Plant Problems and Remedies

1. Biotic Problems (Caused by Living Organisms) & Remedies

A. Fungal Diseases & Remedies

1. Powdery Mildew (Erysiphales) – White, powdery fungal growth on leaves.
   ✅ Remedy: Improve air circulation, reduce humidity, apply sulfur, neem oil, or fungicides (myclobutanil, azoxystrobin).

2. Downy Mildew (Peronosporaceae) – Yellow/brown leaf spots with gray mold underneath.
   ✅ Remedy: Increase spacing, apply copper-based fungicides, remove infected leaves.

3. Rusts (Pucciniales) – Orange or brown pustules on leaves and stems.
   ✅ Remedy: Remove infected leaves, apply sulfur-based fungicides, improve drainage.

4. Leaf Spots (Cercospora, Alternaria, Septoria, Colletotrichum) – Circular brown/black spots on leaves.
   ✅ Remedy: Use copper fungicides, remove infected leaves, avoid overhead watering.

5. Blights (Phytophthora, Botrytis, Alternaria) – Rapid leaf, stem, and flower decay.
   ✅ Remedy: Prune affected areas, apply chlorothalonil-based fungicides, improve airflow.

6. Wilts (Verticillium, Fusarium) – Sudden wilting and yellowing of leaves.
   ✅ Remedy: Use resistant varieties, solarize soil, rotate crops, improve soil drainage.

7. Root & Stem Rots (Rhizoctonia, Pythium, Armillaria) – Root decay leading to plant collapse.
   ✅ Remedy: Improve drainage, avoid overwatering, use fungicides like metalaxyl for Pythium.

8. Anthracnose (Colletotrichum) – Sunken lesions on stems, leaves, and fruits.
   ✅ Remedy: Prune affected parts, apply copper-based fungicides.

B. Bacterial Diseases & Remedies

1. Bacterial Leaf Spot (Xanthomonas, Pseudomonas) – Water-soaked spots turning necrotic.
   ✅ Remedy: Apply copper-based bactericides, avoid wet foliage, destroy infected plants.

2. Fire Blight (Erwinia amylovora) – Shoots appear scorched; common in apples and pears.
   ✅ Remedy: Prune infected branches, apply copper sprays during dormancy.

3. Bacterial Wilt (Ralstonia, Clavibacter) – Wilting caused by vascular blockage.
   ✅ Remedy: Use resistant varieties, rotate crops, remove infected plants.

4. Crown Gall (Agrobacterium tumefaciens) – Tumor-like growths on stems and roots.
   ✅ Remedy: Remove infected plants, sterilize tools, use resistant rootstocks.

C. Viral Diseases & Remedies

1. Mosaic Viruses (Tobacco mosaic virus, Cucumber mosaic virus) – Mottled yellow-green leaves.
   ✅ Remedy: Remove infected plants, control aphids and leafhoppers, plant resistant varieties.

2. Leaf Curl Viruses – Leaf rolling and stunting in plants.
   ✅ Remedy: Control whiteflies (primary vectors), plant resistant varieties.

D. Nematode Diseases & Remedies

1. Root-Knot Nematodes (Meloidogyne spp.) – Root galls and stunted growth.
   ✅ Remedy: Use resistant plants, solarize soil, apply neem cake or marigolds.

2. Cyst Nematodes (Heterodera, Globodera) – Yellowing and reduced root function.
   ✅ Remedy: Rotate crops, use cover crops like marigold.

E. Insect & Arthropod Pests & Remedies

1. Aphids (Aphididae) – Sap-feeding insects causing curling and yellowing of leaves.
   ✅ Remedy: Release ladybugs, apply neem oil or insecticidal soap.

2. Whiteflies (Aleyrodidae) – Tiny, white insects that suck sap and spread diseases.
   ✅ Remedy: Introduce parasitic wasps, use sticky traps.

3. Spider Mites (Tetranychidae) – Tiny, web-spinning mites causing stippled leaves.
   ✅ Remedy: Spray with water, apply insecticidal soap or predatory mites.

2. Abiotic Problems (Non-Living Causes) & Remedies

A. Nutrient Deficiencies & Toxicities & Remedies

1. Nitrogen Deficiency – Pale green/yellow lower leaves, stunted growth.
   ✅ Remedy: Apply compost, manure, or balanced fertilizers.

2. Phosphorus Deficiency – Purple/reddish leaves, weak roots.
   ✅ Remedy: Apply bone meal or rock phosphate.

3. Potassium Deficiency – Scorched leaf edges, weak stems.
   ✅ Remedy: Use potassium sulfate or wood ash.

4. Calcium Deficiency – Blossom-end rot in tomatoes, distorted growth.
   ✅ Remedy: Apply gypsum or lime.

5. Magnesium Deficiency – Interveinal chlorosis (yellowing) in older leaves.
   ✅ Remedy: Use Epsom salts (magnesium sulfate).

B. Environmental Stress Factors & Remedies

1. Drought Stress – Wilting, leaf curling, premature leaf drop.
   ✅ Remedy: Use mulch, practice deep watering.

2. Flooding/Waterlogging – Root rot, yellowing leaves, oxygen deprivation.
   ✅ Remedy: Improve drainage, raise planting beds.

3. Cold Stress – Leaf browning, frost damage, slowed growth.
   ✅ Remedy: Use frost covers, plant cold-resistant varieties.

4. Heat Stress – Sunscald, leaf scorch, flower abortion.
   ✅ Remedy: Provide shade, increase irrigation.

5. Light Stress

   • Insufficient Light – Leggy, weak growth, pale leaves.
     ✅ Remedy: Adjust planting locations, use artificial lighting.

   • Excess Light – Bleached, scorched leaves.
     ✅ Remedy: Use shading or relocate plants.

6. Wind Damage – Torn leaves, broken stems.
   ✅ Remedy: Use windbreaks like hedges or fences.

C. Chemical Damage & Remedies

1. Herbicide Injury – Twisted, discolored, or deformed leaves.
   ✅ Remedy: Avoid drift, use targeted application.

2. Pesticide Phytotoxicity – Leaf burn, necrosis from incorrect application.
   ✅ Remedy: Follow correct dosage, apply during cool hours.

3. Fertilizer Burn – Over-fertilization leading to leaf scorch.
   ✅ Remedy: Water thoroughly to leach excess salts.