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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)
- Find the odd one.
- Puccinia graminis b. Fusarium oxysporum
- Cercospora personata d. Colletotrichum falcatum
- Whip tail disease of cauliflower is due to deficiency of ——
- Copper b. Zinc c. Molybdenum d. Iron
- Soft rot of vegetables is caused by
- Pythium spp b. Phytophthora spp
- Rhizoctonia spp. d. Colletotrichum sp.
- Characteristics of Xanthomonas campestris are
- Gram— , rod, non spore forming b. Gram+, rod, non spore forming
- Gram— , cocci, non spore forming d. Gram+, rod, spore forming
- δ- Endotoxins are produced by
- Bacillus thuringiensis b. Trichoderma viridae
- Xanthomonas oryzae d. Mycoplasma spp.
II State whether the following statements are true or false. (5 x 1 = 5)
- Tyloses are extensions of xylem vessels.
- Irish famine was due to Phytophthora infestans.
- Horizontal resistance is controlled by polygens.
- Cuscuta spp belongs to the family Convolvulaceae.
- Red rot of sugar cane is caused by Fusarium oxysporum.
III Complete the following. (5 x 1 = 5)
- Bordeaux mixture was discovered by ————-.
- Mosaic and motling type of symptoms are produced by ———–.
- Little leaf of brinjal is caused by ————–.
- Two or more disease cycles in a crop plant is termed as ———– disease.
- Macro and micro conidia are characteristic of ————– pathogen.
IV Answer the following each within 50 words. (5 x 1 = 5)
- Enumerate Koch postulates
- What are phytoalexins?
- What is Rogueing?
- Give the importance of Melodogyne spp.
- 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)
- Briefly explain the causes of epiphytotics.
- Explain physiological diseases.
- Write short notes on hypertrophy and hypotrophy.
- Give an account on chemicals that controls crop diseases.
- Illustrate and explain various types of spores produced by Puccinia spp.
- Describe the types of galls produced in plants.
- Discuss about the pathogens and symptoms of damping off.
- Comment on the disease little leaf of brinjal.
Part – C
Answer the following, each not exceeding 1500 words. (2 x 20 = 40)
- (a) Describe the various events occurs during the pathogenesis.
Or
(b) Explain the defense mechanisms mediated by biomolecules.
- (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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