Horticulture Principles and Practices

8
Principles and Methods of
Disease and Pest Control
PURPOSE AND EXPECTED OUTCOMES
This chapter is designed to classify the methods of disease and pest control and discuss
the rationale behind their use, their effectiveness, and the environmental consequences
of their use.
After studying this chapter, the student should be able to
1. Discuss the general principles of pest control.
2. Discuss the rationale behind each of the four control strategies.
3. Classify pesticides.
4. Classify insecticides.
5. Classify herbicides.
6. Discuss the strategies for the safe and effective use of herbicides.
7. Describe the equipment used in the application of pesticides.
8. Describe the pros and cons of each pest-control strategy.
240
OVERVIEW
In Chapter 6, we learned that the expressed phenotype depends on the genotype (the kinds
of genes) and the environment in which the genes are expressed (P G E). The environment
(E) should not be limited to the growth factors (light, moisture, temperature, and
nutrients), even though these are the essential components. Biological competitors in the
general environment may compete with useful plants for these growth substances to the
detriment of the latter or destroy tissues and interrupt physical and developmental functions
of cultivated plants. In terms of the environment, some of these competitors are native, or
endemic, to particular areas. Others are imported by a variety of modes.
Diseases and pests must be controlled because they cause economic loss to a
horticultural operation. The loss may come as a result of
1. Increased cost of production (additional inputs)
2. Decreased yield
3. Decreased quality