2. Symptoms

Question 1

List five symptoms.

Answer 1

1. Abnormal color
2. Wilt
3. Death of host tissue or organ
4. Abnormal growth
5. Stunting

Question 2

What are the two main Abnormal color symptoms?

Answer 2

Chlorosis and Lesions.

Question 3

What is Chlorosis due to?

Answer 3

The yellowing of normally green tissue is due to chlorophyll destruction or failure of chlorophyll formation.

Question 4

Define Lesion.

Answer 4

A visible disease area.

Question 5

What type of Lesions can we identify on plants with abnormal color? (6)

Answer 5

1. Leaf spot (Mycosphaerlla-strwberry and Septoria)
2. Necrotic spot/dead lesion
3. Stripe
4. Mosaic
5. Blights
6. Blotch

Question 6

What is the discoloration delimited by in stripe lesions?

Answer 6

veins

Question 7

What are stripe lesions caused by?

Answer 7

virus, minerals and rust

Question 8

Define Blights.

Answer 8

A disease characterized by general and rapid killing of leaves, flowers and stems. (late blight)

Question 9

Define Blotch.

Answer 9

A disease characterized by large, and irregular in shape, spots or blots on leaves, shoots and stems.

Question 10

What is wilting caused by?

Answer 10

The loss of rigidity and drooping of plant partsis generally caused by water insufficiency in the plant. (Higher fungi-Ascomycota: Fusarium sp. and Bacteria: Erwinia sp.)

Question 11

What are the four symptoms under Death of host tissue or organ?

Answer 11

1. Rots (severe rot=leak: Pythium)
2. Damping off (Pythium)
3. Canker
4. Dieback

Question 12

What are rots caused by?

Answer 12

The softening, discoloration and often desintegration of a succulent plant tissue is caused by fungal or bacterial infection.
(soft rot of potato, fruit rots, stalk rot of corn)

Question 13

Define Damping off.

Answer 13

Destruction of seedlings near the soil line, resulting in the seedlings falling over on the ground.
(Higher fungi-Basidiomycota: Rhizoctonia and Chromista-Oomycota: Pythium)

Question 14

Define Canker.

Answer 14

A necrotic, often sunken lesion on a stem, branch, or twig of a plant. (Fungi and bacteria)

Question 15

Define Dieback.

Answer 15

Progressive death of shoots, branches and roots generally starting at the tip.

Question 16

What are the two symptoms under Abnormal growth?

Answer 16

1. Scab

2. Galls

Question 17

Define Scab.

Answer 17

A roughened, crust-like diseased area on the surface of a plant organ. (Fungi and Bacteria)

Question 18

Define Galls.

Answer 18

A swelling or overgrowth produces on a plant as a result of infection by pathogens due to hypertrophy=cell enlargement or hyperplasia= increase in cell division.

Question 19

Define stunting.

Answer 19

Dwarfing or reduces growth of the plant in general associated with reduction in size of the plant and yield.

Question 20

Define what signs are.

Answer 20

The pathogen or its parts or products seen on a host plant.

Question 21

List the five typical signs.

Answer 21

1. Mycelia, spores, conidia, fruiting body- asexual or sexual, sporangiophore or sclerotia, etc.
2. Downy mildew
3. Powdery mildew
4. Rusts
5. Smuts

Question 22

What is Downy mildew?

Answer 22

A fungal disease where mycelia, sporangiophore and sporangia of the fungus are seen as white downy or fluffy growth on the surface of the plant or plant part.
(Chromista)

Question 23

What is Powdery mildew?

Answer 23

A fungal disease where mycelia and conidia of the fungus are seen as a whitish powdery growth on the surface.
(Higher fungi: Ascomycete in Ascomycota fungi)

Question 24

What are Rusts?

Answer 24

A disease giving rusty appearance to a plant; produce pustules which rupture and expose:

• Uredospores in uredia
• Teliospores in telia
• Aecia
• Pycnia

Question 25

What are Smuts?

Answer 25

A disease characterized by masses of dark, powdery spores.

Smut fungi