Diseases

1. Diseases Unit: Plant Pests

2. Objectives: • Explain diseases as related to plants • Describe the types and causes of plant diseases • Explain how common plant diseases are identified • Identify common plant diseases • Describe ways plant diseases are spread • Describe ways plant diseases are managed

3. Plant Disease • Plant disease- abnormal condition of a living plant that affects a small part or the entire plant

4. Types and causes • Biotic and abiotic, both result in heavy loses of food, fiber, and plant material • Biotic caused by a pathogen such as: bacteria, fungi, and viruses • Abiotic caused by elements in plant environment such as: Nutrient deficiencies, weather, climate change, pollution, mechanical damage, and mutations Abiotic Biotic

5. Detection • Disease detection is important for: growers, food processors, lumber and paper manufacturers, horticulturists, and consumers • Symptom- how a plant responds to a disease • Sign- the presence of pathogen structures • These include: leaf discoloration, decay, wilting, deformity, reproductive failure, and dead plants • Laboratory Analysis- used for identifying disease that is not easily distinguishable through symptoms and signs.

6. Common Plant Diseases • Gall- Abnormal growth on a plant • Blight- the withering and perhaps death of a plant

7. Common Plant Diseases • Canker- disease on the bark and in the tissue just beneath it • Leaf Spot- yellowing around dead areas on leaves, stems, and fruit

8. Common Plant Diseases • Rot- the decay of plant tissue • Wilt- disease of the vascular system caused by bacteria

9. Common Plant Diseases • Smut- diseases caused by fungi, dusty spores cover the grain • Stunt- viral disease that causes the plant not to grow

10. Common Plant Diseases • Mosaic disease- viruses that attack cereal grains, color spots, patches or streaks • Damping off- (seedling disease) fungi attacks young seedlings shortly after germination

11. How diseases are spread: • Insects and animals (vectors- disease transmitting organism), Soil, water and air, and Machinery

12. Management of Plant diseases: • Cultural methods focus on prevention such as: • Using disease-free and host resistant seed stock • Using needed soil amendments • Planting properly • Rotating crops • Preventing injury • Sanitation

13. Chemical methods used to prevent and treat disease: • Bactericide- controls disease caused by bacteria (liquid or dry application) • Fungicide- manages fungal diseases (used more commonly)

14. Chemical methods used to prevent and treat disease: • Protectants- used as a barrier to protect plants from disease • Systemic- used to kill pathogens inside the plant because they are absorbed by the plant, over time fungi and bacteria become resistant

15. Biological Management • Use of biological intervention to combat pathogens, such as genetic engineering and natural enemies

16. Physical Management • Much like disease preventing cultural practices, such as soil solarization, which captures radiant heat in the soil that can destroy soil pests especially fungi.

17. Summary: • Plant diseases are abnormal conditions in plants. Diseases can affect a small part or an entire plant. Understanding diseases can aid in utilizing prevention and control of the disease. • 2 types of disease biotic and abiotic • Biotic caused by a pathogen such as: bacteria, fungi, and viruses • Abiotic caused by elements in plant environment such as: Nutrient deficiencies, weather, climate change, pollution, mechanical damage, and mutations

18. Summary: • Symptoms and signs of disease vary but some are easy to spot if you know what to look for such as abnormal leaf color, decay, wilt, deformity, reproductive failure, and dead plants. • Common diseases are: Gall, Blight, Canker, Leaf spot, Rot, Wilt, Smut, Stunt, Mosaic disease, and Damping off • each crop or plant has diseases that target them specifically.

19. Summary: • Diseases are spread by vectors such as insects and animals, soil, water, air, and machinery. • There are several methods to reduce disease: cultural, chemical, biological, and physical control.