Insect and Mite Control on Woody Ornamentals and Herbaceous Perennials

Bulletin 504

Insect and Mite Management Alternatives

Integrated Pest Management

Pest Management versus Pest Eradication

Managing insects and mites which attack our urban ornamental plants has generally relied on the use of pesticides. Whether this is good or bad is beyond the scope of this discussion, but we must ask whether alternative controls are available. Before we can consider the alternatives, we should review our current concept of pest management. Pest management as opposed to "eradication" implies that some pests will always be around. It is the goal of pest management to keep the pest populations down to a level where damage is not overly evident. In field crops, this has generally be termed an economic threshold level. In urban ornamentals, the aesthetic threshold level (the population of a pest which causes noticeable, unacceptable visual damage) is the term to be used.

Integrated Pest Management (IPM) - A Definition

Another common term used is integrated pest management (IPM) which is the selection, integration, and implementation of pest control (biological, chemical or cultural) based on predicted economic, ecological, and sociological consequences. In other words, when we use a pest control we must consider the cost both to the ecosystem and human society. Using the IPM approach, three important concepts must be accepted:

1. No single pest control method will be successful. All of the control options - biological, chemical and cultural must be used.
2. Monitoring (sampling) of the pest is constantly needed in order to evaluate the status (not present, present but not causing aesthetic damage, present and causing aesthetic damage, etc.) of a pest population.
3. Therefore, mere presence of a pest is not a reason to justify action for control.

There has been considerable misunderstanding about IPM, IPM control options and the underlying concepts. Perhaps a look at what IPM is or IPM is not will aid our understanding of these concepts.

What IPM is Not:

1. IPM is not a biological control program though biological control is a useful option. However, biological control is only one of the options. We also have to consider chemical and cultural controls.
2. IPM is not an organic program though organic materials can certainly be used if they do not create economic, environmental or sociological problems.
3. IPM is not a pesticide free program because the chemical control tactic may be warranted. Generally, IPM programs have reduced chemical controls (pesticides) but not eliminated them. It is not necessarily the goal of an IPM program to reduce or eliminate pesticides.
4. IPM is not the least or most expensive method of pest management. Usually, the cost of pest control remains close to original costs. Monitoring and sampling costs are traded for scheduled pesticide applications.

What IPM Is:

1. IPM is a decision making process. Each plant, each year and each habitat is slightly different and programmed controls will not address these differences. Thus, monitoring must be performed and decisions must be made.
2. IPM is a system of pest management decisions based on ecological, economic and sociological values.
3. IPM is a process of pest monitoring and sampling. We must know the status of a pest and whether it really needs a control action or not.
4. IPM is a process which considers all of the control options.

Monitoring

Monitoring pest activity and population levels is the key to successful IPM. Unfortunately, most feel that monitoring must be a complicated and time consuming process where someone must constantly watch each and every plant. This is simply not true. Monitoring of pests in nurseries and landscapes can be done in a multitude of ways - from visual inspection to using temperature-dependent (degree-day) developmental models. Another method of solving the seemingly impossible task of monitoring pests in complex settings is the concept of KEY PLANTS and KEY PESTS:

1. Key Plants are trees, shrubs and flowers which are known to have perennial pest problems. As an example, birch trees always get leafminers, aphids and borers while red oaks rarely get significant pests.
2. Key Pests are those which cause significant damage or may kill trees, shrubs or perennial flowers. These key pests often have special times (windows of opportunity) that they are susceptible to controls. Aphids or galls in oaks are rarely significant enough to warrant controls while peach tree borers in ornamental plums need special attention.

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