Causes of Insect and Disease Infection in Greenhouses

Greenhouses provide a controlled environment for optimum crop production. However, the same favorable conditions often accelerate pest and disease outbreaks. Unlike open fields, enclosed spaces reduce natural predators and create ideal microclimates for pathogens and insects.

Some of the major causes for Insect Infestation in Greenhouses are discussed below:

a. Favorable Microclimate

• Warm and humid conditions support rapid multiplication of aphids, whiteflies, thrips, and mites.
• Absence of natural fluctuations favors continuous breeding cycles.

b. Lack of Natural Enemies: Greenhouses restrict entry of predators and parasitoids that naturally check insect populations in the open field.

c. Continuous Cropping / Monoculture: Growing the same crop repeatedly or year-round supports buildup of specific pests (e.g., whiteflies on tomato).

d. Dense Planting and Poor Ventilation: High plant density leads to poor airflow, making plants more attractive and accessible to pests.

e. Introduction through Planting Material: Infested seedlings, cuttings, or grafts often carry hidden insect stages like eggs and nymphs.

f. Structural Openings: Small openings, cracks, or poorly fitted ventilation nets allow entry of flying insects.