Session 2: Disease Management
Unit 6: Insect Pests, Diseases, and WeedManagement
Textual Question-Answers
Check Your Progress
Fill in the Blanks
1. An interaction between a susceptible host and a virulent pathogenin a favourable environment is known as………………
Ans: disease
2. An integrated approach used for avoiding and controlling thediseases is termed as………………
Ans: integrated disease management
3. Chemical or combination of chemicals found lethal to fungi andescapes the host from infection is called………………
Ans: fungicide
4. Affectivity of fungicide when translocated to the whole system ofthe plant, irrespective of the place of application, is called…………
Ans: systemic action
5. Affectivity of the fungicide when restricted to the area of applicationis called………………
Ans: contact action
6. The mechanism of controlling the growth of microorganismsthrough another microorganism is called………………
Ans: biological control
Multiple Choice Questions
1. Disease occurs only when there is………………
(a) virulent pathogen
(b) susceptible host
(c) favourable climate
(d) All of the above
Ans: (d) All of the above
2. Fungi which have antagonistic properties against many fungi are………………
(a) trichoderma harzianum
(b) trichoderma viride
(c) Both (a) and (b)
(d) None of the above
Ans: (c) Both (a) and (b)
3. Neem seed oil can be used effectively against………………
(a) anthracnose
(b) charcoal rot
(c) Both (a) and (b)
(d) None of the above
Ans: (c) Both (a) and (b)
Subjective Questions
1. Describe fungicides and their types.
Ans: Fungicides are chemical substances or mixtures of chemicals usedto kill or inhibit the growth of fungi that cause plant diseases. They protect crops from fungal infection and help in improving crop yield and quality. Fungicides are mainly of two types: contact fungicides and systemicfungicides. Contact fungicides remain on the surface of the plant and prevent infection at the point of application. Systemic fungicides are absorbed by theplant and translocated to different parts, protecting the entire plant from fungal
attack.
2. Describe different methods of fungicidal application.
Ans: Fungicides can be applied by different methods depending on thecrop and nature of disease. Seed treatment is done to protect seeds andseedlings from soil and seed-borne diseases. Soil application is used to control soil-borne pathogens by mixing fungicides with soil. Foliar spray involvesspraying fungicides on leaves and stems to control aerial diseases. Seedlingdip treatment is done before transplanting to protect seedlings from infection.
3. Describe different cultural methods of disease control.
Ans: Cultural methods are practices adopted to reduce disease incidencewithout using chemicals. These include the use of disease-free and resistant varieties, crop rotation to break the life cycle of pathogens, proper spacing forgood aeration, timely sowing, removal and destruction of diseased plant parts, deep ploughing, and proper irrigation and drainage management.
4. Describe bio-control of disease and antagonism.
Ans: Bio-control of disease is the method of controlling plant pathogensusing living microorganisms. These beneficial organisms suppress diseasecausing pathogens through competition, parasitism, or production of toxic substances. Antagonism refers to the harmful effect of one microorganism onanother. Trichoderma species are commonly used antagonists against manysoil-borne fungal pathogens.
Match the columns
A
1. Powdery mildew
2. Bio-control
3. Cultural method
4. Nematode
5. Rust
B
(a) Use of resistant varieties
(b) Sign of gall in roots
(c) Bright orange pustules appear on leaves
(d) Trichoderma spp.
(e) White fungal growth on leaves
Ans:
1 – (e)
2 – (d)
3 – (a)
4 – (b)
5 – (c)
