IPM for beds and borders

An increasing number of local authorities are beginning to question their use of pesticides and many of them are seeking information about alternative methods for managing pest problems.

New briefing paper  

The Pesticides Trust [now PAN UK] has produced a briefing paper Beds and Borders to help both professionals and householders become more aware of less toxic methods of pest management. The healthy growth of plants can be disrupted by pests, diseases and disorders. They spoil the plant's appearance and if left to spread and develop unchecked, may impair the plant's growth and development. Until recently many people thought it was only possible to tackle these problems by having an armoury of pesticides at the ready. This view is beginning to change and many plant growers are becoming aware of the fact that it is possible to maintain healthy, attractive planted areas with little or no use of pesticides.  
    The briefing paper discusses why we have planted areas and what we want of them. It provides guidelines on initial design, soils and selecting plants correctly and information on general maintenance and management, assessment of problems, current methods for control and alternative strategies. There is a list of the most commonly used chemical pesticides with some notes on their uses, and the health and environmental problems that they may cause. There is also a statement on the legal requirements for the use of these chemicals. The appendices include details of contacts and suppliers.
    Any area that is not covered by either turfgrass or hard surface could be classed as a potential area for planting. It is possible to develop planted areas in almost any environment and they can be constructed in parks, gardens, at home, in urban wasteland,  on rooftops, in pedestrian areas and in parking sites. In parks and gardens where space and reasonable soil are already available it is relatively simple.  
    Contaminated land areas pose different problems but these can often be overcome. On sites with no subsurface drainage, it is possible to build up large planting areas which can sustain small trees, shrubs and ground covers. In hostile climates, site measures can be taken to ensure suitable protection for plants and encourage a specific micro-climate to encourage vigorous plant growth. Plants in any of these areas can flourish without depending on pesticides.

Pest problems  
Plant professionals generally agree that correct cultural practices and manipulation of environmental factors will reduce or prevent most pest problems. Selecting appropriate plants for the specific area and soil type along with good drainage and soil fertility, adequate water and aeration will develop vigorous root systems and reduce the impact of heat drought, disease and compaction. When plants are thriving in optimum conditions there is an abundance of beneficial organisms available to out-compete pest aggressors and the plants are more resistant to pest invasion.
    If the plants are unhealthy and in poor growing conditions, they are less able to resist attack. Pest problems then become established and until recently, the usual course of action was to resort to chemicals. Pesticides can be effective but generally only in the short term and persistent problems usually mean that the plants are stressed and trying to live in an unhealthy environment.

IPM  
Integrated pest management (IPM) is an approach that suppresses pest, disease and weed populations with complementary use of cultural, physical, biological and minimal chemical controls. With a greater understanding of how these principles work and an increased knowledge of pesticides, it is often possible to reduce the amount of chemicals used and minimise the risks associated with them.  
    IPM techniques include:  

• selecting plants suited to the local environment and their particular use;  

• maintaining appropriate fertility, soil health and water levels;  

• identifying pests and their natural enemies;  

• monitoring and recording regular samplings of pest and predator populations;  

• setting injury levels, that is, when the size of the pest population warrants treatment;  

• setting action levels, that is, assessing the climatic and other variables in order to predict whether injury levels will be reached within a certain time if no action is taken;  

• an integration of treatment methods that are effective against the pest, least disruptive to natural controls and least hazardous to human health and the environment. 

We hope this briefing paper will help to illuminate the problems associated with the unnecessary use of chemicals and encourage the development of alternative management strategies.

Liz Macfie, Beds and Borders, November 1997, contact the Pesticides Trust [now PAN UK] for details of the briefing.

[This article first appeared in Pesticides News No. 38, December 1997, page 18]