Impact of Climate on Plant Disease Development

Plant diseases are more common in humid or wet areas with moderate temperatures and on heavily fertilized plants.

Factors like temperature, moisture, wind, light, and soil conditions significantly impact the development of plant diseases.

Each pathogen has a specific temperature range where it grows best.

Temperature affects different stages of pathogens, from spore production to disease development. For example, cold temps may stop infection, but rising temps can make it happen when conditions are also ideal.

Different pathogens have different temperature preferences. Some thrive in cold, others in warm.

Rapid disease development occurs when pathogen temperature is optimal but the host's isn't.

Moisture plays a vital role in disease initiation and spread. This is because moisture is crucial for pathogens to grow and infect hosts.

Temperature influences the visibility of certain diseases. For example, sometimes viral or mycoplasmal symptoms are masked or less noticeable due to specific temperature ranges.

Moisture is essential for fungal spore germination, bacterial activation, and pathogen spread, influencing disease severity and distribution in plants.

Rainfall amount and distribution correlate with disease occurrences, impacting diseases like late blight, apple scab, and downy mildew, all requiring sufficient moisture for development.

Relative humidity strongly affects fungal spore germination and development of storage diseases; high humidity often triggers disease.

Soil moisture level can either favor or hinder the development of specific plant root diseases, including water mold fungi.

A minimum period of continuous leaf and fruit wetting (at least 9 hours) is often necessary for disease infections, particularly with apple scab, depending on temperature.

Powdery mildew infection is actually less likely with free surface moisture.

Maintaining specific relative humidity levels (e.g., 85-90% for sweet potato storage) can prevent some storage rots from developing.

Extreme soil moisture can suppress or enhance different types of plant diseases

Lowering soil oxygen and raising carbon dioxide levels can make plant roots more susceptible to rotting.

Diseases like take-all, charcoal rot, common scab, and onion white rot are worse when soil moisture is low.

Wind carries spores and pathogens, especially fungi and bacteria, causing widespread disease.

Wind-blown rain splashes bacteria from infected plants to healthy plants, increasing spread.

Light intensity and duration can boost or reduce how easy plants are to infect.

Soil acidity (pH) strongly influences the growth of soil-borne pathogens.

Certain pathogens prefer specific soil types (e.g., loam or clay).

Plant nutrition affects how easy a plant is to infect and how well it fights off disease.

High nitrogen levels can increase plant susceptibility to certain diseases like fire blight, rust, and powdery mildew. Low nitrogen levels may also increase susceptibility to other diseases, depending on the plant and pathogen.

Phosphorus can sometimes reduce disease severity (like potato scab) but can also increase the severity of others (like cucumber mosaic virus).

Potassium can lessen disease severity in many cases, but high levels can increase disease for some crops like rice.

Calcium reduces severity of diseases caused by certain root and stem pathogens, but surprisingly increases severity of common potato scab.

Plants getting all the right nutrients in the correct amounts are better protected from disease than those with nutrient imbalances or shortages.

High levels of air pollutants can have a detrimental effect on plants, leading to symptoms and possibly making them more susceptible to pathogens.

Ozone may affect both the pathogen and the plant's disease response.

Imbalances in nutrient levels can dramatically affect the severity of plant diseases and the course they take within the plant tissue.