8. Plant Diseases in the agricultural world.pptx

All about plant diseases that can affect harvested crops

1. Plant Diseases The study of plant diseases is known as plant pathology or phytopathology . It includes the study of the causes of plant diseases, their nature and the environmental factors favoring disease production and control.

2. Generally, a plant is considered healthy if it has the desired inherent traits, if it is grown under the best condition with respect to soil nutrient, moisture, air and light; and if it is free from any insect attack, disease attack, and injury.

3. Diagnosis of Plant diseases. The most effective way to control a disease is when one knows the primary cause of the disease. Plant disease diagnosis consists of discriminating between disease and distinguishing them by their characteristics, symptoms and signs.

4. Signs – is defined as the indication of the presence of the disease. This is usually at the initiation stage of plant disease. Symptoms- are the indication of the evidence of the presence of the disease.

5. Causes of plant disease: Fungi- commonly called molds and are microscopic, multi-cellular, primitive plants devoid of chlorophyll and thus obtain their food through assimilation of nutrients from the substrate or their hosts. The downy mildew disease of corn Rice blast d. anthracnose disease Coffee rust e. phytophthora

6. 2. Bacteria- they are unicellular microorganism devoid of chlorophyll. a. Bacterial wilt of solanaceous plants and banana b. Soft rot of vegetables c. cankers

7. 3. Viruses- they are so small. They can only be seen with the most powerful microscope known as electron microscope. All viruses are parasitic; they can only live and reproduce in other cells, whether plant, animal or microbial. Yellow spots or streaks or the mosaic pattern Stunted growth Curling of twisted leaves Proliferation of twigs at an internode

8. 4. Nematodes – They are tiny eelworms which live freely in the soil and feed on microscopic animals and plants. -causing root sweelings or root knots 5. Psychological disease –these are the cause of abnormality in plants growth brought about by water stress, nutrient deficiency or toxicity.

9. What diseases have you encountered in growing fruit bearing trees? What treatment have you applied? • Fruit rot – bagging, smudging Treatment may be the following ◦ Cultural ◦ IPM ◦Chemical