DEMONSTRATING AND APPLYING AN INTEGRATED APPROACH

In addressing the need for sustainable practice, core to any actions is taking an integrated approach but what does that mean? Just as with the term sustainability, it is important to understand what is meant by an integrated approach and importantly what is not. This third in a series of four articles seek to address this topic in some depth, hopefully producing a simple guide to taking an integrated approach in any amenity situation. We are using primarily the example of weed management but the general approach is applicable to disease and pest management as next month’s article will demonstrate.

Next month we will summarise the key components of an integrated weed management (IWM) plan for operational use but currently we are reviewing the various tools we might draw upon to create the most appropriate integrated approach in the given situation. These have been divided into the following categories:

1. Manual & brushing
2. Thermal
3. Electricity
4. Chemical Methods not including plant protection products
5. Plant Protection Products

Last month we looked at the first three categories. This month’s article addresses the remainder.

CHEMICAL METHODS NOT INCLUDING PLANT PROTECTION PRODUCTS

Within this category of tools available for weed control, I am including the following:

• Acetic Acid and salt
• Biological Control

The term chemical is often misused in the context of managing weeds, pests and diseases. In such contexts, it can be given the narrow definition of pesticides but this is wrong. A chemical is any substance that has a defined composition. Chemicals occur in nature, in what we eat and drink, and, indeed, we are composed and exist because of chemicals. Other chemicals are manufactured as in pesticides and so when considering pesticides in weed, pest and disease management it is strictly accurate to refer to synthetic chemicals, or better, plant protection products. 

Acetic acid and salt

Acetic acid occurs in vinegar but the professional products available for weed control comprise acetic acid along with other ingredients to increase effectiveness of control. It can work very quickly, to eliminate small weeds and is highly effective against weeds that have not become established and do not have energy stores to regrow. The effect of acetic acid on weeds is variable. Much depends on the kind of weed being treated. Repeat applications are often needed to control weeds, and some may never be controlled using this material. It will only kill the parts of the weed it touches. It won't travel through the plant.  It can possibly impact upon wildlife that might be hiding under the leaves and, depending on strength, be corrosive to application equipment. 

The use of salt is very unlikely to be an option to choose. If it is, salt will be absorbed into the soil and prevent future growth, sometimes for a long time. Salt based weed treatments work by desiccating (drying out) plant cells and can be effective in slowly killing and eliminating weeds BUT salts will not biodegrade, and excess amounts kill earthworms, soil bacteria and other microorganisms. Salt-based products can also harm watercourses and soils.

Biological control

The use of biological control techniques is a rapidly expanding area. Initially its application was more related to controlling pests but it is developing quickly across all areas. Biological weed control aims to utilise insects, pathogens or even other plants to do the work of weed management for the land manager. Allelopathy can be regarded as a component of biological control in which plants are used to reduce the vigour and development of other plants. Biological weed control involves the release of organisms that attack the host weeds. The aim of biological control is to shift the balance of competition between the weed and the desired plants in favour of the desired plants and against the weed. The biological control agent, normally a fungus or insect, may not necessarily kill the target weed but should, at the least, reduce its vigour and competitive ability. From a practical point of view, the organism or agent should prevent the weed setting seed or producing other reproductive parts. There is considerable potential for encouraging the use of native biological control agents against weeds and substantial research effort has been put into biological control. Whilst initially seen as an alternative to synthetic chemicals in plant protection products, it is now being more advanced as part of an integrated approach.

Types of biological control includes:

classic biological control

Involves the release of exotic natural enemies to control weeds. It has been successful against weeds like thistles in the US and Australia where weevils (native to Europe) have been introduced onto the thistles. With appropriate developments, some introduced weeds like hogweed, Himalayan balsam and the Japanese knotweeds present ideal candidates for classical biological control. Currently plant protection products including glyphosate are the only really economic and effective solution in these cases.

inundative control

Involves the mass production and release of native natural enemies against native weeds. Work in this area has concentrated on fungal pathogens of plants as they can potentially be applied as sprays in the same way as conventional herbicides (hence their name myco- or bio-herbicides). Soil micro-organisms are often overlooked but are also important as plant pathogens. Several are identified as potential biological control agents, particularly for control of grass weeds such as soft brome, wild oat and foxtail. There is considerable potential for using micro-organisms to manipulate or deplete the soil weed seedbank. The persistence of weed seeds in the soil is the key to their success in continuing to emerge despite repeated control measures over many years. Greater predation or an increase in natural decay would reduce the soil seedbank and hence future weed populations. 

conservation control

Manipulates the habitat around the weeds with the aim of encouraging those organisms that attack the weed. This is a strategy that requires a detailed knowledge of the ecology of the weed habitat, the target weeds and the control agents. One example is the upsurge of interest in looking at encouraging the dock beetle on dock plants by creating conditions that favour the beetle.

allelopathy

Refers to the direct or indirect chemical effects of one plant on the germination, growth, or development of neighbouring plants through the release of allelochemicals, while the plant is growing, or from plant residues as it rots down. Allelochemicals can be released from around the germinating seed, in exudates from plant roots, from leachates in the aerial part of the plant and in volatile emissions from the growing plant. The art is to select the right plants to achieve the desired effect. Several weed species have also been reported to show allelopathic properties. They include couch grass, creeping thistle and chickweed. 

As the number of plant protection products available for weed, pest and disease management are reduced, the search for biological control continues to increase. Readers of this article will be aware of the challenge of leatherjackets and chafer grubs. Biological control in terms of the introduction of nematodes is widely available, albeit requiring a different skill set in application compared to plant protection products.

USE OF PLANT PROTECTION PRODUCTS

Plant protection products can often offer the only practical, cost-effective, sustainable and selective method of managing certain weeds in a range of situations. Because they reduce the need for cultivation, they can prevent soil erosion and water loss, and certain weeds may only be susceptible to one specific plant protection product. However, it is important to use the correct product and application rate for control in a particular weed situation and ensure all label and operator instructions are followed. The aim must be to minimise use by proper targeting of applications at correct dosage rates

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Key factors in using pesticides are:

• Training - ensuring all operators have the required qualifications and, all involved, are kept updated ideally through recognised continuous professional development schemes and programmes. Organisations responsible for delivering control programmes are approved by a quality assurance scheme such as “The Amenity Standard” where they must demonstrate their commitment to best practice and compliance with requirements, minimising risk and ensuring optimum use of pesticides and the correct approaches to weed, pest and disease control.
• Ensuring proper risk assessment - a large amount of amenity pesticide use has proximity to the public and proper, and thorough, risk assessment is essential. This will ensure full compliance with legislative requirements
• Creating and implementing an integrated management plan. The UK National Action Plan requires all users to assess the options for control measures needed so that pesticide use is minimised.
• Correct purchasing & storage of plant protection products. This includes ensuring products are supplied by reputable distributors with a commitment to quality and sustainable practice. Pesticide stores should be built/purchased/converted for the relevant quantities to be held and should follow the guidelines set out by HSE and other relevant bodies. Anyone using professional pesticides should be trained in the safety aspects of such use, required by law. 
• Understanding fully label instructions and their implications in application
• Minimising Use. Every effort should be made to minimise the use of pesticides. This starts with the production of an integrated management plan.
• Properly protecting those involved and the public. The law requires you to make every effort to avoid off target contamination. When spraying in any public areas it is important to always work with due regard for bystander safety. It is very important to reduce spray drift to the absolute minimum. Always risk assess every situation – use the safest technique that will achieve the desired result.  When spraying in or around areas used by children such as schools and play areas, keep use to an absolute minimum. Sports facilities should be sprayed during periods of non-use. When spraying at a specific site, erect warning signs and wherever possible, carry out operations in periods of non-use or close the specific area or facility whilst spraying. Specific examples of sites where extra care is needed would be fine turf surfaces, sports facilities, ornamental gardens and small hard surface areas. 
• Ensure protection of water. It is vital that pesticides are not allowed to contaminate water sources and to avoid any form of run-off at all times when applying pesticides. Know the location of drains, watercourses and vulnerable groundwater.  Site pesticide handling areas carefully away from water sources and drains and do not apply pesticides when it is raining or windy (greater than 4mph) or when rain is forecast within 24 hours to avoid run-off.

Right product at the right time

Where the decision is to use pesticides: - they must be the right product, at the right time - and at the right dose.

In determining the appropriate treatment programme, the key factors are:

1. The right treatment for specific areas
2. Level of control: Have you determined the level of control needed and discussed fully with all involved?
3. Timing: Have you properly considered the timings of treatment to maximise effectiveness?
4. Sensitive Areas: Have you properly identified sensitive areas, for example those close to water courses, boreholes, drains etc.?
5. Pesticide use: Can you fully demonstrate why you need to use pesticides, that you have considered alternatives, and that any treatment programme will be properly targeted?

CONCLUSION

Throughout this process we need to keep coming back to what sustainability really means and its three core components. Taking a balanced and integrated approach to weed management is the best policy and indeed many are almost certainly adopting such approaches without knowing. Adopting sustainable practices need not involve a radical approach, small steps may be all that is needed. Whatever approach is taken to managing weeds needs to be economic, efficient and effective, minimising impact on the environment as much as possible. Managing golf fairways and greens demands proper control of weeds to ensure playing conditions are fit for purpose but, in the rough areas, more emphasis can be put on diversity and encouraging wildlife. Producing conditions which minimise weed problems is also important, all part of a fully holistic or integrated approach.

Next month in the last article of this series, we will seek to bring the information in the past three articles to consider the key practical steps involved in creating an integrated management plan for a specific situation.