Pest Management and Fungal Diseases Quiz
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Questions and Answers

Which method is NOT effective in reducing egg-laying adults?

  • Submerging eggs in water
  • Employing kerosene light traps (correct)
  • Utilizing natural predators
  • Using mercury light traps

Which statement about IR1314 is accurate?

  • It is classified as a tolerant variety. (correct)
  • It can be grown in tungro-infested areas.
  • It is specifically recommended for dry conditions.
  • It is a commercially available resistant variety.

Which organism is responsible for killing the eggs of certain pests?

  • Green muscardine
  • Telenomus triptus (correct)
  • Frogs
  • Carabid beetles

What is one of the biological control methods mentioned for pest management?

<p>Feeding on eggs and nymphs by beetles (A)</p> Signup and view all the answers

Which of the following characteristics is true for light traps using mercury bulbs?

<p>They attract a wide range of pest species. (D)</p> Signup and view all the answers

What is the primary symptom of Sheath Blight on leaf sheaths?

<p>Oval gray spots with black brown margins (B)</p> Signup and view all the answers

During which growth stage is Brown Spot most susceptible on seedlings?

<p>Seed germination (C)</p> Signup and view all the answers

What causes the leaf withering seen in Brown Spot infections on leaves?

<p>Fused circular spots on leaves (C)</p> Signup and view all the answers

What is a key visual symptom of Stem Rot on leaf sheaths?

<p>Black irregular lesions near the water line (B)</p> Signup and view all the answers

Where is Sheath Rot primarily found?

<p>At the uppermost leaf sheath enclosing the emerging panicle (A)</p> Signup and view all the answers

What stage of growth is the Sheath Blight most likely to affect?

<p>Heading to maturity (A)</p> Signup and view all the answers

What type of discoloration occurs on grains infected with Brown Spot?

<p>Black spots on glumes and discoloration (A)</p> Signup and view all the answers

Which fungal disease is characterized by irregular lesions with gray centers and brown margins?

<p>Sheath Blight (D)</p> Signup and view all the answers

Which of the following correctly defines a pathogen in the context of plant diseases?

<p>A living organism that causes diseases in plants (A)</p> Signup and view all the answers

What does the term 'epidemic' refer to in the context of plant diseases?

<p>A rapid increase in disease occurrence in a plant population (B)</p> Signup and view all the answers

Which symptom is characteristic of leaf blast caused by Magnaporthe grisea?

<p>Small to spindle-shaped spots with brown borders (D)</p> Signup and view all the answers

At which stage of rice growth is the panicle blast most susceptible?

<p>Booting to heading stage (C)</p> Signup and view all the answers

Which of the following statements about biotic and abiotic agents is correct?

<p>Biotic agents are generally infectious and have the ability to infect plants. (B)</p> Signup and view all the answers

What symptom indicates a black node in the tillering stage of rice?

<p>Black rotten node that breaks later (C)</p> Signup and view all the answers

In which location on the plant are symptoms from panicle blast usually found?

<p>On the nodes of the panicle (B)</p> Signup and view all the answers

Which of the following best describes the seedlings' risk concerning diseases?

<p>Seedlings can suffer from diseases like leaf blast at specific stages. (B)</p> Signup and view all the answers

What is one benefit of intercropping rice with soybean?

<p>Reduces the incidence of green leafhoppers (C)</p> Signup and view all the answers

Which method is suggested to reduce leafhopper populations in rice fields?

<p>Draining water from the field (A)</p> Signup and view all the answers

What characteristic distinguishes the young nymphs of the seed bug?

<p>They are green and slender (A)</p> Signup and view all the answers

What is the effective strategy for applying insecticides to control green leafhoppers?

<p>Incorporate granules into the soil (B)</p> Signup and view all the answers

What environmental factors favor the multiplication of rice bugs?

<p>Evenly distributed rainfall throughout the year (C)</p> Signup and view all the answers

Which of the following organisms is known to specifically kill the eggs of pests in rice?

<p>Small wasps (B)</p> Signup and view all the answers

During which growth stages are rice plants most susceptible to damage from pests?

<p>From flowering to milky stage (C)</p> Signup and view all the answers

What behavior do nymphs exhibit when they are threatened?

<p>Drop to lower parts of the plant (D)</p> Signup and view all the answers

What developmental stage of the rice black bug primarily causes the most damage?

<p>Nymphs (D)</p> Signup and view all the answers

During which life cycle stage do rice black bugs prefer high relative humidity for egg hatching?

<p>Egg stage (D)</p> Signup and view all the answers

Which management option is not effective against rice black bugs?

<p>Granular insecticides (B)</p> Signup and view all the answers

What characteristic primarily distinguishes adult rice black bugs?

<p>Distinct yellowish spots (B)</p> Signup and view all the answers

Which of the following practices is recommended to reduce habitats for rice black bug egg-laying?

<p>Cutting or burning grassy weeds (D)</p> Signup and view all the answers

What is a notable feature of nymphs of the rice black bug?

<p>They have a green abdomen. (A)</p> Signup and view all the answers

What type of varieties can offer resistance to rice black bugs?

<p>Awned (bearded) varieties (A)</p> Signup and view all the answers

Which of the following insects are known to feed on nymphs and adults of the rice black bug?

<p>Lady beetles (B), Grasshoppers (D)</p> Signup and view all the answers

What is the best time of day to apply contact insecticides for high efficacy against larvae?

<p>Late afternoon (D)</p> Signup and view all the answers

Which of the following methods is NOT a form of cultural management for grasshoppers?

<p>Application of chemical insecticides (A)</p> Signup and view all the answers

Which characteristic is NOT true of the short-horned grasshopper?

<p>Their nymphs are fully aquatic (A)</p> Signup and view all the answers

What is a significant consequence of grasshopper damage to emerging flowers on rice plants?

<p>Chaffy grains (C)</p> Signup and view all the answers

In which region is the short-horned grasshopper particularly known to cause crop damage?

<p>Pampanga and Mindanao (A)</p> Signup and view all the answers

What management practice can help reduce grasshopper populations besides flooding?

<p>Sweeping along the bunds (A)</p> Signup and view all the answers

What are the primary roles of small wasps in managing pest populations?

<p>Killing eggs of pests (A)</p> Signup and view all the answers

How long is the life cycle duration of a skipper adult, from egg to adult?

<p>7-12 days (C)</p> Signup and view all the answers

Flashcards

Plant Disease

Any disturbance that affects the normal structure, function, and economic value of a plant.

Symptoms

Visible signs on a plant that indicate a disease, like spots, discoloration, or wilting.

Signs

Direct evidence of a pathogen on the plant, like fungi, bacteria, or insects.

Pathogen

A living or nonliving agent (like a fungus, bacteria, or virus) that causes plant disease.

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Biotic

A living organism (like a fungus, bacteria, or insect) that causes disease.

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Abiotic

Nonliving factors that cause disease, like temperature extremes, drought, or nutrient imbalances.

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Infectious

A disease that can spread from an infected plant to a healthy plant.

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Epidemic

When a disease spreads rapidly through a large plant population.

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Sheath Blight

A fungal disease caused by Thanatephorus cucumeris that affects rice plants, primarily attacking the leaf sheaths.

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Sheath Blight Susceptible Stage

Rice plants are most vulnerable to Sheath Blight during the tillering to heading stage.

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Brown Spot

A fungal disease caused by Cochliobolus miyabeanus affecting rice plants, causing spots on leaves, seedlings, and grains.

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Brown Spot Susceptible Stage

Rice plants are more susceptible to Brown Spot during the tillering stage for leaf infections, seedling stage for seedling infections, and maturity for grain infections.

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Stem Rot

A fungal disease caused by Magnaporthe salvinii that primarily affects the stem and leaf sheaths of rice plants.

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Stem Rot Susceptible Stage

Rice plants are most susceptible to Stem Rot during the late tillering to maturity stage.

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Sheath Rot

A fungal disease caused by Acrocylindrium oryzae, affecting rice plants, primarily attacking the uppermost leaf sheath.

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Sheath Rot Susceptible Stage

Rice plants are most vulnerable to Sheath Rot from the tillering stage to panicle initiation.

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Short-horned Grasshopper

A small, yellow and brown grasshopper with distinctive brown stripes running through its eyes. It can become a locust when in large swarms.

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Where to find Short-horned Grasshoppers?

They are found in all rice environments but are most common in rainfed areas. They prefer dry areas and rice fields near grasslands where they breed.

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Short-horned Grasshopper Damage

They can damage rice at all stages of growth, from eating newly germinated seedlings to causing panicle withering and death.

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Short-horned Grasshopper Life Cycle

They lay eggs on rice foliage or in the soil. Their nymphs are semiaquatic.

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Cultural Control for Short-horned Grasshoppers

Flooding the stubble drowns them, shaving bunds kills egg pods, and sweeping along bunds reduces their numbers.

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Nitrogen Fertilizer Use

Use nitrogen fertilizer wisely. Don't overuse or underuse it. Seek advice from experienced farmers in the area.

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Early Planting for Grasshopper Control

Planting rice early can help avoid grasshopper colonization and damage.

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Modern Rice Varieties

Modern rice varieties can withstand relatively high levels of leaf loss.

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Rice Egg Control

Submerging rice eggs in water for 24 hours prevents them from hatching. This method is a practical and effective way to control rice pest populations.

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Light Trap for Rice Pests

Using light traps with mercury bulbs can significantly reduce the number of adult rice pests, especially those attracted to light.

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Kerosene Light Traps for Rice Pests

Kerosene light traps are not bright enough to attract black bugs, making them ineffective for controlling this specific rice pest.

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Tolerant Rice Variety

A rice variety that can withstand certain pest or disease pressure, but may not be completely resistant.

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Wasps as Biological Control

Small wasps like Telenomus triptus are natural predators of rice eggs, providing a biological control method for rice pests.

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Green Leafhopper (GLH)

A small, green insect that damages rice plants by feeding on sap, causing stunting and yield loss.

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Rice Bug (Leptocorisa oratorius)

A slender, greenish-brown insect that damages rice by sucking sap from the panicles, leading to shriveled, discolored grains.

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GLH Control: Cultural Practices

Methods for controlling Green Leafhoppers that involve manipulating the growing environment, such as crop rotation, intercropping, and water management.

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GLH Control: Biological Control

Using natural enemies, like wasps, water bugs, and spiders, to reduce Green Leafhopper populations.

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GLH Control: Chemical Control

Using insecticides to directly kill Green Leafhoppers.

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Rice Bug Damage: Susceptible Stages

The rice bug is most destructive during specific growth stages, particularly from flowering to the milky stage.

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Rice Bug Habitat

Rice bugs thrive in areas with adequate rainfall, especially in weedy rice fields, wild grasses, and near coconut plantations.

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Rice Bug Identification

Rice bugs can be identified by their slender, greenish-brown body and their distinctive camouflage behavior.

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Rice Black Bug

A shield-shaped insect that feeds on rice plants, causing discolored, shriveled grains and an off-flavor in the rice.

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Rice Black Bug Damage

This bug damages rice plants by sucking sap from developing grains, affecting the quality and taste of the rice.

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Nymphs vs. Adults

Nymphs, the immature stage of the rice black bug, cause more damage than adults.

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Rice Black Bug Egg Laying

Female rice black bugs lay eggs in rows on dry parts of the rice plant, often on dead leaves or stems.

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Rice Black Bug Life Cycle

The rice black bug life cycle includes egg, nymph, and adult stages. Eggs hatch into nymphs, which molt several times before becoming adults.

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Cultural Control

Methods of controlling the rice black bug without using chemicals, such as removing weeds, avoiding staggered planting, and trapping the bugs.

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Biological Control

Using natural predators and parasites to control rice black bugs, such as wasps, long-horned grasshoppers, spiders, and lady beetles.

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Chemical Control

Using insecticides to control rice black bugs, usually applied as foliar sprays or dust formulations.

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Study Notes

Major Pest and Plant Diseases of Rice and Their Management

  • Plant diseases are disturbances disrupting normal structure, functions, and economic value of the plant (host)
  • A plant disease is diagnosed through characteristic manifestations of diseased conditions (symptoms) and visible structures (signs) produced by pathogens.
  • Pathogens are either living (biotic) or nonliving (abiotic) agents. Biotic agents can enter and colonize plant parts and other plants (infectious).
  • A serious outbreak of a disease in a large plant population over time is called an epidemic.
  • The triangle diagram illustrates the disease concept. It involves a susceptible host, a conducive environment, and a pathogen.

Diagnosis of Plant Diseases

  • Plant diseases can be identified by observing the characteristic manifestations of diseased conditions (symptoms) and the presence of visible structures (signs) produced by pathogens.
  • Symptoms can include discoloration, deformities, or other noticeable anomalies in the plant's structure and/or function.

Causal Agents of Plant Diseases

  • The causal agents of plant diseases can be living (biotic), like pathogens, or nonliving (abiotic) agents such as environmental factors like high humidity, temperature, or dryness etc.
  • Biotic causal agents are able to invade and colonize plant parts and other plants (infectious)

Disease Management

  • Utilize plant resistant varieties
  • Manage the environment to reduce root disease issues
  • Reduce plant stress to manage disease susceptiblity
  • Manage nitrogen fertilization appropriately
  • Practice proper field sanitation

Specific Diseases and Their Characteristics

  • Blast (Magnaporthe grisea): This fungal disease presents as spots on leaves(leaf blast), nodes(node blast), and panicles(panicle blast). Susceptible stages range from seedling to tillering to booting to heading.

  • Sheath blight (Thanatephorus cucumeris): This fungal disease affects leaf sheaths above the waterline, characterized by oval gray spots that enlarge with dark brown margins and gray centers

  • Brown spot (Cochliobolus miyabeanus): Brown spots on leaves are common on plants in shaded areas, potash deficient, or saline fields, characterized by small, circular spots that fuse causing leaves to wither. (Susceptible: tillering)

Other diseases:

  • Stem rot (Magnaporthe salvinii): Small, black irregular lesions on leaf sheaths near the water line; stem hollowing out, and many sclerotia are in decaying tissue. (Susceptible: late tillering to maturity).
  • Bacterial leaf blight (Xanthomonas oryzae): Tiny water-soaked spots on lower leaves of seedlings, enlarged spots turning yellow and dry rapidly, and seedling wilting. (Susceptible: seedling).
  • -Bacterial leaf streak (Xanthomonas oryzae):* Fine translucent streaks that enlarge, coalesce (merging lesions), brown affected leaves, and leaf withering, susceptible from tillering to maturity. (Susceptible stage: tillering to maturity)

Other topics:

  • Tungro: A viral disease showing mottled leaves, yellowing, stunting. (Susceptible: seedling to tillering, prevalent by green leafhoppers)
  • Grassy and ragged stunt: A viral disease characterized by stunted plants, twisted leaves, vein swelling, and a pale green to yellow appearance. (Susceptible: seedling to tillering).
  • Mole cricket: Light brown insect, wings do not cover the full abdomen; forelegs are broad and curved, strong teeth-like structures for digging soil; 25-35 mm long.
  • Leaf folder: Light brown night-flying moth, dark terminal band on the outer wings, larvae are transparent green, up to 2.5 centimeters long.
  • Rice skipper: Stout brown butterfly, small white spots on wings; larvae elongated with constriction behind head.
  • Short-horned Grasshopper: Small, yellow and brown insect, 3 cm long, with noticeable stripes running laterally. (Migratory phase-locusts)
  • Army worm: Dark purplish-brown forewings with spots, light-colored lines; whitish hind wings, narrowly banded, 30 mm wingspan.. Larvae are soil-dwelling or hide under ground.
  • Whorl maggot (Hydrellia philippina): Dull-gray adult flies, 1.8-2.3mm long.
  • Rice black bug (Scotinophara coarctata): Brownish black adult, 8-9 mm long, with yellowish spots on the thorax, and has a shield-like appearance.

Management Options

  • Cultural control: Includes practices like bund shaving, leveling fields, collecting insects during land preparation, maintaining standing water, choosing resistant varieties, and optimizing spacing.
  • Biological control: Emphasizes natural enemies of the pests, like wasps, spiders, and various insects that naturally prey on them.
  • Chemical control: Involves the use of insecticides, such as granular and foliar sprays during the most vulnerable crop growth stages.

Note: Data extracted from multiple image sources; the images do not always directly correspond to a single topic and may need careful piecing together.

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Major Pest and Plant Diseases of Rice (PDF)

Description

Test your knowledge on pest management techniques and the symptoms of various fungal diseases affecting crops. This quiz covers biological control methods, specific fungi, and their impact on plants. Challenge yourself to identify key facts and characteristics related to Sheath Blight, Brown Spot, and more.

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