Horticulture Principles and Practices

SUMMARY
Because of their enclosed nature, greenhouses have specific pest problems. The most
common insect pests include aphids, fungus gnats, leaf miners, mealybugs, mites, scale
insects, slugs, snails, thrips, whiteflies, and caterpillars. Common diseases include a
variety of viral and bacterial problems and fungal diseases (e.g., powdery mildew,
Botrytis blight, root rot, damping-off, Verticillium wilt, and nematodes). Because of the
enclosed condition, pesticide formulations for greenhouses such as smokes, fogs, and
aerosols are suitable for use.
When controlling pests, it is important to know the life cycle of the organism, the
residual life of the chemical to be used, and the pesticide’s mode of action. The environment
in the greenhouse can be controlled and monitored to reduce pest incidence. Further,
observance of good sanitation and hygiene, as well as sterilizing growing media,
tools, and other greenhouse structures, reduces the incidence of disease.
REFERENCES AND SUGGESTED READING
Bohmont, B. L. 1997. The standard pesticide user’s guide, 4th ed. Englewood Cliffs,
N.J.: Prentice Hall.
Boodley, J. W. 1996. The commercial greenhouse, 2d ed. Albany, N.Y.: Delmar.
Cravens, R. H. 1977. Pests and diseases. Alexandria, Va.: Time-Life.
Dixon, G. R. 1981. Vegetable crop diseases. Westport, Conn.: AVI Publishing.
Klingman, G. C., F. M. Ashton, and L. J. Noordhoff. 1982. Weed science: Principles
and practices, 2d ed. New York: John Wiley & Sons.
Nelson, P. V. 1985. Greenhouse operation and management, 2d ed. Retson: Retson
Publishing.
Prone, P. 1978. Diseases and pests of ornamental plants, 5th ed. New York:
John Wiley & Sons.
OUTCOMES ASSESSMENT
1. In disease control, prevention is better than cure. Discuss, giving specific
examples, how diseases may be prevented in horticultural production.
2. Discuss specific methods that may be used to reduce or eliminate the presence
of a pathogen’s inoculum during horticultural production.
3. Discuss the concept of integrated pest management as a pest-control strategy.
4. Discuss the pros and cons of the use of pesticides in crop production. What can
a producer do to minimize the adverse effects of the use of pesticides?
5. Describe the information one can obtain from a pesticide label.
6. If a producer does not want to use pesticides in crop production, suggest an
alternative approach that may be adopted to control pests.
280 Chapter 8 Principles and Methods of Disease and Pest Control