Plant Diseases

What Causes Plant Diseases?

Plant diseases are caused by both living (biotic) and non-living (abiotic) factors that disrupt plant health.

Biotic Causes – Pathogens:

• Fungi: Most common; spread by spores and cause leaf spots, mildew, rots, and wilts by blocking water flow.
• Bacteria: Enter through wounds or openings; cause soft rots, blights, and ooze by breaking down plant tissues.
  Viruses: Spread by insects (like aphids); cause mosaic leaves, stunted growth, and fruit deformities by hijacking plant cells.
• Nematodes: Microscopic worms that damage roots, causing galls, poor nutrient uptake, and wilting.

Abiotic Causes:

• Environmental stresses like drought, pollution, poor soil, and chemical exposure weaken plants.

 

Treatments

Farmers and scientists diagnose and manage plant diseases using observation, lab tools, and preventive strategies.

Detection:

• Symptoms include chlorosis (yellowing), necrotic spots, mold growth, wilting, and stunted development.
• Diagnosis may use hand lenses, microscopy, culturing, or molecular tools like PCR.

Prevention:

• Crop rotation disrupts pathogen cycles.
• Planting disease-resistant cultivars.
• Integrated Pest Management (IPM) to reduce insect vectors.

Treatment:

• Apply fungicides or bactericides as needed.
• Remove and destroy infected plants to prevent the spread.

 

Fun Facts

Here are some interesting facts about plant diseases:

• The Irish Potato Famine was caused by a plant disease called late blight.
• Some fungi glow in the dark! Armillaria, also called honey fungus, is bioluminescent and spreads underground.
• Viruses like tobacco mosaic virus can survive for decades on dry surfaces—even after the plant is gone!
• The Panama disease nearly wiped out the original commercial banana (Gros Michel) in the mid-1900s.

 

Review

Let’s quickly recap what we learned about plant diseases:

• What type of microorganism causes most plant diseases? Fungus
• What symptom on a leaf shows that a plant might be sick? Leaf Spots
• What is one way to disrupt pathogen cycles? Crop Rotation
• What spreads many plant viruses? Insects