Major Rice Diseases and their Management - PowerPoint Presentation

Major Rice Diseases and their Management

Learning Outcomes: After attending this module, participants should be able to: Understand the nature of rice diseases, how they develop and spread Know the general principles in disease management Describe distinguishing signs and symptoms and identify major viral, fungal, and bacterial rice diseases Learn management strategies based on IPM principles

Structure: Lesson 1. What is a Disease (Disease Concepts) Lesson 2. General Principles in Disease ManagementLesson 3. Viral Diseases and their Management Lesson 4. Fungal Diseases and their ManagementLesson 5. Bacterial Diseases and their Management

Lesson 1: Disease Concepts Learning Objective: To define what is a Disease, To explain the disease tetrahedron concept To discuss common signs and symptoms of Rice Diseases. Structure: What is a Disease Disease Tetrahedron Signs and Symptoms of Rice Diseases

What is a Disease? A disease is an impairment of the normal physiological functioning of a plant or plant part. It interferes with normal function, structure and economic value. It can be recognized by the associated visible changes on the entire plant or plant parts called symptoms.

Disease Tetrahedron Concept Host Pathogen Environment Time Man

Activity: Signs and Symptoms Objective: To assess the participants ’ knowledge on common signs and symptoms that occur in the field. (Note: show actual specimens) Rice disease symptoms can be categorized in several groups: Overall dwarfing or stunting of the plant, Changes in color, such as yellowing or chlorosis, Necrosis or death of the tissue (leaf spot, blight, streak, scald, etc.) Wilting due to interference in water movement within the plant, Unusual development or transformation of organs (false smut, etc.) Formation of galls or swelling of veins.

Definition of Terms Symptom – a visible or detectable abnormality in the host as a result of the disease Sign – observable evidence or indication of the pathogen; consists of the pathogen or its parts or products; -- this increases the reliability of disease diagnosis

Examples of Symptoms yellowing or chlorosis spotsblight

Examples of Signs Sclerotia and myceliaBacterial ooze

Lesson 2: General Principles in Disease Management Learning Objectives: Explain the General Principles in Disease Management Structure: Disease Management Principles

General Principles in Disease Management Disease management is primarily based on the following principles:Avoidance of the PathogenExclusion of Inoculum plants Eradication of the PathogenProtection Disease resistanceTherapy

Activity: Pest and Disease (Tune: Paru-Parong Bukid) I Yellow stem borer, one egg mass and two dots Stripped stem borer, many line many dots Pink stem borer, lays egg mass on leaf sheath And the white stem borer, with two black antennae   II Green leafhopper, tungro Green leafhopper, yellow dwarf We have zigzag leafhopper, that transmits orange leaf We have brown planthopper too, that transmits grassy stunt And we have the rice bug that sucks the milk of rice

Lesson 3: Viral Diseases and their Management Learning Objectives: To identify the symptoms of viral diseases and their management Structure: Symptom s of Viral Disease s and their Management

Rice Tungro Virus Disease Symptoms stunted growth yellowing (yellow-yellow orange) that starts on the younger leaves slightly reduced tillers caused by 2 types of viruses: Rice Tungro Bacilliform Virus (RTBV) and Rice Tungro Spherical Virus (RTSV) presence of both RTBV and RTSV results to severe symptoms and damage

Rice Tungro Virus Disease Symptoms infected plants occur in patches in the field rice is susceptible during the vegetative phase can be transmitted by green leaf hoppers (GLH) and zigzag leaf hoppers (ZLH) GLH ZLH

Management of Rice Tungro Disease Use of resistant or tolerant varieties against viruses or insect vectors (Ex. NSIC Rc118 and NSIC Rc120) Practice of synchronous planting to minimize spread of the disease from one field to another Proper management of insect vectors Roguing of infected plants while incidence is still low to prevent further spread Plowing under infected stubbles right after harvest Rotation of cultivars with different levels of resistance

Management of Rice Tungro DiseaseNote: For viral diseases, it is more effective to take measures to prevent viral diseases from entering the field than to control the disease after it has appeared. Once a plant is infected by virus it cannot be cured.

Lesson 4: Fungal Disease s and their Management Learning Objectives: To identify the symptoms of fungal disease s and their management Structure: Symptom s of fungal Disease s and their Management

Fungal Disease s and their Management Blast (leaf) Blast (node and neck) Brown Spot Narrow Brown Spot Sheath Blight Sheath Rot Stem Rot Source: http://www.knowledgebank.irri.org/training/fact-sheets/pest-management/diseases/

Rice Blast Leaf blast Source: http://www.knowledgebank.irri.org/training/fact-sheets/pest-management/diseases/ Neck blast Panicle Blast Node blast Collar blast

Brown Spot Brown spot lesions on leaves Source: http://www.knowledgebank.irri.org/training/fact-sheets/pest-management/diseases/

Sheath Blight Source: http://www.knowledgebank.irri.org/training/fact-sheets/pest-management/diseases/ Sheath Blight Symptoms on Leaf Sheath and on Leaves Dindo King M. Donayre PhilRice Negros

Sheath Rot Sheath Rot Symptoms Source: http://www.knowledgebank.irri.org/training/fact-sheets/pest-management/diseases/

Narrow Brown Spot and Stem Rot Narrow Brown Spot Stem Rot

General Management Strategies for Fungal Diseases Use of disease-free seeds since most of fungal diseases are seed-borne (Ex. Brown Spot, Bakanae) Follow recommended seeding rate or planting distance to avoid rapid spread of fungal diseases Practice sanitation at all times by performing regular weeding in the field, levees and irrigation canals to remove possible alternate hosts Observe balance fertilization since some fungal disease are indicators of nutrient deficiencies (Ex. Brown Spot and Sheath Blight – indication of K deficiency) Proper water management. Excessive and continuous water increases RH that favors growth and reproduction of fungus. Proper use of recommended fungicides if necessary

Lesson 5: Bacterial Disease s and their Management Learning Objectives: To identify the symptoms of bacterial disease s and their management Structure: Symptom s and Management Control: Bacterial Blight Bacterial Leaf Streak

Bacterial Leaf Blight Extensive death of leaf tissue starting from the leaf tips and or leaf margins Source: http://www.knowledgebank.irri.org/training/fact-sheets/pest-management/diseases/ Bacterial ooze Dried up bacterial ooze

Bacterial Leaf Streak Source: http://www.knowledgebank.irri.org/training/fact-sheets/pest-management/diseases/ Bacterial Leaf Streak lesions on leaves

General Management Strategies for Bacterial Diseases Fallow the field after harvest and allow the field to dry Use of resistant/tolerant varieties if available Avoid wounding of leaves during transplanting that may serve as entry points of bacteria Practice sanitation at all times by performing regular weeding in the field, levees and irrigation canals to remove possible alternate hosts Avoid excessive Nitrogen application (practice split application of N) and increase use of K fertilizer for healthier growth. Excessive N favors rapid reproduction of bacterial cells.

General Management Strategies for Bacterial Diseases Drain the field to prevent further spread and to minimize reproduction of bacteria In the case of Bacterial Leaf Streak or BLS, grains from infected crops should not be used as seeds for the next planting season because BLS in particular is seed-borne or may be carried through seeds.

Evaluation Activity: Ballot Box Evaluation

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