When we discuss plant diseases caused by abiotic agents, we’re referring to those triggered by non-living factors that can adversely affect plant health. These factors, though not living or infectious, can still significantly impact the growth and development of plants, leading to visible signs of distress.

A variety of environmental and cultural factors can cause diseases in plants. Since these diseases occur in the absence of pathogens, they do not spread from a diseased plant to a healthy plant.

One common culprit is unfavorable environmental conditions, such as extreme temperatures, frost, drought, or excessive moisture. These can disrupt the delicate balance necessary for plant growth, leading to wilting, leaf scorching, or even the death of the plant.

Additionally, chemical factors, including imbalances in soil pH, nutrient deficiencies, or toxicities, can greatly affect plant health. Soil that lacks essential nutrients like nitrogen, phosphorus, or potassium can result in stunted growth, yellowing of leaves, or poor fruit development.

Physical factors like improper soil drainage, excessive wind, or even mechanical damage can also contribute to plant diseases. Poor soil drainage, for example, can lead to root rot, while strong winds can physically damage plants, making them susceptible to infections.

Furthermore, pollutants like industrial chemicals, heavy metals, or air pollutants can negatively impact plant health. These pollutants can accumulate in plant tissues, interfering with their metabolic processes and compromising their overall vitality.

To counter the impact of abiotic factors, farmers and growers often implement preventive measures. These may include selecting plant varieties that are well adapted to local environmental conditions, improving soil quality through appropriate fertilization and soil amendments, and employing protective measures like mulching to regulate soil temperature and moisture.

Understanding the effects of these non-living agents on plants is crucial in implementing effective strategies to mitigate their impact. By addressing these abiotic factors, farmers can help their crops withstand environmental challenges and ensure the long-term health and productivity of their agricultural endeavors.

Plant Diseases Caused by Abiotic Agents (Non-living, Non-parasitic, or Non-infectious)

1. High or Low Temperatures

When plants or plant parts are exposed to high temperatures for prolonged periods, symptoms of scorching or scalding may develop. Some examples are: sunburn or scorching of leaves and sunscald of fruits (e.g., apples, tomatoes, peppers, and melons).

Similarly, low temperatures, like frost or freeze, can damage the exposed or sensitive organs (buds, flowers, young fruits, etc.) or may kill the entire plant.

Examples include southwest-side damage to trunks of apple trees; frost damage to blossoms and young apple fruits; russet ring (caused by frost) on apple and pear fruits; winter injury to trees; and frost damage to tomatoes, beans, potatoes, etc.

2. High or Low Soil Moisture

Too much moisture due to excessive watering, poor drainage, ponding, or flooding may cause plants to turn yellow and be stunted.

Potted indoor plants, for example, may show poor development or root rots. Seedlings are vulnerable to damping-off caused by soilborne pathogens under these conditions.

In some indoor or greenhouse plants (e.g., geraniums, begonias) growing under warm, humid atmospheric conditions and excessive soil moisture, a condition known as edema (small, wart-like rusty, corky bumps) can develop on the underside of the leaves, and on the stems.

At the other extreme, low moisture or drought conditions can lead to poor development, wilting, and death of plants.

3. High or Low Light Intensity

High light intensity is usually not a problem but low light conditions, especially for indoor plants, can lead to etiolation (spindly or lanky plant growth with chlorotic yellow foliage).

4. Lack of Aeration or Low Oxygen Supply

Low aeration can deprive plant roots of adequate oxygen and can adversely affect their development or even kill the plant.

Inadequate oxygen supply during the storage of potato tubers can lead to the development of a condition called blackheart, the browning, and the death of internal tuber tissue.

5. Air Pollution

Certain chemicals, such as ozone, sulfur dioxide, and nitrogen dioxide are released into the air from factories, power plants, and automobile exhausts. These chemicals can accumulate in the atmosphere in sufficient concentration to cause damage to plants.

Ozone damage appears in the form of mottling, chlorosis, spots, and bleaching of young leaves. This is common in certain regions of the country where there is a high ozone concentration in smog.

For example, ozone damage is frequently found on the leaves of beans, petunias, and grapes. Some of the air pollutants responsible for acid rain cause damage to vegetation in certain regions. In Idaho, however, plant damage due to air pollution is not common.

6. Nutrient Deficiencies

Plants require several majors (nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur) and minor (iron, boron, copper, zinc, etc.) elements for normal growth. Deficiency or lack of any of these essential nutrients results in disease symptoms in the plant.

Specific symptoms depend on the plant species and the deficient nutrient. If not corrected, a prolonged acute deficiency of essential nutrients can lead to the death of the plant.

Common examples of nutrient deficiencies are nitrogen deficiency in beans, iron deficiency in peaches, zinc deficiency in apple trees, and calcium deficiency in apple fruit (bitter pit). In the home garden, the common blossom-end rot of tomato fruit is caused, in part, by calcium deficiency.

7. Mineral Toxicity

The presence of excessive available amounts of certain minerals in the soil can lead to mineral toxicity to the plants. The extent of injury depends on the mineral, its concentration, and the species of the plant.

Excessive amounts of sodium salts in the soil can lead to high pH and to alkali injury (e.g., alkali injury to apple). Plants growing in acidic soils can be injured by aluminum or manganese toxicity.

8. Unfavourable Soil pH

Although many plants can grow in a rather wide range of soil pH, plants growing in soils with unfavorable pH usually show poor growth and mineral deficiency or toxicity symptoms.

For example, iron deficiency symptoms are very common in plants growing in high-pH soils.

Under conditions of high soil pH, iron in the soil becomes unavailable to the plant, thus inducing interveinal chlorosis and yellowing of leaves. The plant may die if the condition remains uncorrected for a prolonged time.

9. Pesticide Toxicity

Some pesticides, if improperly used, can cause serious damage to plants. For example, if wettable sulfur is sprayed (for powdery-mildew control) on a very hot day (above 90 F), it will result in injury to the plant’s phytotoxicity).

However, the most common type of chemical injury to plants is due to soil residues or spray drift of herbicides.

Examples of pesticide toxicity are 2,4-D damage to beans and tomatoes, dicamba (Banvel) damage to vegetables and trees, and glyphosate (Roundup) damage to fruit trees.

Some herbicides used as soil sterilants may leave the soil unsuitable for any plant growth for several years.

10. Improper Cultural Practices

Any cultural practice done in the wrong way or at the wrong time can result in significant damage to plants. Injury can result from improper amounts of chemical fertilizer or pesticide or improper chemical mixes in the spray tank.

Root pruning can result from excessively deep cultivation; distorted and twisted roots can result from the pot-bound conditions of a plant. African violet leaves sprinkled with very cold water develop rings and ring-like patterns that resemble symptoms caused by some viruses.

1 thought on “Plant Diseases Caused by Abiotic Agents (Non-living, Non-parasitic, or Non-infectious)”

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