DiseasesUnit: Plant Pests

Objectives: 1) Explain diseases as related to plants

2) Describe the types and causes of plant diseases

3) Explain how common plant diseases are identified

4) Identify common plant diseases

5) Describe ways plant diseases are spread

6) Describe ways plant diseases are managed

Plant Disease1) Plant disease- abnormal condition of a living plant that affects a small part or

the entire plant

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

Biotic Abiotic

Detection1) 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.

Common Plant Diseases Gall- Abnormal growth on a plant

Blight- the withering and perhaps death of a plant

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

Common Plant Diseases Rot- the decay of plant tissue

Wilt- disease of the vascular system caused by bacteria

Common Plant Diseases Smut- diseases caused by fungi, dusty spores cover the grain

Stunt- viral disease that causes the plant not to grow

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

How diseases are spread:

Insects and animals (vectors- disease transmitting organism), Soil, water and air, and Machinery

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

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)

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

Biological Management Use of biological intervention to combat pathogens, such as genetic

engineering and natural enemies

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.

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

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.

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.