Diseases and Treatment: VII. Main Plant Diseases

Total Questions: 20

1. Which of the following statements is/are correct? [I.A.S. (Pre) 2016]

Viruses can infect

Bacteria
Fungi
Plants

Select the correct answer using the code given below:

(a) 1 and 2 only
(b) 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Correct Answer: (d) 1, 2 and 3

Solution:A virus is a small infectious agent that replicates only inside the living cells of other organisms. It can infect all types of life forms, from animals and plants to microorganisms, including bacteria and fungi.

2. Match List-I with List-II and select the correct answer from the code given below the lists. [U.P. P.C.S. (Pre) 2022]

List-I (Plant Disease)	List-II (Cause)
A. Citrus Canker	1. Insect
B. Red rot disease of sugarcane	2. Deficiency of oxygen
C. Khaira disease of rice	3. Bacteria
D. Salna disease of wheat	4. Fungus

Code

	A	B	C	D
(a)	3	4	2	1
(b)	2	3	1	4
(c)	4	1	2	3
(d)	3	1	4	2

Correct Answer: (a)

Solution:Citrus canker is a disease affecting Citrus species caused by the bacterium Xanthomonas (X.axonopodis; X.campestris). Infection causes lesions on the leaves, stems, and fruit of citrus trees, including lime, oranges, and grapefruit. This disease significantly affects the vitality of citrus trees, causing leaves and fruit to drop prematurely. Red rot disease of sugarcane is characterized by interrupted red and white patches within the cane along with a sour alcoholic odour when the cane is split open. Caused by the fungus Colletotrichum falcatum (Glomerella tucumanensis), red rot first attracts attention by a yellowing and withering of the leaf, and eventually the entire plant dies. Black heart (Krishnakant) disease of potatoes occurs primarily in storage when the tubers do not receive enough oxygen. Blackening of the tuber centre follows acute oxygen deficiency associated with either low temperature in confined storage or high field soil temperatures. The tissue dies from the inside out and turns jet black. The ear cockle disease of wheat occurs in most wheat- growing parts of the world. In India, the disease commonly occurs in U.P., Punjab and Western part of Bihar, and is popularly known as 'sehun' disease. Nematodes are the causal organism of ear cockle disease. It is not caused by the insects.

Note: 'Sahu' disease of wheat is given in the question, which should be 'sehun'.

3. Which one of the following in not correctly matched? [U.P.P.C.S. (Mains) 2009]

(a) Wheat - Phalaris minor
(b) Potato - Late blight
(c) Bajra - Ergot
(d) Sugarcane - Powdery mildew

Correct Answer: (d) Sugarcane - Powdery mildew

Solution:Powdery mildew is related with wheat, grape, barley, onion, apple and pea etc. not with sugarcane.

Phalaris minor, commonly known as little canary grass, is a common weed that can be found in wheat fields.

While late blight is a serious fungal disease affecting potato plants, it is caused by the oomycete pathogen Phytophthora infestans.

Ergot is a fungal disease that affects several cereal crops, including bajra (pearl millet). It is caused by the fungus Claviceps fusiformis.

4. Which one of the following is not correctly matched? [U.P.P.C.S. (Mains) 2017]

(a) Paddy - Wilt
(b) Mustard - White rust
(c) Bajra - Smut
(d) Groundnut - Tikka

Correct Answer: (a) Paddy - Wilt

Solution:Wilt affects gram, chickpea, and sugarcane, not paddy. Other pairs are correct.

Tikka disease is indeed a disease of groundnut, it's more specifically known as Tikka disease of groundnut.

Mustard plants are susceptible to white rust, a fungal disease.

Smut is a common disease of bajra (pearl millet).

5. Which element deficiency causes chlorosis in maize plant? [U.P. U.D.A./L.D.A. (Pre) 2006]

Crop	Disease
(a) Paddy	Wilt
(b) Mustard	White rust
(c) Bajra	Smut
(d) Groundnut	Tikka

Correct Answer: (a)

Solution:Wilt affects gram, chickpea, and sugarcane, not paddy Tikka disease is indeed a disease of groundnut, it's more specifically known as Tikka disease of groundnut. Mustard plants are susceptible to white rust, a fungal disease. Smut is a common disease of bajra (pearl millet).

6. Which element deficiency causes chlorosis in maize plant? [U.P. U.D.A./L.D.A. (Pre) 2006]

(a) Nitrogen
(b) Zinc
(c) Copper
(d) Manganese

Correct Answer: (b) Zinc

Solution:'Zn' (Zinc) is a micronutrient element which is required in little quantity by plants. Due to deficiency of Zn, chlorosis occurs in maize plants in which leaves of plants are undeveloped and plants become dwarf. The tip of maize leaves get white and they are mottled and yellow because of Zn deficiency.

7. White tip of maize leaves indicates the deficiency of [U.P.P.C.S. (Mains) 2010]

(a) Fe
(b) Mn
(c) N
(d) Zn

Correct Answer: (d) Zn

8. White Bud disease in plant is caused by deficiency of [Jharkhand P.C.S. (Pre) 2016]

(a) Zinc
(b) Copper
(c) Boron
(d) Manganese

Correct Answer: (a) Zinc

Solution:Zinc (Zn) deficiency includes khaira disease of rice, white bud of maize, mottle leaf (little leaf) or frenching of citrus and cotton. These symptoms often appear first in newer, upper leaves as zinc is an immobile nutrient. Zinc is crucial for plant health, impacting enzyme activation, protein synthesis, and hormone regulation.

Applying zinc fertilizers (e.g., zinc sulfate, zinc oxide) can correct the deficiency. Spraying plants with zinc solutions can provide a quick fix. Treating seeds with zinc before planting can help ensure sufficient zinc for early growth. Dipping seedlings in zinc solutions can also provide early zinc nutrition. Improving soil health through organic matter additions and proper drainage can enhance zinc availability.

9. Pyrilla is a pest of which crop? [M.P. P.C.S. (Pre) 1990]

(a) Wheat
(b) Rice
(c) Sugarcane
(d) Soyabean

Correct Answer: (c) Sugarcane

Solution:Pyrilla is a leafhopper that sucks the sap from leaves of sugarcane, causing yellow patches and drying of leaves, which severely affects sugarcane growth.

10. The deadly disease of groundnut is: [Jharkhand P.C.S. (Pre) 2021]

(a) Powdery mildew
(b) None of these
(c) Tikka
(d) Damping off

Correct Answer: (c) Tikka

Solution:Tikka disease is a fungal disease that primarily affects groundnut crops. It is caused by the pathogen Alternaria arachidis and is characterized by the development of small, dark lesions on various parts of the plant, particularly the leaves and pods. Tikka disease can lead to reduced crop yield and quality, making its management crucial for groundnut farmers.

The most noticeable symptom of Tikka disease is the presence of small, circular irregularly shaped lesions on the leaves. These lesions start as dark spots and may have a concentric ring pattern, resembling a target or "tikka." In addition to leaves, Tikka disease can also affect stems and pods, causing similar lesions. Stem lesions may lead to wilting or lodging of plants. In humid conditions, the lesions may produce dark, powdery spores, giving the affected areas a dusty appearance. Severe Tikka disease infections can result in reduced groundnut yield and quality, affecting both the number of pods and the size of individual nuts.

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