What's the difference between biotic and abiotic diseases?
Written by
Nguyen Minh
Reviewed by
Prof. Charles Hartman, Ph.D.You spot sick plants, and you want to know if it is an infection or environmental stress. I mixed them up when I saw my hydrangeas yellower after heavy rains. Understanding the biotic/abiotic difference is vital, for the treatments differ entirely. If you guess wrong, you could spray fungicide on plants that are starving for nutrients.
Biotic Diseases
- Caused by living pathogens: fungi, bacteria, viruses
- Spread through spores, insects, or contaminated tools
- Symptoms progress and intensify over time
Abiotic Disorders
- Triggered by environmental factors like nutrient gaps
- Remain localized without spreading to nearby plants
- Symptoms appear suddenly after specific stress events
Identify the transmission pattern to identify it. Biotic diseases such as powdery mildew spread indiscriminately through the pair of rose bushes within several days. Abiotic injuries, such as sunscald, affected all plants in one spot. Look for progress: the disease becomes worse while environmental injury is stabilized.
Utilize diagnostic tests whenever possible. For cases where disease is expected, I will send samples to extension labs. When dealing with abiotic problems, first test for factors such as soil pH and nutrient levels. Misdiagnosing issues led me to waste months treating nonexistent diseases, when simply applying lime would have improved the soils.
Address specific solutions based on the type of issue. Biotic concerns benefit from copper sprays and the removal of the infected material affected. Abiotic stress may be mitigated by adjusting irrigation or compost application. I had a wonderful recovery of my citrus trees when I improved the drainage system rather than spraying. The treatment must always be in proportion to the cause.
Read the full article: Comprehensive Guide to Identify Plant Diseases
