What Is a Plant Disease?

What Is a Plant Disease?

How Do Plant Diseases Arise?

 Any active organism is subject to various diseases, and plants are no exception. When a pathogen attacks a plant, the normal function and growth structure of the plant is disrupted, which in turn leads to pathological symptoms such as the yellowing of leaves and rotting of the roots.

 There are many causes of plant diseases; environmental climate change, drought or flooding, temperature extremes, soil pH, or bacteria to name a few.

 This article compiles a few of the most common plant diseases and teaches you how to quickly identify the disease and help restore your plants to health.

Types Of Plant Diseases 

 Plant diseases are caused by 3 main types of pathogens: viruses, fungi, and bacteria.

Viral Plant Diseases

 Viruses and bacteria are among the natural enemies of plants, and it is difficult to save plants after infection. Viruses can be transmitted through asexual reproduction, seeds, pollen, insects, and soil. Generally, plant diseases caused by viruses are misinterpreted as natural physiological defects of plants and are therefore more difficult to detect or control. Some of the common types of virus diseases are as follows.

Mosaic virus - This is a plant disease transmitted by aphids and usually has the appearance of yellow spots or streaks all over the leaves. Crops such as tomatoes, potatoes, squash, and eggplant are susceptible.

Roll-top virus - As the name implies, this virus causes plant leaves to curl and is typically caused by beet leafhoppers. Plants most susceptible to the curly top virus include tomatoes, spinach, and peppers to name a few.

Spotted wilt - the virus is spread by an insect called thrips and infects plants; mainly as irregular purple-brown or red and green streaks on the leaves.

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Fungal Plant Diseases

 Michigan State University Extension has confirmed that 85 percent of plant diseases are caused by fungal pathogens. Fungi can enter plants quickly through natural openings (stomata, pruning, harvesting, and insect nibbles).

Powdery mildew - caused by a fungus in the soil. Infected plants show a white powdery substance on the surface of their leaves. It mainly affects apples, grapes, strawberries, daisies, and roses.

Root rot - The pathogens of this disease multiply in moist, warm environments. They prevent the plant from absorbing oxygen by attacking the root system and eventually cause the roots to turn black and rot. Root rot is easily induced by too much soil moisture.

Rust - A type of plant disease caused by rust fungus parasites. The main manifestation is the yellowing of the leaf surface until it is covered with small yellow spots. It mostly occurs in herbaceous plants and roses.


Bacterial Plant Diseases

 Among the pathogens of plant diseases, bacteria is the least common one. It can infect plants through natural openings, and spread by insects or birds, and this bacterial disease is difficult and fatal to treat.

Leaf spot disease - A common disease that causes discoloration, lesions, and black spots on leaves due to bacterial attack on plant leaf tissue. It is most common in cabbage, cucumber, and Brassica plants.

Soft rot - This disease invades mainly with the help of crop wounds and occurs with the juicy or fleshy tissues of plants and causes decay of plant tissues or organs. The primarily affected plants are carrots, potatoes, eggplants, and other succulent crops, as well as tomatoes, lettuce, onions, and other brassica plants.

Ulcers - mostly occur in woody landscape plants and manifest as depressions, swellings, ruptures or dead zones in plant stems, limbs, or trunks. Major plants affected include cherries, plums, and apricots.

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How To Prevent Plant Diseases

 There are different preventive measures for different types of plant diseases. However, proper watering can prevent most plant diseases.

 Overwatering can cause plant roots to be under waterlogged soil, which creates a good living environment for fungal growth. To avoid overwatering plants, use a soaker hose to allow the water to slowly seep into the soil and reach the plant roots directly, minimizing the risk of overwatering.

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 In addition, overhead watering can result in a growing environment with high humidity and low air circulation. Using a tool that waters directly to the roots, such as a soaker hose or other garden watering kit, can avoid splashing water on the leaves of the plants and reduce various fungal and bacterial infections.


 Plant diseases are inevitable, but advanced knowledge and proper prevention can minimize plant loss. By knowing your pathogen, you can know how fast it spreads and how harmful it is, which helps you take timely measures to help your plants grow healthily.

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