IB 25

LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

B.Sc. DEGREE EXAMINATION – PLANT BIO. & BIO TECH.

SIXTH SEMESTER – APRIL 2007

PB 6604/PB 5501 –  PLANT DISEASES & MANAGEMENT

 

 

 

Date & Time : 16.04.2007/9.00-12.00      Dept. No.                                                      Max. : 100 Marks

 

 

 

Part – A (20 marks)

 

Answer all the questions.

I  Choose the best answer                                                                                           (5 x 1 = 5)

 

1. Find the odd one.

1. Puccinia graminis b. Fusarium oxysporum
2. Cercospora personata d. Colletotrichum falcatum

 

1. Whip tail disease of cauliflower is due to deficiency of ——

1. Copper b. Zinc c. Molybdenum           d. Iron

 

1. Soft rot of vegetables is caused by

1. Pythium spp b. Phytophthora spp
2. Rhizoctonia spp. d. Colletotrichum sp.

 

1. Characteristics of Xanthomonas campestris are

1. Gram^— , rod, non spore forming b. Gram⁺, rod, non spore forming
2. Gram^— , cocci, non spore forming d. Gram⁺, rod, spore forming

 

1. δ- Endotoxins are produced by

1. Bacillus thuringiensis b. Trichoderma viridae
2. Xanthomonas oryzae d. Mycoplasma spp.

 

II  State whether the following statements are true or false.                                      (5 x 1 = 5)

 

1. Tyloses are extensions of xylem vessels.
2. Irish famine was due to Phytophthora infestans.
3. Horizontal resistance is controlled by polygens.
4. Cuscuta spp belongs to the family Convolvulaceae.
5. Red rot of sugar cane is caused by Fusarium oxysporum.

 

III  Complete the following.                                                                                         (5 x 1 = 5)

 

1. Bordeaux mixture was discovered by ————-.
2. Mosaic and motling type of symptoms are produced by ———–.
3. Little leaf of brinjal is caused by ————–.
4. Two or more disease cycles in a crop plant is termed as ———– disease.
5. Macro and micro conidia are characteristic of ————–  pathogen.

 

 

 

 

 

IV Answer the following each within 50 words.                                                         (5 x 1 = 5)

 

1. Enumerate Koch postulates
2. What are phytoalexins?
3. What is Rogueing?
4. Give the importance of Melodogyne spp.
5. TMV. Expand and what type of nucleic acid present in it?

 

Part – B

 

Answer any FIVE of the following, each not exceeding 350 words.                                    (5 x 8 = 40)

 

1. Briefly explain the causes of epiphytotics.
2. Explain physiological diseases.
3. Write short notes on hypertrophy and hypotrophy.
4. Give an account on chemicals that controls crop diseases.
5. Illustrate and explain various types of spores produced by Puccinia spp.
6. Describe the types of galls produced in plants.
7. Discuss about the pathogens and symptoms of damping off.
8. Comment on the disease little leaf of brinjal.

 

Part – C

 

Answer the following, each not exceeding 1500 words.                                         (2 x 20 = 40)

 

1. (a) Describe the various events occurs during the pathogenesis.

Or

(b) Explain the defense mechanisms mediated by biomolecules.

 

1. (a) Write notes on the pathogens, symptoms, disease cycle and control measures

of Tikka disease of ground nut.

Or

(b) Give a detailed account of the disease downey mildew.

 

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