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Which pests and diseases can damage garden plants?

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Curving flower beds of colorful tulips and blue grape hyacinths bordered by green grass and blooming cherry trees at Keukenhof Gardens near Lisse, Netherlands. — gardening Keukenhof Gardens, near Lisse, Netherlands.

In the context of gardening as both an art and a science, maintaining plant health requires vigilance against various biological and environmental threats. Damage to garden plants is primarily categorized into pest infestations and infectious or noninfectious diseases.12

Pests

Garden pests include small creatures such as insects, mites, and eelworms, as well as larger mammals like deer, rabbits, and mice. Specific insect pests, such as plant bugs, feed on plant sap, causing leaves to wither and producing spots that can render fruits unmarketable.23

Infectious Diseases

Infectious diseases are caused by fungi, bacteria, and viruses. Common examples include:24
* Fungal: Powdery mildew, anthracnose, and various wilts.4
* Bacterial: Fire blight, crown gall, and cankers.4
* Viral: Mosaic and spotted wilt.4

Noninfectious Factors

Plants may also suffer from nonparasitic disorders caused by adverse environmental conditions, such as temperature extremes, drought, poor soil aeration, or nutrient deficiencies. These conditions can lead to symptoms like stunting, leaf scorching, and dieback, often mimicking infectious diseases.1

Effective management relies on integrated pest management, which emphasizes prevention through good garden practices—such as pruning, crop rotation, and the use of resistant plant varieties—to minimize reliance on chemical controls.52