The Vision into the Plant Pathology

Thursday, 7 January 2021

Multiple choice questions

1. Father of plant pathology

a) Anton de Bary b) Micheli

c) Clusius d) Prometheus

2. Father and founder of mycology

a) P.A. Michelli b) P.A. Saccardo c) Clusius d) Butler

3. Father of plant pathology and mycology in India

a) Anton de Bary b) Persoon c) E.J. Butler d) Patel

4. Father of forest plant pathology

a) H.M Ward b) Robert Hartig c) Homer d) P.A. Micheli

5. Father of tropical plant pathology – H M Ward

a) Theophrastus b) Robert Hartig c) H.M Ward d) Butler

6. When we celebrate robigolia every year

a) January 25 b) February 25 c) March 25 d) April 25

7. Who observed the teliospores of Phragmidium mucronatum for the 1^st time in microscope a) a) Ward b) Burgaff c) Robert Hook d) Angus

8. In ancient Rome an annual festival was held for blessing of the Rust God named

a) Robigus b) Angus

c) Robusta d) None of the above

9. Late blight of potato caused famine in Ireland in the year

a) 1872 b) 1857 c) 1845 d) 1945

10. Who discovered the existence of bacteria

a) Anton von Leeuwenhoek b) Louis Pasteur

c) J.F. Dastur d) Robert Koch

11. Irish famine was due to

a) Bipolaris oryzae b) Phytophthora infestans

c) Puccinia graminis d) Amanita verna

12. Which pathogen caused heavy losses to wine industry in France due to its epidemic in 1875

13. a) Phytophthora infestans b) Plasmopara viticola

14. c) Helminthosporium oryzae d) Uncinula nicator

15. Bordeaux mixture was developed by

a) Millardet b) Michelli

C) Bowley d) Anton de Bary

16. Citrus greening is cause by

a) Xanthomonas axonopods

b) Candidatus liberibacter asiaticus

c) Xanthomonas compestris

d) None

17. Ergot is obtained from

a) Synchytrium endobioticum

b) Pythium aphanidermatum

c) Claviceps purpurea

d) Cryphonectria parasitica

18. Fire blight of apples was 1^st reported by

a) Anton de Bary b) Adolf mayer

c) E.F. Smith d) T.J. Burril

19. Wheat loose smut is a

a) Internally seed borne pathogen b) Externally seed borne pathogen

c) Both d) None

20. Flagella all over the body

a) Xylella b) Xanthomonas

c) Erwinia d) Pseudomonas

21. Which fungicide used against downy mildew

a) Metalaxyl b) Karathane

c) Oxathin d) Streptomycin

22. Race specific resistance

a) Vertical resistance b) Horizantal resistance

c) Adult plant resistance d) Apparent resistance

23. Hypertrophy

a) Cell death b) Cell enlargement

c) Increase in number of cells d) Decreased in cell divisions

24. Hyperplasia

a) Cell death b) Cell enlargement

c) Increased cell divisions d) Decreased in cell divisions

25. Dictyospore is having

a) Vertical septa b) Horizantal septa

c) Both vertical and horizantal septa d) None

26. Pleomorphic character is found in

a) Fungi b) Bacteria c) Virus d) None

27. Bacteriophage is a

a) Virus infecting bacteria b) Virus infecting eukaryotes

c) Nacked ssRNA particles d) animal viruses

28. Ti plasmid present in

a) Agrobacterium radiobacter b) Agrobacterium tumefaciens

c) Xanthomonas axonopodis d) Pseudomonas solanacearumm

29. Which bacteria produce yellow pigment on growth media

a) Xanthomonas b) Pseudomoans

c) Agrobacterium d) Rhizobium

30. Which of the following is a gram positive bacteria

a) Bacillus b) Xanthomonas

c) Erwinia d) Pseudomonas

31. Microscope discovered by

a) Needham b) Spallanzini

c) Koch d) Zacharias Janssen

32. Exclusion of plant disease by legislation is known as

a) Disease resistance b) Plant quarantine

c) Biological control of plant d) Cultural control

33. First plant parasitic nematode was reported

a) Meloidogyne b) Heterodera

c) Anguina d) Globodera

34. Flag smut of wheat is caused by

a) Ustilago tritici b) Urocystis tritici

c) Ustilago hordei d) Taphrina deformans

35. Pasteurization temperature

a) 65^oC b) 62.8^oC c) 100^oC d) 150^oC

36. Mycoplasma disease of plant was first reported by

a) Butler b) Brefeld c) Anton de Bary d) Doi et al

37. Nematodes are also known as

a) Tapeworms b) Trematodes c) Earthworms d) Round worms

38. Bacterium cell wall is made of

a) Peptidoglycan b) Protein c) Chitin d) Cellulose

39. Alexander Fleming (1928) discovered

a) Penicillin b) Strptomycin c) Tetracycline d) Griseofulvin

40. Bacilli are

a) Rod shaped b) Sprial c) Spherical d None

41. Bengal famine is due to

a) Helminthosporium oryzae b) Bipolaris oryzae

c) Pyricularia oryzae d) A and B

42. Rice Khaira disease is due to

a) Zinc deficiency b) Mo deficiency

c) Copper deficiency d) Boron deficiency

43. Wheat stem rust is caused by

a) Puccina graminis tritici b) P. recondita

c) P. striiformis d) Ustilago hordei

44. Rice blast is due to

a) Pyricularia b) Xanthomonas

c) Cercospora d) Erysiphe

45. Botulism is due to

a) Bacillus b) Pseudomonas

c) Agrobacterim d) Clostridium

46. Powdery mildew fungi belong to the family

a) Erysiphaceae b) Hypocereaceae

c) Hypomycetaceae d) Nectriaceae

47. Red rot of sugarcane is caused by

a) Fusarium b) Alternaria

c) Dreschlera d) Colletotrichum

48. Rust is effectively controlled by

a) Carboxin b) Oxycarboxin c) Carbendazim d) Metalaxyl

49. Smut can be effectively controlled by

a) Carboxin b) Oxycarboxin c) Carbendazim d) Metalaxyl

50. Taphrina causes the disease

a) Chilli leaf curl b) Tomato leaf curl

c) Peach leaf curl d) Potato leaf curl

1. Life cycle of wheat stem rust – Puccinia graminis tritici

Domain – Eukarya

Kingdom – Fungi

Phylum – Pucciniomycota

Sub phylum - Pucciniomycotinia

Class – Puccniomycetes

Order – Pucciniales

Family – Pucciniaceae

Genus – Puccinia

Species – graminis

Stage	spores	Colour	Appearance
O	Pycniospores	Hyaline	Upper
I	Aeciospores	Yellow	Lower
II	Uredospores	Golden brown	Primary host
III	Teliospores	Black	Primary host
IV	Basidiospores	Hyaline	Soil debris

Symptoms – Red colour rust pustules appears in stem and leaves. Alternate host is Barberry

Life cycle – When wheat crop attains maturity the uredinia appears on rut pustules and developed as urediniospores, these are single celled, which contains enormous amount of food reserves for long distance dissemination, at the end of the wheat season it starts to produce less urediniospores and more teiospores.

Telia are black, elongated, bi-celled, dark brown in colour, it is a resting spore which represents sexual apparatus of the fungus in which karyogamy ad meiosis takes place, when favourable conditions occurs its germinate and produce basidispores of opposite mating types

Basidiospores infect barberry but not wheat, several basidiospores produce flask shaped pycnium. Several pycnia of opposite mating types are generally formed in the same leaf. On the corresponding to the lower surface it produce aecia

Aeciospores it contains reserve food material, the aeciopsores can’t germinate on berberry and germinate on wheat leaf.

Types of teliospores –

Types of teliospore	Example
Single celled teliospore	Uromyces
Double celled teliospore	Puccinia
Multicelled teliopsore	Phragmidium
Durnip shaped uredospore	Hemileia
Kidney shaped teliospore	Hemileia
Crust like telispore	Melampsora
Parachute like teliospore	Ravenelia

Types of rust

Ø Autoecious rust – Completes its entire life cycle in a single host

Ø Heteroecious rust - Requires genetically two hosts to complete their life cycle

Ø Autoecious macrocyclic rust – Eg – B – Bean rust

F – Flax rust

S - Sunflower rust

S - Safflower rust

Ø Autoecious demicyclic rust – Eg – Rubus orange rust – Gymnoconia peckiana

Ø Heteroecious macrocyclic – Eg – Wheat stem rust – Puccinia graminis tritici

White pine blister blight – Cronartium rubicola

Ø Heteroecious demicyclic – Eg – Cedar apple rust – Gymnosporangium juniperi

Viriginianae

2. Sugarcane ratton stunting

Caused by - Leifsonia xyli subsp. xyli (old name – Clavibacter xyli subsp. xyli), aerobic bacterium.

Symptoms:

· The affected plants are stunted, the stunting being most severe in stubble and ratoon crops.

· In infected stocks, the presence of pin head like orange coloured dots of bacteria on the internal soft tissue in the nodal region

· The setts taken from diseased plants germinate poorly and the few shoots that are emerged grow very slowly.

Spread – Spread through infected setts

Management strategies

· Select healthy setts for planting.

· Field should maintain at proper sanitation.

· Treat the setts with hot water at 50°C for about 2 hours this gives 100 per cent control.

3. Tikka leaf spots of ground nuts

Tikka disease: Cercospora arachidicola (early tikkaleaf spot) & Cercospora personata (late tikka leaf spot)

Symptom:

Early tikka leaf spot: Seen within 3-4 weeks of sowing. On the leaves irregular to circular reddish brown/ black lesions surrounded by “yellow halo”
Late tikka leaf spot: seen within 5-7 weeks of sowing. Mostly on the leaf margin, enlarged black lesion without yellow halo.

Management:

Foliar spray with chlorothalonil -0.25%.

4. Diseases of mango

Malformation – Fusarium moniliforme var. subglutinans

· Symptoms – Vegetative malformation – Bunchy top symptom

· Floral malformation – produce huge number of flowers gives bushy appearance

· It is also known as “bunchy top”. Serious threat to mango growing tract of the world. Especially in North India Industries were being threatened. First report in 1891 by Maries from Darbhanga, Bihar. More percent trees are affected in North India.

· Management –

i. Diseased plants should be destroyed

ii. Use of disease free planting material

iii. Incidence reduced by spraying 100-200ppm NAA during October.

iv. Pruning of diseased parts along the basal 15-20 cm apparently healthy portions

v. This is followed by the spraying of Carbendazim (0.1%) or Captafol (0.2%).

Powdery mildew – Oidium mangiferae

· Symptoms – White powdery growth on leaves, Tender shoots, floral parts, Fruits.

ü Secondary spread by air borne conidia

ü Warm temperature with heavy morning dew and cloudy weather favour the disease development

ü 3-4 days 24- 30⁰C min. and max. temp. with 73-83% min. and max. RH.

· Management

ü Dusting the plants with fine sulphur (250-300 mesh) @0.5kg/tree or foliar spray with wettable sulphur (0.2%) or karathane/Tridemorph/Carbendazim/hexaconazole/difenconazole (0.1%) can be effectively reduce the incidence.

Anthracnose – Gloeosporium gloeosporioides

Symptoms – Leaf spot – Circular, Reddish brown spot on leaf surface

Die back – Dieing of twigs from tip to downwards

Floral blight – blackening of floral axis

Fruit – Irregular black lesion o fruit leads to rotting

DIE-BACK: Lasiodiplodia theobromae (Botryodiplodia theobromae)

Symptoms:

· The term “die back” implies death of a plant from top to downwards

· Symptoms can be seen at any time of year but most conspicuous during October and November

· Dying back of twigs from top down wards and drying of leaves particularly of old trees followed by complete defoliation which gives appearance of “Fire scorch”

· Management -

ü Systemic fungicide like Carbendazim, Thiophanate-methyl, Chlorothalonil, difenconazole, carboxamide are recommended generally, but the reality is very difficult to control the disease and save the tree

BACTERIAL CANKER : Xanthomoanas campestris pv. mangiferae indicae

Symptoms

· Small water- soaked lesions appear in groups on surface of leaves. Turn brown to black and get surrounded by yellow halo.

· Later lesions were often rough and raised. On fruits also same symptom and show cracks in the skin and drop premature. Water soaked spots which turn into cankers on fruits, leaves, petioles, twigs and branches. Hence, they renamed the disease as bacterial canker.

RED RUST: Cephaleuros virescens - Algae

· Symptoms : Rusty red pustules of the algae on surface of leaves, veins, petioles and young twigs. First spots are greenish gray – converts to reddish brown. Spots are circular to irregular in shape.

Other diseases in mango

Sooty mould – Capnodium ramosum
Grey blight – Pestalotiopsis mangiferae
Red rust – Cephaleuros virescens
Bacterial canker – Xanthomonas campestris pv. mangiferae-indica
Giant mistletoe – Dendropthe sp. (Loranthus)

Classification of powdery mildews

PHYLUM: Ascomycota

CLASS: Filamentous ascomycetes

ORDER: Ersiphales (the powdery mildew fungi) Asci in fruiting bodies completely closed (cleistothecia). Myceliun, conidia and cleistothecia on surface of plant. Obligate parasites.

The following are some of the main genera of powdery Mildews and some of the important diseases they cause.

GENUS:

· Blumeria; cereals and grasses

· Erysiphe; Herbaceous plants. Begonia, chrysanthemum, Cucurbits, dahlia, zinnia, legumes, beets, crucifers, tomato.

· Leveillula; Tomato Microsphaera; Azalea, rhododendron, lilac,

· Oidium; (anamorph only) tomato, begonia.

· Phyllactinia sp; Shade and forest trees.

· Podosphaera; Apple (P. leucotricha), quince, apricot, cherry, Peach, plum, cucurbits.

· Sphaerotheca; strawberry, gooseberry, currant, peach, rose.

· Uncinula; Grape (U. necator).

Types of powdery mildew

The powdery mildew fungi are characterised based on the type of mycelium and conidiogenesis, these are 3 types, Oidium, Oidiopsis, Ovulariopsis

Category	*Oidium*	*Oidiopsis*	*Ovlariopsis*
Mycelium	Hyaline, septate and ectophytic	Hyaline, septate and endophytic	Hyaline, septate, ecto and endophytic
Haustoria	Present in epidermis only	Present in epidermis and spongy cells only	Epidermal haustoria absent
Conidiophore	Short club shaped, non septate	Long branched and septate	Branched, septate
Conida	Cylindrical or barrel shaped in chains	Single celled, club shaped	Single celled, clavate or club shaped
Clestothecia	Myceliod appendages	Myceliod appendages	bulbous appendages
Host (species can produce this type)	Erysiphe	Leveillula	Phyllactinia