Horticulture Principles and Practices

development to another. Each of these stages has its unique characteristics
and habits. One stage may be more vulnerable than another to a particular control
measure. The most vulnerable stage should be targeted for controlling the
organism. It is important to know the habits of the organism in order to plan a
control strategy. Certain insects hide on the undersides of leaves. Others inhabit
the soil, and still others live on plant materials. Some insects are nocturnal in
feeding habit, and others feed during the daytime. It has already been stated
that certain insects have chewing mouthparts and others have piercing
mouthparts. Some organisms have or secrete a protective covering, whereas
others do not. These and other biological characteristics and habits are important
in designing effective pest-control strategies.
4. Economic importance. It is economically wasteful of resources and time if it costs
more to control a pest than the returns expected from the enterprise without protection.
In other words, if the pest incidence does not pose an economic threat, the
grower should ignore the pest. Certain pests can completely wipe out a production
operation and must therefore be controlled immediately at the sign of their presence.
5. Choice of method of control. The most effective, economic, safe, and environmentally
sound method of control should be selected after identifying the pest
and assessing the potential damage. It may be found that a combination of
methods rather than one particular method may be most effective. Some methods
are easier to apply than others. Further, some methods may require the use of
special equipment or the hiring of professional applicators.
6. Application. If chemicals are to be used, they must be applied at the correct rate.
Premixed chemicals are available for purchase in certain cases. Otherwise, the user
must follow the instructions provided with the chemical to mix the correct rate.
Timeliness of application is critical to the success of a pest-control method.
To eradicate a pest, it is important to know its life cycle. Certain applications may
destroy the adults without damaging the eggs. By knowing when eggs hatch, an appropriate
schedule can be developed to implement repeated application of the pesticide for
more complete control. The environmental conditions under which application of
a pesticide occurs is critical to its effectiveness. Pesticides should not be applied if
rainfall is expected soon after the application. Further, a calm day is required to contain
chemicals applied as sprays and dusts within the area of intended use.
7. Evaluation. The effectiveness of an application should be evaluated within a
reasonable period after application to determine whether a repeat application is
necessary. Evaluating the impact of pest control on the total operation is
important. Controlling pests is expected to significantly increase productivity and
returns on investment. If this is not the case, the grower should review the
operation and make necessary changes.
8. Record keeping. Keeping records of one’s operations is critical. The only way to
make alternative choices is to have data for comparison. Such a record should include
the type of pesticide, rate of application, cost of application, yield, and net returns.
8.4.2 ENVIRONMENTAL AND SAFETY CONCERNS
To avoid indiscriminate use of pesticides and to protect the environment, laws and guidelines
that govern the use of pesticides are enforced. These laws vary from place to place.
Pesticide manufacturers and governmental agencies conduct extensive tests on pesticides
before they are approved for use. That a pesticide is approved for use does not mean it
may be used in any situation desired. Regional and local factors such as climatic factors,
soil characteristics, and agricultural production may preclude the use of approved
chemicals in certain situations. It is imperative that only legally approved chemicals (with
respect to the particular area) be used. Such information is available through the local
extension service. Local nurseries and vendors often carry only state-approved pesticides.
For the inexperienced grower, it pays to seek expert advice on the correct pesticide to use.
This kind of information is usually only a phone call away and free of charge.
248 Chapter 8 Principles and Methods of Disease and Pest Control