Chapter 11

Integrated Pest Management on Organic Farms

Pest Identification

The first step in any pest management program is to accurately identify the pest, whether you are dealing with an insect, weed, plant disease, or vertebrate animal. This step is essential in determining appropriate and effective IPM decisions. Pesticides and other pest management strategies may be effective for one pest may not be appropriate for another. Some pests cause similar damage. In addition, poor plant growth and damage is not always caused by pests; sometimes these problems are due to environmental and cultural conditions that cannot be remedied with pesticides. If problems are incorrectly diagnosed, inappropriate chemical treatments could be used that will be ineffective and add unnecessary pesticide loads to the environment. Once the pest has been accurately identified and confirmed that it is causing damage, become familiar with its life cycle, habitat requirements, time and location of occurrence, and reproductive habits. Pests may leave signs of their presence or symptoms of characteristic damage on hosts and can help in pest identification. Pest symptoms include such things as insect feeding indicators, discoloration from diseases, or reduced plant growth due to competition with weeds for nutrients. Pest signs are parts of the pest itself or other evidence of their presence. The more you know about a pest, the easier and more successful pest management becomes.

Identifying Insects

Identification is critical to distinguish between insect pests and beneficials. Insect identification is based on morphological features such as the structure of mouthparts, wings, legs, antennae, etc. Some special equipment is required for effective scouting a: sweep net, forceps, and aspirator are needed for collecting samples; vials containing rubbing alcohol are used for killing and preserving collected specimens, and a magnifying lens will help with identification of specimens.

Identifying Pathogens

Several types of microorganisms can cause a reduction in plant health including fungi, bacteria, virus, and nematodes. Identification of these organisms in the field is usually very difficult, and lab identification is often required. Diseases and disorders of plants occur when normal plant function is disrupted. For this reason, pathogens can easily be confused with environmental (non-organism related) stresses. Although symptoms between a disease and an environmental stress are often indistinguishable, they can often be separated by the pattern in which they are distributed within the field.

Pest Monitoring Methods

Various methods are used to monitor pests in the field. The type of method selected will largely depend on the potential pest complex of the plants to be protected. Some pests are somewhat universal and can be monitored using conventional methods such as sticky traps or visual observation of plant parts. Other pests require unique monitoring methods such as the use of a pheromone that is typically very selective for a particular pest species. Since all methods only estimate the number of individuals in the actual population, there is always variation from one sample to the next.

Identifying Weeds

Weeds by definition are plants growing out of place. They compete with desirable plants for limiting resources such as water, nutrients, and sunlight to reduce crop yield and quality. Due to this competition, weed species need to be identified and removed when they are young and have not had time to impact the crop. Weeds are classified based on morphological features of the foliage, stems, and flowers; therefore, visual inspection of the plant is all that is required for identification. A small magnifying lens may aid in the identification of small features of some plants.

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