Plant Diseases and Their Management

Some of the major diseases in greenhouse crops are caused by fungi, bacteria, viruses, and nematodes. Greenhouses are designed to protect crops from many adverse conditions, but most pathogens and several pests are impossible to exclude. Windblown spores and aerosols containing bacteria enter doorways and ventilators; soilborne pathogens enter in windblown dust and adhere to footwear and machinery. Aquatic fungi can be present in irrigation water; insects that enter the greenhouse can transmit viruses and can carry bacteria and fungi as well. Once inside a greenhouse, pathogens and pests are difficult to eradicate. Factors favorable to disease development; fungal, bacterial, and viral problems in protected cultivation; and disease management strategy are discussed.