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Plant Pathology > Chromista, Oomycetes > Flashcards

Chromista, Oomycetes Flashcards

0
Q

Causal organism of damping off?

A

Pythium

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1
Q

What defines the kingdom Chromista?

A

Filamentus

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2
Q

Symptoms of damping off?

A

Seeds turn soft and mushy, no germination. Roots develop lesions, water soaked spots, and darkening. Stems develop necrotic spots, water soaking, and degradation. Older ants lose vigor. Produce water rot.

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3
Q

Signs of damping off?

A

White, fragile, slender mycelia growth (rare). Oospores in affected tissue.

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4
Q

Disease cycle of damping off?

A

Resting oospore - germinates around 68f producing sporangium - zoospores release - infect host - produce enzymes that cause tissue death - produce zoosporangia to produce zoospores and/or have sex to produce oospores

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5
Q

Favorable conditions for damping off?

A

Wet, cool.

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6
Q

Losses caused by damping off?

A

Seed, seedling losses, reduced stand, wilting and stunting of older, rotting of produce.

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7
Q

Management of damping off?

A

Sanitation, plant in correct conditions, do not over fertilize, seed treatment, improve drainage. No resistance available. Few fungicides affective against bc not a fungi.

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8
Q

Family if downy mildews?

A

Peronosporaceae

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9
Q

Significant about peronosporaceae?

A

Sporangea of determinate growth,wind borne, obligate parasites specialized to host.

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10
Q

Causal organism of downy mildew of grape?

A

Plasmopara viticola

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11
Q

Symptoms of downy mildew of grape?

A

Upper leaf surfaces - pale, bleached, yellow spots; spots become necrotic. Developing shoots are distorted. Berries wrinkle and toughen, develop reddish brown color.

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12
Q

Signs of downy mildew of grape?

A

Found on leaf undersides only in conditions of high moisture/ high humidity.

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13
Q

Disease cycle of downy mildew of grape?

A

Overwinters in woody stems or mycelium in infected parts; mycelium - symptoms and signs - cycle; oospores in debris - germinate in wet weather - form sporangia and oospores - wind borne/ rain borne - symptoms and signs - repeat at sporangia or senescence - sex - oospores.

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14
Q

Favorable conditions for downy mildew of grape.?

A

68-70f wet, high humidity

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15
Q

Losses from downy mildew of grape?

A

Plant vigor, quantity, quality.

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16
Q

Management for downy mildew of grape?

A

Resistance available especially in North American native varieties. Fungicide when needed - when wet at 7 to 10 day intervals. Bordeaux mixture.

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17
Q

Downy mildew of soybeans causal organism?

A

Peronospora manshrica

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18
Q

Symptoms of downy mildew of soybean?

A

Pale yellow spots on upper leaf surface.seed bleached. Some varieties have leaf and stem distortion.

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19
Q

Signs of downy mildew of soybean?

A

Sporangia on undersides of leaves.

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20
Q

Disease cycle of downy mildew of soybean?

A

Seed borne - systemic - symptoms and signs - sporangia and zoospores to repeat or oospores in debris; oospores in debris - germinate to sporangia and zoospores - infect to symptoms and signs - repeat or form oospores.

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21
Q

Favorable conditions for downy mildew of soybeans?

A

68-77f for infection. Wet high humidity. 50-80f for sporangia. Older leaves will develop resistance.

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22
Q

Losses from downy mildew of soybean?

A

Quantity and quality. Up to 20% loss in cool/ wet seasons.

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23
Q

Mangement of downy mildew of soybean?

A

Certified disease free seed. Rotate. Conventional tillage (debris management). No complete resistance but variations in susceptibility.

24
Q

Causal organism of potato late blight?

A

Phytophthora infestans

25
Q

Hosts of phytophthora infestans?

A

Solanaceae - tomatoes , potatoes peppers

26
Q

Symptoms of potato late blight?

A

Water soaked spots on leaf edges, spots expand rapidly killing leaves. Plants die. Tubers affected with purplish blotches, water soaked spots and rot. Putrid odor.

27
Q

Sign of potato late blight?

A

Downy white fungal growth on leaf edges.root lesions. In high humidity.

28
Q

Disease cycle of potato late blight?

A

Overwintering in tubers –organism grows with sprout - sporangia - wind borne - zoospores germinate with water - can wash into soil

29
Q

Favorable conditions for potato late blight?

A

Cool and moist 50-80f. Prolonged periods of wet.

30
Q

Losses from potato late blight.?

A

Loss of vigor.decreased quantity, plant death. Tubers rot.

31
Q

Management of potato late blight?

A

Resistance, sanitation, clean tubers, destroy cull pile. Fungicides.

32
Q

Causal organism sudden oak death?

A

Phytophthora ramorum

33
Q

Hosts of phytophthora ramorum?

A

Over 100 trees and ornamentals

.

34
Q

Geographical distribution of sudden oak death?

A

Pacific coast and possibly Deep South.

35
Q

Symptoms of sudden oak death?

A

Tree death. Cankers. Bleeding, necrosis. Defoliation.

36
Q

Signs of sudden oak death?

A

May find sporangia on affected leaves.

37
Q

Disease cycle of sudden oak death?

A

Over winters with chlamydospores(dark protective coating) - germinate to sporangia - wind borne - infect - cankers ooze - sporangia - repeat

38
Q

Favorable conditions for sudden oak death?

A

Extended periods of moisture. Temp 60-70f for zoospores but 80ish for infection

39
Q

Loses from sudden oak death?

A

Rapid plant death less than 2 years in mature oak less than one in woody ornamentals

40
Q

Management of sudden oak death?

A

Eradicate burn infected. Monitor for disease and quarantine questionable shipment. Little can be done no fungicide.

41
Q

Causal organism of potato late blight?

A

Phytophthora infestans

42
Q

Hosts of phytophthora infestans?

A

Solanaceae - tomatoes , potatoes peppers

43
Q

Symptoms of potato late blight?

A

Water soaked spots on leaf edges, spots expand rapidly killing leaves. Plants die. Tubers affected with purplish blotches, water soaked spots and rot. Putrid odor.

44
Q

Sign of potato late blight?

A

Downy white fungal growth on leaf edges.root lesions. In high humidity.

45
Q

Disease cycle of potato late blight?

A

Overwintering in tubers –organism grows with sprout - sporangia - wind borne - zoospores germinate with water - can wash into soil

46
Q

Favorable conditions for potato late blight?

A

Cool and moist 50-80f. Prolonged periods of wet.

47
Q

Losses from potato late blight.?

A

Loss of vigor.decreased quantity, plant death. Tubers rot.

48
Q

Management of potato late blight?

A

Resistance, sanitation, clean tubers, destroy cull pile. Fungicides.

49
Q

Causal organism sudden oak death?

A

Phytophthora ramorum

50
Q

Hosts of phytophthora ramorum?

A

Over 100 trees and ornamentals

.

51
Q

Geographical distribution of sudden oak death?

A

Pacific coast and possibly Deep South.

52
Q

Symptoms of sudden oak death?

A

Tree death. Cankers. Bleeding, necrosis. Defoliation.

53
Q

Signs of sudden oak death?

A

May find sporangia on affected leaves.

54
Q

Disease cycle of sudden oak death?

A

Over winters with chlamydospores(dark protective coating) - germinate to sporangia - wind borne - infect - cankers ooze - sporangia - repeat

55
Q

Favorable conditions for sudden oak death?

A

Extended periods of moisture. Temp 60-70f for zoospores but 80ish for infection

56
Q

Loses from sudden oak death?

A

Rapid plant death less than 2 years in mature oak less than one in woody ornamentals

57
Q

Management of sudden oak death?

A

Eradicate burn infected. Monitor for disease and quarantine questionable shipment. Little can be done no fungicide.

Plant Pathology (10 decks)

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