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Plant Diseases

Description: GATE
Number of Questions: 15
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Tags: GATE Nature and Classification of Plant Diseases Plant Diseases Diseases
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Which one of the following fungal diseases of plantation crops is associated with Cercosporidium longipes?

  1. Yellow leaf spot of sugarcane

  2. Grey leaf spot of coconut

  3. Stem canker of sugarcane

  4. Red rot of sugarcane

  5. Brown leaf spot of sugarcane


Correct Option: E
Explanation:

Brown leaf spot of sugarcane is caused by Cercosporidium longipes.

Which of the following statement(s) is/are false regarding ‘African daisy plant’?

  1. Downy mildew disease is caused by Cercospora gerberae.
  2. Nectria canker disease is caused by Erysiphe cichoracearum.
  3. Sclerotium rolfsii causes ‘Southern blight’ disease.
  1. Only 1

  2. Only 2

  3. Only 3

  4. 1 and 2

  5. 2 and 3


Correct Option: D
Explanation:

Downy mildew disease of African daisy plant is caused by fungus- Plasmopara majewskii. Cercospora gerberae causes Cercospora leaf spot disease in African daisy plant. Nectria canker disease is caused by Haematonectria haematococca fungus in African daisy plant. Powdery mildew is caused by the fungal pathogen Erysiphe cichoracearum in African daisy plant. Southern blight disease is caused by Sclerotium rolfsii in African daisy plant. Hence, 1 and 2 are false statements.

The fungus(fungi) responsible for ‘bird’s eye rot’ in grapes is/are A. Mycosphaerella angulata B. Elsinoe ampelina C. Sphaceloma ampelinum

  1. Only A

  2. Only B

  3. Only C

  4. A and B

  5. B and C


Correct Option: E
Explanation:

The causing fungal pathogens responsible for bird’s eye rot are Elsinoe ampelina and Sphaceloma ampelinum.
Angular leaf spot of grapes is caused by the fungus Mycosphaerella angulata. Hence, the correct answer is Elsinoe ampelina and Sphaceloma ampelinum.

Which of the following statements is/are not true?

  1. Leaf streak disease of maize is caused by Stenocarpella macrospora
  2. Stem rot of potato is caused by Sclerotium rolfsii.
  3. Athelia arachnoidea causes crater rot in carot.
  4. Cercospora brachypus causes noble rot disease in grapes.
  1. Only 1

  2. 1 and 2

  3. 2 and 3

  4. 3 and 4

  5. Only 4


Correct Option: E
Explanation:

1) Leaf streak disease is caused by the fungus Stenocarpella macrospora in maize. 2) The causing fungal pathogen for stem rot of paotato is Sclerotium rolfsii. 3) Athelia arachnoidea causes crater rot in carot. 4) Grey rot or noble rot disease is caused by Botrytis cinerea in grapes. Mycosphaerella angulata and Cercospora brachypus cause angular leaf spot in grapes. Hence, only statement 4 is false.

Match the almond diseases in List-A with causing fungal pathogens in List-B ||| |---|---| |List-A |List-B| |A. Armillaria root rot|1. Venturia carpophila| |B. Green fruit rot|2. Rhizomorpha subcorticalis| |C. Hull rot|3. Rhizopus sp| |D. Scab|4. Botrytis cinerea|

  1. A - 2, B - 4, C - 3, D - 1

  2. A - 3, B - 1, C - 4, D - 2

  3. A - 2, B - 4, C - 1, D - 3

  4. A - 1, B - 3, C - 2, D - 4

  5. A - 2, B - 1, C - 3, D - 4


Correct Option: A
Explanation:

Armillaria root rot is caused by the fungi- Armillaria mellea and Rhizomorpha subcorticalis in almond. Green fruit rot disease of almond is caused by Botrytis cinerea, Botryotinia fuckeliana and Monilinia fructicola. Hull rot disease of almond is mainly caused by Rhizopus sp. Venturia carpophila and Cladosporium carpophilum cause Scab disease of almond. Hence, the sequence of codes A - 2, B - 4, C - 3, D - 1 is correct.

‘Wart’ disease of potato is caused by _________________________.

  1. Polyscytalum pustulans

  2. Synchytrium endobioticum

  3. Sclerotinia sclerotiorum

  4. Phytophthora infestans

  5. Erysiphe cichoracearum


Correct Option: B
Explanation:

The causative agent for wart disease of potato is Synchytrium endobioticum.

Which among the following statements is/are not true?

  1. The causing agent for areolate leaf spot in citrus is Nematospora coryli.
  2. Nectria canker disease is caused by Erysiphe cichoracearum.
  3. Glomerella cingulata causes bitter rot in peanut.
  1. Only 1

  2. Only 2

  3. Only 3

  4. 1 and 2

  5. 2 and 3


Correct Option: D
Explanation:
  1. The causative agents for areolate leaf spot in citrus are- Thanatephorus cucumeris, Pellicularia filamentosa and Rhizoctonia solani. Dry fruit rot is caused by Nematospora coryli in citrus.
    1. Nectria canker disease is caused by Haematonectria haematococca fungus in African daisy plant. Powdery mildew is caused by the fungal pathogen Erysiphe cichoracearum in African daisy plant.
    2. Bitter rot of peanut is caused by the fungal pathogen Glomerella cingulata. Hence, 1 and 2 both are false statements.

The fungus responsible for ‘loose smut’ of barley is/are: A. Ustilago tritici B. Ustilago segetum C. Pyrenophora wirreganensis

  1. Only A

  2. Only B

  3. Only C

  4. A and B

  5. B and C


Correct Option: A
Explanation:

Infected heads emerge as a mass of dark brown powdery spores is called loose smut. Fungus Ustilago tritici causes loose smut disease in barley. Covered smut is caused by the fungus Ustilago segetum var. hordei in which the heads that emerge are dark in colour and smut balls take the place of the grain. Wirrega blotch of leaf is caused by the fungus Pyrenophora wirreganensis.

Which one of the following rust diseases is caused by the fungus Gymnosporangium clavipes?

  1. Quince rust in apple

  2. Pacific Coast pear rust

  3. Japanese apple rust

  4. Cedar apple rust

  5. American hawthorne rust in apple


Correct Option: A
Explanation:

Gymnosporangium clavipes causes quince rust in apple.

Match the diseases of fruit crops in column-I with fungal pathogens in column-II. ||| |---|---| |Column- I |Column-II| |A. Leaf spot of cherries and palms|1. Cerecosoridium viticola| |B. Brown leaf spot of grapes|2. Taphrina deformans| |C. Citrus greasy leaf spot|3. Blueriella sp.| |D. Leaf curl of peach and apricot|4. Mycosphaerella musicosa| | |5. Mycosphaerella citri|

  1. A - 3, B - 1, C - 5, D - 2

  2. A - 5, B - 1, C - 4, D - 2

  3. A - 3, B - 4, C - 5, D - 2

  4. A - 2, B - 3, C - 4, D - 1

  5. A - 1, B - 4, C - 5, D - 3


Correct Option: A
Explanation:

Leaf spot of cherries and palms is caused by Blueriella sp. Brown leaf spot of grapes is caused by Cerecosoridium viticola. Citrus greasy leaf spot is caused by the fungus Mycosphaerella citri. Banana leaf spot is caused by Mycosphaerella musicosa. Taphrina deformans causes leaf curl of peach and apricot. Hence, the correct sequence of codes is A - 3, B - 1, C - 5, D - 2.

The causing agent for angular leaf scorch of grapes is _______________________.

  1. Mycosphaerella angulata

  2. Armillaria mellea

  3. Pseudopezicula tetraspora

  4. Sphaceloma ampelinum

  5. Botrytis cinerea


Correct Option: C
Explanation:

Pseudopezicula tetraspora is a fungus and causes angular leaf scorch in grapes.

Select the correct match Column-I and Column-II ||| |---|---| |Column-I |Column-II| |A. Angular leaf scorch of grapes|1. Leptosphaeria sacchari| |B. Ring spot of sugarcane|2. Phymatotrichopsis omnivore| |C. Collar canker of tea|3. Pseudopezicula tetraspora| |D. Cotton root rot of crucifer|4. Phomopsis theae|

  1. A - 1, B - 3, C - 4, D - 2

  2. A - 2, B - 3, C - 4, D - 1

  3. A - 3, B - 4, C - 1, D - 2

  4. A - 3, B - 1, C - 4, D - 2

  5. A - 4, B - 3, C - 1, D - 1


Correct Option: D
Explanation:

Pseudopezicula tetraspora is a fungus and causes angular leaf scorch in grapes. The causing fungus for ring spot in sugarcane is Leptosphaeria sacchari. Collar canker of tea is caused by Phomopsis theae. Cotton root rot of crucifer is caused by the fungus Phymatotrichopsis omnivore. Hence, the correct answer using the codes is A - 3, B - 1, C - 4, D - 2.

Which of the following statements is/are not true about fungal diseases of coffee?

  1. Red blister disease of coffee is caused by Fusarium solani.
  2. Phoma costaricensis causes thread blight disease.
  3. Gibberella xylarioides causes tracheomycosis.
  1. Only 1

  2. Only 2

  3. Only 3

  4. 1 and 2

  5. 2 and 3


Correct Option: D
Explanation:

Red blister disease of coffee is caused by Cercospora coffeicola. Dry root rot disease of coffee is caused by Fusarium solani. Thread blight disease is caused by Corticium koleroga in coffee. Phoma costaricensis causes tip blast disease in coffee. Tracheomycosis is caused by the fungus Gibberella xylarioides in coffee.

Match the diseases in List-A with causing fungal pathogens in List-B and select the correct answer using the codes given below ||| |---|---| |List-A |List-B| |A. Cottony snow mold of wheat|1. Sclerotium rolfsii| |B. White leaf spot of crucifer|2. Coprinus psychromorbidus| |C. Hull rot of almond|3. Rhizopus sp.| |D. Southern blight of cotton|4. Pseudocercosporella capsellae|

  1. A - 2, B - 4, C - 3, D - 1

  2. A - 3, B - 1, C - 4, D - 2

  3. A - 2, B - 4, C - 1, D - 3

  4. A - 1, B - 3, C - 2, D - 4

  5. A - 2, B - 1, C - 3, D - 4


Correct Option: A
Explanation:

Cottony snow mold of wheat is caused by the fungus Coprinus psychromorbidus. White leaf spot of crucifer is caused by Pseudocercosporella capsellae. Hull rot disease of almond is mainly caused by Rhizopus sp. Southern blight of cotton is caused by the fungal pathogen Sclerotium rolfsii. Hence, the sequence of codes A - 2, B - 4, C - 3, D - 1 is correct.

Which of the following fungicides are used to control fungal diseases in apple? A. Methoxychlor B. Malathion C. Fenarimol D. Thiram E. Triadimefon

  1. A and B

  2. B and C

  3. A, B and D

  4. B, D and E

  5. A, B C, D and E


Correct Option: E
Explanation:

A general purpose tree fruit spray, available under a variety of trade names, is effective for control of many of the common diseases and insect pests of apple. This mixture usually contains captan as the fungicide component and methoxychlor and malathion or carbaryl as the insecticide component. Other alternative to control of fungal diseases are-

  1. coppers (fixed)- early season control of scab and fire blight;
  2. fenarimol- control of scab, mildew, and rust;
  3. ferbam- some control of scab, rust, black rot, and the summer diseases; causes undesirable black residue when used late in season;
  4. maneb, mancozeb- control of rust, scab, fruit rots, and summer diseases;
  5. myclobutanil- control of scab, powdery mildew and cedar-apple rust;
  6. sulfur- for control of mildew; some control of scab, summer diseases, and fruit rots; can be phytotoxic to some cultivars and may cause fruit russetting and/or yield reduction when sprayed after bloom;
  7. thiram- some control of scab, rust, and summer diseases;
  8. thiophanate-methyl- control of scab, fruit rots, and summer diseases;
  9. triadimefon- very good control of powdery mildew and rust.
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