[Biology Class Notes] on Rot Pdf for Exam

Rot is a type of plant disease caused by soil-borne bacteria, fungi. Rots meaning can be stated as any plant decomposition or putrefaction. The decay is usually hard, spongy, watery, or dry in any of the plant parts.

What is Rot? 

To state the different types of rot, let us begin with the basal rot.

Basal Rot

It is a widespread plant disease caused by a variety of bacteria and fungi that can infect flower and crop bulbs. The necessary changes that can be seen in Basal rot are as follows:

1. Shoots are stunted or may fail to emerge.

2. Leaves discoloration varies from yellow to reddish or purplish.

3. Roots are discolored and decayed.

4. The rot starts at the root base, progressing upwards and outward.

5. Rot progresses when stored in warm humid places.

6. Fungal rots are dry to spongy or powdery and moldy.

7. Bacterial rots are moist, soft, mushy, and foul-smelling.

Gray Mold Rot 

This disease usually affects flowers and buds, later infections on fruits, leaves, and stems can occur. The visible changes that can be seen here are:

1. Plants growing in humid areas are caused by fungi in the genus Botrytis.

2. Vegetables, fruits, flowers, and woody plants are susceptible.

3. Gray mold rot is characterized by tan to brown soft spots or blotches.

4. It is covered with dusty mold.

5. It causes seedling, young shoots, and leaves to wither and collapse.

6. Buds, flowers, and fruits become flecked and rotten.

Heart Rot  

It is one of the plant rot diseases of trees, root crops, and celery. Heart rot usually does not affect the living sapwood but does cause structural weakness and lead to broken branches and trunks. This rot disease causes loss to the timber industry, as infected trees are unsuitable for timber. 

To define rotten plants and their characteristics one should look for the following changes in the infected parts:

1. Heart rotting fungi produce discolored, lightweight, soft, spongy, stringy, crumbly, or powdery heart decay.

2. Conks or mushrooms appear at the wounds or trunk base.

3. Heart rot is also caused by certain nutrient deficiencies.

4. A brown to black internal rot of beets, carrots, and turnips are caused by a deficiency of boron.

5. Similar rot of celery, fennel, and parsley is induced by calcium deficiency.

6. This type of heart rot causes crop loss in poor soils.

Root Rot 

Root rot is caused by fungi specially armillaria mellea, Clitocybe tabescens, and Fusarium. The following changes are noticed in root rot affected plants:

1. Plants lose vigor, become stunted, and yellow.

2. They wilt, or dieback and drop some leaves.

3. Plants do not respond to fertilizer and water.

4. Affected trees die gradually, roots decay and are covered with mold or black string-like strands.

Wood Rot 

Wood rot is caused by fungi including species of Daedalea, Fomes, Lenzites, Poria, and Stereum. The following damage is noted in the affected trees:

1. Affected wood is discolored, stained, lightweight, soft, crumbly, or powdery.

2. Damage occurs slowly, usually over a period of many years.

3. Infection occurs through wounds.

4. Mushrooms may form at the trunk base.

5. A fruiting body also known as conks, or mushroom sightings indicates extensive decay.

Symptoms and Signs of Rot Disease

The symptoms of rot disease are similar to many plant infections and diseases. The following signs may include in the rot disease:

1. The symptoms hinder the uptake and transport of water and nutrients from the soil.

2. A thick, medium brown to the black crust of mycelium is found around the infected area.

3. The leaves of affected plants become wilt small or discolored.

4. Affected plants look stunted because of poor growth, develop cranks, or ooze sap.

Symptoms of Plant Disease

Most plant diseases are caused by fungal-like organisms whereas many others are caused by viral and bacterial infections. Plant diseases are non-infectious and include damage from air pollution, nutritional deficiencies, and may grow under less favorable conditions. The following symptoms may be noted while assessment of plant disease:

1. Detectable change in color.

2. Leaf wilting is a symptom of verticillium wilt.

3. Bacterial blight symptoms include brown, necrotic lesions at the leaf margin or the interior of the leaf.

4. Bird’s eyespot on berries.

5. Damping-off of seedlings.

6. Leaf spot

7. Fruit spot

8. Canker

9. Mosaic leaf pattern

10. Plant stunting

11. Crinkled leaves

The symptoms are caused by pathogens. Discussing the above symptoms, you are commonly not seeing the pathogen itself but rather symptoms caused by pathogens.