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Crop Protection 152 > Late blight > Flashcards

Late blight Flashcards

1
Q

What was the Irish potato famine and what was the dates?

A

It was a period of starvation and disease in Ireland from 1845 to 1850

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2
Q

What did all great civilizations have?

A

-Fixed places to live
-Staple food cultivated plant

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3
Q

What is an example of a staple food?

A

Potatoes
* Protein, carbohydrates and
vitamins

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4
Q

What are two things that should be known about the introduction of plant pathegens into a region?

A
  • Plant pathogen centre of origin -co-evolve with host plant species
  • Pathogen migrate (“travel”) with host plant, but not always
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5
Q

Where do potatoes come from?

A

From the Inca civilization in the Mountains Andean valleys

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6
Q

Where do P. infestans (in italics) come from ?
(Phytophthora infestans)

A

Andes or Mexico

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7
Q

How was potatoes accidentally introduced in Europe

A

Spanish galleons used raw or dried tubers as provisions (Stock) long voyages back home
* Not known how tubers survived hot and slow journey

Many separate small plantings made 1570 onwards
* Spain, France and Italy and then rest of Europe

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8
Q

Why was potatoes not accepted in Europe by peasants (a member of a class of persons, as in Europe, Asia, and Latin America, who are small farmers or farm laborers of low social rank) as a food source?

A
  • Superstition
    -Tubers aphrodisiac
  • “and eating of these roots doth excite Venus and increase the lust”
  • Resistance against new foods
  • Bitter green berries indicated plant useless
  • Poisonous plant since related to nightshade
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9
Q

What remaied Europes staple foods for many years when they did not accept potatoes in 1590?

A

Rey bread and oatmeal

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10
Q

What are the 4 reasons for Potato becoming a Staple Food
in Ireland

A
  • Rust and smut diseases grains and increasing Irish
    population
    -search more reliable staple foods
  • Irish population size increased 4 million to 8 million
    from 1800 to 1845
  • Irish suffered in 18th century from high rents requested
    English landlords
  • English soldiers often invaded Irish farmsteads, burnt
    grain and took pig
    -Each family had one pig
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11
Q

When did potatoes become a staple food in Irish and why?

A

1800’s
Yielded tons of potatoes compared to small tons grain seed

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12
Q

Potatoes was a hidden food source. how did they store/plant it and why?

A

–Stored and planted in “lazybeds”
* Long narrow soil beds 0.5 to 1m high, 2 to 3m wide and 30 m long

  • Made in bogs (wet soil areas) where soldiers didn’t bother to look
  • Often only source of foo
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13
Q

The destruction of potato crops in Ireland. When was this, what happend and whar were the reasons?

A
  • 1845
    -Potato plants all over europe destroyed and rotten tubers
    -Reasons:
  • Weather
  • Disease
  • Weak potatoes
  • God’s punishment
  • The Devil’s handiwork
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14
Q

What did Dr. Berkley in England notice? WHat was he then convinced of?

A

-Noticed fungal growth on diseased potato plant leaves
-Convinced cause of death of potato plants

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15
Q

What did this observations confirm?

A

Observations confirmed investigations by Dr. Montagne in Paris

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16
Q

Where were the findings published of the fungal growth? Did readers believe it?

A

Findings published in “Graderners’ Chronicle” but readers did not believe it
* Fungus was seen as scavenger and saprophyte (lives of dead
tissue), i.e. result to cause decaying potato plants

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17
Q

Arguments regarding cause death potato crops continued
until ?

A

1861

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18
Q

Explain what Anton De Bary( from Germany) did to prve P. infestans

A
  • Took two wo groups of healthy potato plants subjected same climatic conditions (cold and humid)
  • One group dusted P. infestans spores
  • Other group not dusted with spores
  • Spore dusted plant became sick and died
  • Plants not dusted spores remained healthy
  • Acceptance germ theory 1870s
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19
Q

What did de BAry name the fungal-like microbe?

A

Phytophthora infestans
* The terrible plant destroyer

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20
Q

What was the disease named caused by P. infestans and why?

A

Late blight, cause disease appears in late summer in europe

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21
Q

What were De Bary’s Findings on P.infestans?

A
  • P. infestans produces egg shaped spores very short disease cycle
    – Period lesion appearance and spore
    production on leaf only 5 days
    – One sporulating lesion produces
    300,000 spores/day
    –Spores named sporangia, which contain
    swimming zoospores
  • Tremendous number spores
    produced that quickly spread by wind
  • Pathogen spores also washed down from foliage to tubers causing tuber rot
22
Q

What are the foliar symptoms of late blight on potatoes?

A

The foliar symptoms of late blight on potatoes are:

Water-soaked spots on the leaves, usually light to dark green or yellow in color

Brown or black lesions on the lower leaves, often near the leaf tips or edges

White or gray fuzzy growth on the leaf underside, which is the spore production of the fungus

23
Q

What is a tuber?

A

a much thickened underground part of a stem or rhizome

24
Q

What are some symptoms of late blight on potato tuber?

A

Slightly sunken, brown to purplish areas of variable size on the tuber surface.

A tan to brown granular dry rot inside the tuber.

Dark blotches on the tuber surface.

Shrunken, discolored, and soft tubers.

25
Q

Foliar symptoms on tomatoes?

A

Water-soaked spots on the leaves, usually light to dark green or yellow in color

Brown or black lesions on the lower leaves, often near the leaf tips or edges

White or gray fuzzy growth on the leaf underside/ lesions, which is the spore production of the fungus

26
Q

Tomato fruit symptoms of late blight?

A

Leaf, stem, and fruit lesions that have a water-soaked appearance.

Lesions that eventually turn brown and the plant looks like it has been frost-damaged or blasted by a blowtorch.

Infected tomato fruits develop shiny, dark, or olive-colored lesions which may cover large areas

27
Q

What are lesions on plants?

A

Lesions in plants refer to localized, defined areas of diseased tissue

28
Q

Late blight on petunia symptoms

A

Symptoms of late blight include dark, water-soaked lesions on leaves, often with fuzzy white sporulation on the underside. Lesions can also occur on stems.

29
Q

How long after inocultion do symptoms appear on petunia?
How long after inoculation does infected petunia turn into “mush”

A

8 days
14 days

30
Q

How did P.infestans get into Europe?

A

Potato tuber latently infected
with pathogen brought to
Europe from P. infestans
centre of origin

  • Controversial
    –central Mexico - wild Solanum spp. (potato) occur
    –Andes in South America
  • origin of cultivated
    hosts tomato & potato
31
Q

How could one of a few
infected potato tubers cause such a big destruction?

A

P. infestans likely present Ireland few
fields prior to 1845
* climatic conditions prior 1845 unfavourable
late blight development

In 1844 potato yields excessively high
* huge amounts of excess potatoes disposed
cull piles
* Cull piles early spring contain many
sprouting potatoes
* Only one P. infestans infected tuber
required in cull pile to cause epidemic
* Huge amounts of spores produced cull
pile spread through wind to potato crops

32
Q

Why did the irish potato undergo famine (extreme scarcity of food)?

A

The Irish potato crops failed 7 years in a row due to late blight

33
Q

What were the 3 feared human diseases?

A
  • Dysentery
  • Typhus
  • Relapsing fewer
34
Q

How many people died due to the Irish potato famine?

A

More than i million irish people

35
Q

How mant Irish people emigrated due to the famine and for how long?

A

1.5 million people emigrated for several years

36
Q

What was the Irish population before and after the famine?

A

Irish population dropped from 8 million before famine to 5 million at end of famine

37
Q

Why did this human emigration shape history of USA and Britain (From famine)

A

John Fitzgeral Kennedy became president USA in 1960
* Descendant of two families that left Ireland to escape the famine

38
Q

Explain Late blight and WW1 in detail

A

In July 1914 war broke out involving Austria, Serbia,
Germany and Russia - developed into world war I

  • Germans hoped for quick victory but war continued 4
    years
  • Germany in good position at start of war
  • good chemists making explosives
  • crops were phenomenally good
  • In 1915 record potato crop recorded - yields nearly
    three times higher previous years
    -Food
    -Alcohol
    -Feeding livestock

All surplus potatoes ordered German government to be
stored
- Warm basements public buildings where surplus started rotting
- Not enough space to store everything and cull piles were
numerous

  • Potato crop of 1916 destroyed by clouds of spores from
    cull piles from 1915 crop
  • Potatoes that were available and grain yields were
    commandeered for German army
  • Seven hundred thousand German people (old, weak
    and children) starved to death during winter of 1916-17

Although Germany by 1916 could have turned fight
against Western Front
- many German soldiers lost their will for last war effort since
their families were hungry, starving and dying

  • Weakening of armies’ morale may have been one of
    reasons why the High Command never able to launch a
    successful campaigning in the West
  • Military might of Germany collapsed in November 1918
39
Q

When did the second Migration of P.infestans happen? And where did it occur?

A

In the 1990’s in USA and europe

40
Q

What likely caused the Irish famine

A

Only one genotype P.infestans
A1 mating type

41
Q

How many genotypes oh P.infestans occured world wide prior to 1990

A

Only one major genotype
US1–A1 mating type

42
Q

What where the new P.infestans genotypes that migrated to USA in 1990’s

A

A1 and A2 mating type

43
Q

Why was the A1 and A2 mating types worse after migration?

A

Caused much more severe disease

Resistant to some of the fungicides used to manage late blight

Sexual reproduction now possible

44
Q

What are the weather conditions that favour Late Blight?

A

*Low temperatures of 8-24 degrees celsius
optimum 15-20 degrees

  • Temperatures above 30C unfavorable for
    pathogen
  • High relative humidity (>75%) for at least 48h
45
Q

What did Dr. John Lindley note in 1846?

A

Dr. John Lindley in 1846 noted downwind from copper
works in Wales, potato fields green and healthy

46
Q

What did wine growers in France in 1885 use to control downy mildew?

A

Used Bordeuax mixture
(copper sulphate and lime)

47
Q

WHat happend when copper was sprayed on potatoes in 1890?

A

Copper sprayed on potato plants shown to kill
germinating spores and hyphae of pathogen

48
Q

Up to how many sprays per season are required when weather coditions are favorable?

A

15

49
Q

What are the cultural practices of today to contrl late blight

A

-Destroy cull piles

-Use disease free seed potatoes

-Cultivars vary in tolerance but commercially used cultivars are all susceptible

50
Q

What research is still conducted today by plant pathologists to try and lessen
economic losses caused by the “terrible plant destroyer”

A

-Pathogenicity factors of P. infestans
-Cultivar resistance breeding
-Fungicide testing
-Genetic and morphological characterization of P. infestans
populations
-Fungicide testin

Crop Protection 152 (4 decks)

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