1Which of the following is considered a pre-existing structural defense mechanism in plants?
A.Formation of cork layers
B.Deposition of gums
C.Thickness of the cuticle
D.Production of phytoalexins
Correct Answer: Thickness of the cuticle
Explanation:Pre-existing structural defenses are physical barriers present before infection. The thickness and quality of the cuticle and wax layers act as the first line of defense against pathogen penetration.
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2Phytoalexins are low molecular weight antimicrobial compounds that are:
A.Present in healthy plants constitutively
B.Synthesized de novo after infection or stress
C.Transported from the roots to the leaves
D.Proteins produced by the pathogen
Correct Answer: Synthesized de novo after infection or stress
Explanation:Phytoalexins are antimicrobial substances synthesized de novo by the plant in response to infection or stress. They are not pre-existing.
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3The formation of tyloses in xylem vessels is a defense mechanism primarily against which type of pathogen?
A.Leaf spot fungi
B.Vascular wilt pathogens
C.Powdery mildews
D.Root knot nematodes
Correct Answer: Vascular wilt pathogens
Explanation:Tyloses are balloon-like outgrowths of parenchyma cells into xylem vessels that block the spread of vascular wilt pathogens (like Fusarium or Verticillium) through the water-conducting tissue.
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4Which group of Pathogenesis-Related (PR) proteins exhibits -1,3-glucanase activity?
A.PR-1
B.PR-2
C.PR-3
D.PR-5
Correct Answer: PR-2
Explanation:PR proteins are classified into families based on function. PR-2 proteins are characterized by -1,3-glucanase activity, which degrades fungal cell walls.
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5The rapid, localized death of plant cells at the site of infection to restrict pathogen spread is known as:
A.Systemic Acquired Resistance (SAR)
B.Hypersensitive Response (HR)
C.Chlorosis
D.Etiolation
Correct Answer: Hypersensitive Response (HR)
Explanation:The Hypersensitive Response (HR) is a programmed cell death mechanism that sacrifices a few cells to isolate the pathogen and prevent it from spreading to healthy tissue.
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6Which principle of plant disease management involves preventing the entry of a pathogen into an area where it does not typically exist?
A.Eradication
B.Exclusion
C.Protection
D.Therapy
Correct Answer: Exclusion
Explanation:Exclusion prevents the introduction of inoculum into a pathogen-free area. An example is plant quarantine.
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7Which of the following practices is an example of Eradication?
A.Seed certification
B.Plant Quarantine
C.Crop rotation
D.Breeding resistant varieties
Correct Answer: Crop rotation
Explanation:Eradication aims to reduce or eliminate inoculum that has already established. Crop rotation starves soil-borne pathogens by removing their host plants.
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8The application of a chemical barrier on the plant surface before the pathogen arrives falls under which principle?
A.Avoidance
B.Therapy
C.Protection
D.Exclusion
Correct Answer: Protection
Explanation:Protection involves placing a chemical or physical barrier between the host and the pathogen to prevent infection (e.g., prophylactic fungicide sprays).
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9Who discovered the Bordeaux mixture in 1885?
A.Prevost
B.P.M.A. Millardet
C.Tillet
D.Anton de Bary
Correct Answer: P.M.A. Millardet
Explanation:P.M.A. Millardet discovered the Bordeaux mixture while studying Downy mildew of grapes in France.
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10What is the standard chemical composition of Bordeaux mixture?
A. + Lime + Water
B. + Sodium Carbonate + Water
C. + Lime + Water
D.Copper Oxychloride + Lime
Correct Answer: + Lime + Water
Explanation:Bordeaux mixture is a reaction product of Copper Sulphate (), Lime (), and Water.
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11In the classification of fungicides, Sulfur belongs to which chemical group?
A.Organophosphates
B.Inorganic fungicides
C.Dithiocarbamates
D.Antibiotics
Correct Answer: Inorganic fungicides
Explanation:Sulfur and Copper compounds are classified as Inorganic fungicides. Sulfur is widely used against powdery mildews.
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12Which of the following is a systemic fungicide?
A.Mancozeb
B.Captan
C.Carbendazim
D.Thiram
Correct Answer: Carbendazim
Explanation:Carbendazim is a systemic fungicide belonging to the benzimidazole group, meaning it is absorbed and translocated within the plant.
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13Burgundy mixture differs from Bordeaux mixture because it uses which compound instead of lime?
A.Sodium hydroxide
B.Sodium carbonate (Washing soda)
C.Ammonium carbonate
D.Calcium carbonate
Correct Answer: Sodium carbonate (Washing soda)
Explanation:Burgundy mixture is composed of Copper Sulphate and Sodium Carbonate () instead of lime.
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14Which fungicide is specifically effective against Oomycetes (e.g., Downy mildews, Phytophthora)?
A.Metalaxyl
B.Carbendazim
C.Sulfur
D.Tebuconazole
Correct Answer: Metalaxyl
Explanation:Metalaxyl (an acylalanine) is highly specific and effective against Oomycetes fungi like Phytophthora and Pythium.
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15Mancozeb is a coordination product of zinc ion and manganese ethylene bisdithiocarbamate. It belongs to which group?
A.Benzimidazoles
B.Dithiocarbamates
C.Triazoles
D.Strobilurins
Correct Answer: Dithiocarbamates
Explanation:Mancozeb is a prominent member of the Dithiocarbamate group of fungicides.
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16The fungicide Carboxin (Vitavax) is primarily used for the control of:
A.Powdery mildews
B.Smuts and Bunts
C.Leaf spots
D.Bacterial blights
Correct Answer: Smuts and Bunts
Explanation:Carboxin was the first systemic fungicide developed specifically for controlling Basidiomycetes, particularly Smuts and Bunts via seed treatment.
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17Which antibiotic is most commonly used to control bacterial plant diseases?
A.Penicillin
B.Streptomycin sulphate
C.Griseofulvin
D.Cycloheximide
Correct Answer: Streptomycin sulphate
Explanation:Streptomycin sulphate (often combined with tetracycline) is the standard antibiotic used against bacterial diseases like Citrus Canker and Bacterial Leaf Blight of Rice.
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18The mode of action of Benzimidazole fungicides (e.g., Benomyl) involves:
A.Inhibition of ergosterol biosynthesis
B.Inhibition of mitosis (binds to tubulin)
C.Inhibition of respiration
D.Inhibition of chitin synthesis
Correct Answer: Inhibition of mitosis (binds to tubulin)
Explanation:Benzimidazoles bind to -tubulin, preventing microtubule assembly and thereby inhibiting nuclear division (mitosis) in fungi.
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19Triazole fungicides (e.g., Propiconazole) function by inhibiting the biosynthesis of:
A.Chitin
B.Cellulose
C.Ergosterol
D.Proteins
Correct Answer: Ergosterol
Explanation:Triazoles are Demethylation Inhibitors (DMIs) that block the biosynthesis of ergosterol, a vital component of the fungal cell membrane.
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20What does the abbreviation WP stand for in fungicide formulations?
A.Water Packet
B.Wettable Powder
C.Wet Particle
D.Water Proof
Correct Answer: Wettable Powder
Explanation:WP stands for Wettable Powder, a formulation applied as a suspension after mixing with water.
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21Which formulation consists of an active ingredient dissolved in an organic solvent with an emulsifier?
A.Wettable Powder (WP)
B.Dust (D)
C.Emulsifiable Concentrate (EC)
D.Granules (G)
Correct Answer: Emulsifiable Concentrate (EC)
Explanation:EC (Emulsifiable Concentrate) is a liquid formulation where the chemical is dissolved in a solvent and forms an emulsion (milky appearance) when mixed with water.
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22Substances added to fungicide sprays to improve spreading, sticking, or wetting are collectively called:
A.Adjuvants
B.Inert ingredients
C.Fillers
D.Safeners
Correct Answer: Adjuvants
Explanation:Adjuvants (surfactants, stickers, spreaders) are added to improve the physical properties and efficacy of the spray solution.
Explanation:Cheshunt compound is a mixture of 2 parts Copper sulphate and 11 parts Ammonium carbonate, used for soil drenching.
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24Which of the following is a contact (non-systemic) fungicide?
A.Metalaxyl
B.Captan
C.Propiconazole
D.Carbendazim
Correct Answer: Captan
Explanation:Captan is a non-systemic, protectant fungicide (Phthalimide group) that remains on the plant surface.
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25The fungicide group Strobilurins (e.g., Azoxystrobin) was originally derived from:
A.Bacteria
B.Wood-rotting mushroom
C.Marine algae
D.Synthetic polymers
Correct Answer: Wood-rotting mushroom
Explanation:Strobilurins are derived from the mushroom Strobilurus tenacellus and act by inhibiting mitochondrial respiration.
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26In the context of safe handling, LD refers to:
A.Lethal Dose that kills 50% of the test population
B.Low Dose applied at 50 days
C.Last Date of application
D.Legal Duration of 50 hours
Correct Answer: Lethal Dose that kills 50% of the test population
Explanation:LD stands for Lethal Dose 50%. It represents the acute toxicity of a chemical; a lower value indicates higher toxicity.
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27What is the PHI (Pre-Harvest Interval)?
A.Time between sowing and harvesting
B.Time between the last pesticide application and harvest
C.Time required for fungicide to dissolve
D.Time between two fungicide sprays
Correct Answer: Time between the last pesticide application and harvest
Explanation:PHI (Pre-Harvest Interval) is the mandatory waiting period between the last chemical application and the harvest of the crop to ensure residue levels are safe.
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28Which application method is most suitable for controlling seed-borne pathogens?
A.Foliar spray
B.Soil drenching
C.Seed treatment/dressing
D.Stem injection
Correct Answer: Seed treatment/dressing
Explanation:Seed treatment coats the seed with fungicide, directly targeting seed-borne pathogens and protecting the seedling.
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29Solarization is a method of soil disinfestation that primarily utilizes:
A.Chemical fumigants
B.Solar energy/Heat
C.Ultraviolet radiation
D.Freezing temperatures
Correct Answer: Solar energy/Heat
Explanation:Soil solarization involves covering moist soil with transparent polyethylene sheets during summer to trap solar heat, killing soil-borne pathogens.
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30Phenolic compounds like catechol and protocatechuic acid in onion scales provide resistance against:
A.Fusarium oxysporum
B.Colletotrichum circinans (Smudge)
C.Alternaria porri
D.Peronospora destructor
Correct Answer: Colletotrichum circinans (Smudge)
Explanation:Red onion scales contain catechol and protocatechuic acid, which are toxic to Colletotrichum circinans, the cause of onion smudge. White onions lack these and are susceptible.
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31Which of the following is an example of an Organotin fungicide?
A.Fentin hydroxide
B.Zineb
C.Thiram
D.Dodemorph
Correct Answer: Fentin hydroxide
Explanation:Fentin hydroxide and Fentin acetate are organotin compounds used to control diseases like potato blight and tikka disease of groundnut.
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32The process of removing and destroying diseased plant parts (like rogueing) is known as:
A.Sanitation
B.Quarantine
C.Immunization
D.Avoidance
Correct Answer: Sanitation
Explanation:Sanitation involves hygienic practices, such as removing infected debris or rogueing diseased plants, to reduce the source of inoculum.
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33Antibiotics like Kasugamycin are specifically used to control:
A.Wheat Rust
B.Rice Blast
C.Downy Mildew
D.Powdery Mildew
Correct Answer: Rice Blast
Explanation:Kasugamycin is an antibiotic/fungicide effectively used against Magnaporthe oryzae, the causal agent of Rice Blast.
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34Which structural defense involves the deposition of suberin to seal off infected areas?
A.Tyloses
B.Cork layers
C.Gum deposition
D.Abscission layers
Correct Answer: Cork layers
Explanation:Formation of cork layers involves the suberization of cells to create a barrier that blocks the spread of the pathogen and flow of toxins.
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35If you need to prepare 500 liters of spray solution with a concentration of 0.2% using a fungicide (100% a.i.), how much fungicide is required?
A.1 kg
B.2 kg
C.500 g
D.100 g
Correct Answer: 1 kg
Explanation:.
.
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36The systemic fungicide Fosetyl-Al is unique because it is translocated:
A.Only upward (Acropetal)
B.Only downward (Basipetal)
C.Both upward and downward (Symplastic and Apoplectic)
D.It is not systemic
Correct Answer: Both upward and downward (Symplastic and Apoplectic)
Explanation:Fosetyl-Al (Aliette) is one of the few fungicides that is truly ambimobile, moving both acropetally (up) and basipetally (down).
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37Which color code on a fungicide label indicates 'Extremely Toxic'?
A.Red
B.Yellow
C.Blue
D.Green
Correct Answer: Red
Explanation:The toxicity triangle on labels uses Red for extremely toxic, Yellow for highly toxic, Blue for moderately toxic, and Green for slightly toxic.
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38The biochemical defense mechanism involving the 'Burst' of reactive oxygen species (ROS) is called:
A.Oxidative burst
B.Photosynthetic burst
C.Respiration spike
D.Lignification
Correct Answer: Oxidative burst
Explanation:Oxidative burst is the rapid release of Reactive Oxygen Species (superoxide, hydrogen peroxide) which kills pathogens and signals further defense responses.
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39What is the primary mode of action of Sulfur fungicides?
A.Interference with electron transport in respiration
B.Inhibition of DNA synthesis
C.Inhibition of cell wall formation
D.Disruption of mitosis
Correct Answer: Interference with electron transport in respiration
Explanation:Elemental sulfur acts as a hydrogen acceptor, interfering with the electron transport chain in fungal respiration (specifically converting to which is toxic).
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40Which method of application involves applying the chemical in the furrow at the time of sowing?
A.Soil Drenching
B.Soil Application
C.Foliar Spray
D.Slurry treatment
Correct Answer: Soil Application
Explanation:Soil Application generally refers to applying granules or dusts to the soil (furrows or broadcast) to control soil-borne pathogens or nematodes.
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41Which of the following is an example of a Prohibitin (Pre-formed biochemical defense)?
A.Phytoalexin
B.Catechol
C.PR-Proteins
D.Lignin
Correct Answer: Catechol
Explanation:Catechol in red onions is a classic example of a prohibitin—an antimicrobial compound present in the plant before infection.
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42In fungicide formulations, 'Slurry' refers to:
A.A dry dust application
B.A thick suspension of wettable powder in water used for seed treatment
C.An oil-based spray
D.A gas fumigant
Correct Answer: A thick suspension of wettable powder in water used for seed treatment
Explanation:A slurry is a semi-liquid mixture created by mixing a wettable powder with a small amount of water, typically used to coat seeds efficiently.
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43Chaubatia paste is mainly used for:
A.Seed treatment of wheat
B.Dressing pruning cuts in apple/stone fruits
C.Soil fumigation
D.Foliar spray on rice
Correct Answer: Dressing pruning cuts in apple/stone fruits
Explanation:Chaubatia paste (containing Copper Carbonate, Red lead, and Lanoline/Linseed oil) is a wound dressing fungicide developed in India for apple trees.
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44The active ingredient in Thiram belongs to which chemical group?
A.Dithiocarbamates
B.Copper compounds
C.Organochlorines
D.Benzimidazoles
Correct Answer: Dithiocarbamates
Explanation:Thiram is a Dimethyl dithiocarbamate, widely used as a seed protectant.
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45Which of the following is considered a 'General purpose' or 'Multi-site' inhibitor?
A.Mancozeb
B.Metalaxyl
C.Benomyl
D.Carboxin
Correct Answer: Mancozeb
Explanation:Mancozeb is a contact fungicide with multi-site activity, making it difficult for fungi to develop resistance against it compared to single-site systemic fungicides.
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46The accumulation of Lignin in cell walls in response to infection is a:
A.Pre-existing structural defense
B.Induced structural defense
C.Pre-existing biochemical defense
D.Systemic viral defense
Correct Answer: Induced structural defense
Explanation:While some lignin exists normally, rapid lignification (induced structural defense) hardens cell walls to prevent pathogen enzyme degradation and penetration.
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47Validamycin A is an antibiotic primarily used against:
Explanation:Validamycin is highly effective against the soil-borne fungus Rhizoctonia solani, which causes sheath blight in rice.
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48When handling fungicides, which personal protective equipment (PPE) is essential to protect the respiratory tract?
A.Rubber boots
B.Gloves
C.Respirator/Mask
D.Goggles
Correct Answer: Respirator/Mask
Explanation:A Respirator or Mask is specifically designed to prevent the inhalation of toxic dusts or vapors.
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49In the context of chemical combinations, a synergistic effect means:
A.The mixture is less effective than individual components
B.The mixture is equally effective as the strongest component
C.The combined activity is greater than the sum of individual activities
D.The chemicals react to form a solid precipitate
Correct Answer: The combined activity is greater than the sum of individual activities
Explanation:Synergism occurs when two chemicals applied together produce a level of control superior to the sum of their individual effects.
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50A fungicide dosage is given as 2 kg/ha. If you are using a knapsack sprayer that applies 500 Liters of water per hectare, what is the concentration of the spray fluid?