MCQs On Crop Protection For Agriculture Examinations

1. The parasitic fungus *Puccinia graminis tritici* causes which of the following diseases in wheat?

• a) Loose smut
• b) Leaf blight
• c) Stem rust
• d) Flag smut

2. Which of the following statements best describes the mode of action of systemic fungicides?

• a) They kill pathogens by direct contact on plant surfaces.
• b) They are absorbed and translocated within the plant to protect new growth.
• c) They only inhibit spore germination on the leaf surface.
• d) They act by dehydrating fungal hyphae externally.

3. The economic threshold level (ETL) in pest management refers to the pest density at which:

• a) The pest population causes total crop failure.
• b) The pest population is first detected in the field.
• c) Control measures should be applied to prevent economic loss.
• d) The pest population is below economic injury level.

4. Which of the following is the most effective method for managing bacterial wilt of tomato caused by *Ralstonia solanacearum*?

• a) Application of systemic fungicides
• b) Crop rotation with non-solanaceous crops
• c) Application of nitrogenous fertilizer
• d) Spraying copper-based bactericides

5. Which of the following herbicides is classified as a non-selective contact herbicide?

• a) Glyphosate
• b) Paraquat
• c) Butachlor
• d) Atrazine

6. The disease “rice tungro” is transmitted by which of the following vectors?

• a) Leafhopper
• b) Aphid
• c) Whitefly
• d) Thrips

7. The herbicide 2,4-D primarily controls which type of weeds?

• a) Sedges
• b) Grasses
• c) Broadleaf weeds
• d) Aquatic weeds

8. In insect physiology, the process of shedding the old cuticle to allow growth is known as:

• a) Sclerotization
• b) Metamorphosis
• c) Molting
• d) Pupation

9. A fungal disease characterized by white powdery growth on leaf surfaces is known as:

• a) Downy mildew
• b) Powdery mildew
• c) Leaf spot
• d) Anthracnose

10. The process of pesticide degradation through the action of microorganisms in the soil is known as:

• a) Photodecomposition
• b) Hydrolysis
• c) Microbial degradation
• d) Chemical oxidation

11. The “disease triangle” concept in plant pathology involves interaction among three essential factors:

• a) Pathogen, host, and favorable environment
• b) Host, soil, and light intensity
• c) Pathogen, nutrient, and rainfall
• d) Host, pathogen, and fertilizer level

12. The virus causing mosaic disease in tobacco belongs to which of the following groups?

• a) Tobamovirus
• b) Cucumovirus
• c) Potyvirus
• d) Geminivirus

13. The presence of bacterial ooze on cut surfaces of infected plant tissue is a diagnostic symptom of:

• a) Fungal wilt
• b) Bacterial wilt
• c) Viral mosaic
• d) Nematode gall

14. Which of the following is a seed-borne disease of rice in the Philippines?

• a) Bacterial leaf blight
• b) Rice blast
• c) False smut
• d) Bunt disease

15. Which of the following best explains the term “pathogenicity” in plant pathology?

• a) Degree of damage caused by abiotic stress
• b) Ability of a pathogen to cause disease
• c) Capacity of plants to resist infection
• d) Intensity of infection within an area

16. Which of the following environmental conditions generally favors the development of late blight in potato?

• a) Hot and dry weather
• b) Cool and moist conditions
• c) Low humidity and strong sunlight
• d) Windy and arid environment

17. The resistant variety approach in disease management primarily works by:

• a) Killing the pathogen directly
• b) Reducing susceptibility of the host plant
• c) Changing the environmental conditions
• d) Eliminating inoculum from soil

18. The disease “banana bunchy top” is caused by which type of pathogen?

• a) Fungus
• b) Bacterium
• c) Virus
• d) Phytoplasma

19. The first step in diagnosing a plant disease accurately is to:

• a) Apply chemical treatment
• b) Observe visible symptoms on the plant
• c) Perform a soil nutrient analysis
• d) Conduct pesticide residue testing

20. Quarantine measures in plant protection are primarily intended to:

• a) Enhance yield of infected crops
• b) Prevent introduction and spread of exotic pests and diseases
• c) Reduce cost of disease control
• d) Maintain soil fertility during crop rotation

21. The order Lepidoptera includes insects that are characterized by:

• a) Piercing and sucking mouthparts
• b) Chewing and biting mouthparts
• c) Siphoning mouthparts and scaly wings
• d) Sponging mouthparts and hairy wings

22. The rice black bug (*Scotinophara coarctata*) primarily damages rice by:

• a) Chewing roots
• b) Sucking sap from plant tissues
• c) Boring into stems
• d) Feeding on developing grains

23. Which of the following insect pests of corn is known for producing characteristic “shot holes” on leaves during the seedling stage?

• a) Corn earworm
• b) Corn borer
• c) Flea beetle
• d) Cutworm

24. The golden apple snail (*Pomacea canaliculata*) damages rice mainly by:

• a) Cutting rice tillers at base
• b) Feeding on young seedlings
• c) Attacking panicles at heading
• d) Sucking plant sap during booting

25. Insects that undergo complete metamorphosis exhibit which of the following developmental stages?

• a) Egg, nymph, adult
• b) Egg, larva, pupa, adult
• c) Egg, instar, adult
• d) Egg, maggot, adult

26. Which of the following is a common predator of aphids in agricultural ecosystems?

• a) Lacewing larvae
• b) Whitefly
• c) Thrips
• d) Rice bug

27. Pheromone traps are primarily used in pest management to:

• a) Attract pollinators for crop production
• b) Monitor and trap adult male insects
• c) Repel insect pests from the field
• d) Enhance biological control activity

28. Which of the following statements about Bt crops is true?

• a) They express a bacterial gene toxic to specific insect larvae.
• b) They are resistant to fungal pathogens only.
• c) They repel insects through volatile emissions.
• d) They suppress weeds through allelopathy.

29. The biological control agent *Trichogramma japonicum* is widely used against which type of insect pest?

• a) Stem borers
• b) Aphids
• c) Leaf miners
• d) Cutworms

30. The sterile insect technique (SIT) primarily works by:

• a) Using radiation to sterilize adult pests released into the environment
• b) Applying insecticides that inhibit molting
• c) Feeding insects with hormone-based attractants
• d) Using biocontrol fungi to sterilize eggs

31. Which of the following best describes a “weed” in the context of weed science?

• a) Any plant that completes its life cycle within one season
• b) Any plant growing where it is not desired
• c) A cultivated crop used for animal feed
• d) Any plant having medicinal value

32. Which of the following characteristics is common among most successful weed species?

• a) Low seed production and slow growth
• b) High seed production and dormancy
• c) Dependence on specific pollinators
• d) Poor adaptability to environment

33. The loss in crop yield and quality due to the presence of weeds is primarily because of:

• a) Reduction in soil microorganisms
• b) Competition for nutrients, light, and water
• c) Increase in soil aeration
• d) Increased soil fertility

34. Parasitic weeds such as Striga and Orobanche mainly affect crops by:

• a) Attacking root systems and absorbing nutrients
• b) Producing toxic substances in the soil
• c) Blocking sunlight to crops
• d) Altering soil pH

35. In Philippine rice fields, the major aquatic weed known for rapid vegetative reproduction is:

• a) Echinochloa crus-galli
• b) Cyperus rotundus
• c) Hydrilla verticillata
• d) Imperata cylindrica

36. The effectiveness of crop rotation in weed control is mainly due to:

• a) Decreasing soil organic matter
• b) Interrupting weed life cycles and preventing specialization
• c) Increasing seed dormancy
• d) Promoting uniform weed growth

37. Which type of herbicide kills all vegetation regardless of species?

• a) Selective herbicide
• b) Non-selective herbicide
• c) Residual herbicide
• d) Systemic herbicide

38. The mechanism of action of glyphosate involves inhibition of which plant pathway?

• a) Photosystem I electron transport
• b) Lipid biosynthesis pathway
• c) Shikimic acid pathway
• d) Nucleic acid synthesis

39. Resistance of weeds to herbicides can be minimized by:

• a) Using the same herbicide continuously
• b) Rotating herbicides with different modes of action
• c) Increasing herbicide concentration every season
• d) Applying herbicides at random intervals

40. Integrated Weed Management (IWM) emphasizes:

• a) Exclusive use of herbicides for control
• b) Reliance on mechanical control only
• c) Combination of cultural, mechanical, biological, and chemical methods
• d) Dependence on a single method of control

41. Which of the following best defines a pesticide?

• a) Any substance used to promote plant growth
• b) Any chemical or biological substance intended to prevent, destroy, or control pests
• c) Any fertilizer that enhances soil fertility
• d) Any chemical used exclusively for weed nutrition

42. Wettable powders, emulsifiable concentrates, and granules are examples of pesticide:

• a) Formulation types
• b) Mode of action
• c) Application techniques
• d) Chemical families

43. Organophosphate insecticides act primarily by inhibiting which enzyme in the nervous system?

• a) Amylase
• b) Acetylcholinesterase
• c) Catalase
• d) ATP synthase

44. The concept of “selectivity” in pesticide science refers to:

• a) A pesticide’s ability to kill all organisms equally
• b) The ability of a pesticide to affect target pests while sparing beneficial organisms
• c) The concentration required to achieve 100% mortality
• d) The environmental persistence of a chemical

45. Which of the following best describes “pesticide resistance” in pest populations?

• a) Ability of pests to avoid pesticide exposure through migration
• b) Heritable decrease in sensitivity of pest populations to a pesticide
• c) Temporary recovery of pests after pesticide degradation
• d) Natural immunity of beneficial organisms

46. Which of the following pesticide application methods involves direct treatment of seeds before sowing?

• a) Foliar spray
• b) Soil drenching
• c) Seed treatment
• d) Aerial spraying

47. The persistence of a pesticide in soil primarily depends on its:

• a) Color and odor
• b) Solubility, volatility, and microbial degradation rate
• c) Method of packaging
• d) Price and formulation

48. In the Philippines, pesticide registration and regulation are primarily under the authority of:

• a) Department of Science and Technology (DOST)
• b) Fertilizer and Pesticide Authority (FPA)
• c) Bureau of Plant Industry (BPI)
• d) Department of Agriculture–PhilRice

49. In Integrated Pest Management (IPM), chemical control should be:

• a) Used as the first and only approach
• b) Avoided under all circumstances
• c) Used judiciously as a last resort within an integrated strategy
• d) Applied routinely on a calendar basis

50. The development of biopesticides and nanopesticides primarily aims to:

• a) Increase chemical residues in the environment
• b) Promote sustainable and eco-friendly pest control
• c) Replace organic agriculture practices
• d) Increase pest resistance rates