop protection application. Greater attention must be paid to effective training especially in improving environmental awareness and the potential impact of PPP’s in the wider environment. Knowledge of the individual products and their environmental performance relative to each other would help informed choice and this must be the starting point for any concerted action to reduce environmental pollution. 

Conclusions

• CRA must be encompassed within a framework of ‘necessary crop protection’
• The horticultural industry continues to be highly reliant on PPP’s authorised for use in the agricultural sector
• Legislative changes through EEC/91/414 (the EU ‘harmonisation’ Directive) and the UK acetylcholinesterase review are already causing a significant loss of ‘older’ active substances
• Revoked active substances and products are already being replaced wherever possible, usually with SOLAs – and this is, in effect, a form of ‘substitution’
• The national product re-registration process within the EU Review Programme will cause further minor use losses yet, at the same time, is likely to perpetuate an uneven ‘playing field’ in the EU
• Any further regulatory reduction in crop protection products through CRA could have a significant socio-economic impact in the minor crops industry and further limit consumer choice
• A broad range of protectant and eradicant PPP’s is a fundamental prerequisite for preventing resistance in pest and pathogen populations. CRA could have a significant, but negative, impact in this area if adopted in any way other than the semi-regulatory model outlined above
• Biological alternatives provide a natural progression to replace older chemical PPP’s, though currently the regulatory burden is economically prohibitive and this creates a significant barrier to their commercialisation
• An alternative ‘fast-track’ system for the rapid authorisation of biological or other ‘low-risk’ products similar to that used in the US is required
• As proposed elsewhere it is recommended that CRA is adopted using a semi-regulatory model whereby PPP’s are rated according to their environmental risk
• CRA would be best implemented at the field level providing appropriate training could be provided
• There will be a need for significant financial support from central government to allow industry to respond and adapt positively to the various legislative changes in the industry

Finally at the current time, and until measures are put in place to address the issues raised here, the UK horticultural industry is not well placed to deliver quality produce through alternative pest and disease control strategies.

Edited presentation to the Pesticide Challenge conference, November 2003, Dr Martin McPherson, Technical Director, Crop Protection Services, Stockbridge Technology Centre Limited, martinmcpherson@stc-nyorks.co.uk

[This article first appeared in Pesticides News No. 58, December 2002, page 16]