Plant Diseases

Introduction

• Like animals, plants also suffer from verities of diseases.
• The biological agents that causing diseases to plants are known as pathogens.

• Some of the common plant pathogens are −
  • Viruses
  • Bacteria
  • Fungi
  • Nematodes
• However, some non-pathogenic diseases (in plants) may also occur when the pH value, moisture, humidity, soil, etc. of soil change.

Viral Diseases in Plants

• The following table illustrates the major plant diseases caused by virus −

Disease	Plants Affected
Bud Blight	Soy beans
Curly top	Beans, tomato, sugar beets, etc.
Mosaic leaf	Tomato, tobacco, corn, legume, potato, pea, sugar beet, cucumber, maize, cauliflower, sugarcane, bean, etc.
Yellowing of leaf	Barley, sugar beet, potato, etc.
Spotted Wilt Virus	Tomato, capsicum, etc.
Chlorosis Virus	Tomato, capsicum, etc.

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Bacterial Diseases in Plants

• The following table illustrates the major plant diseases caused by Bacteria −

Disease	Plants Affected
Blights	Vegetable crops, fruit trees, etc.
Bacterial wilts	Corn, tobacco, potatoes, alfalfa, tomatoes, etc.
Bacterial speck	Fruits and leaves of different plants
Cankers	Woody plants
Leaf spot	Cotton, beans, peas, etc.
Soft rots	Fleshy or succulent plant parts
Fire Bligh	Rosebushes, pome fruit trees, etc.

Fungal Diseases in Plants

• The following table illustrates the major plant diseases caused by Fungi −

Disease	Plants Affected
Cankers	Largely woody plants
Downy mildew	Grains, onions, cucumbers, alfalfa, etc.
Ergot	Rye, barley, wheat and other grasses
Powdery mildew	Grains, legumes
Tuber diseases	Potato, sweet potato, etc.
Rusts	Wheat, barley, rye, oats, etc.
Root rots	All types of plants
Scab	Wheat, barley, rye, potato, etc.
Smuts	Oats, barley, corn, wheat, grasses, etc.
Wilts	Potatoes, alfalfa, etc.
Cavity spot	Carrot
Leaf blight	Carrot
Ring spot	Brassicas

Diseases by Nematodes in Plants

• The following table illustrates the major plant diseases caused by Nematodes −

Disease	Plants Affected
Hairy root	Sugar beets, potatoes, soybeans, etc.
Root lesions	Different species of plants get affected
Root-knot	Tomatoes, peanuts, etc.