Bacterial diseases

Question 1

What are prokaryotes?

Answer 1

Usually single cellular organisms with no nucleus.

Question 2

What is a gram test?

Answer 2

It is a test that helps determine if a bacteria is gram-positive or gram-negative.

Question 2

What is the difference between a gram positive vs. a gram negative bacteria?

Answer 2

Gram-positive bacteria have a thicker layer of peptidoglycan on the cell wall whereas gram-negative bacteria have a thinner layer of peptidoglycan but instead they have an outer membrane.

Question 3

Why is it important to know if a bacteria is gram-positive or gram-negative?

Answer 3

The different bacteria react differently to different pesticides.

Question 4

How can you differentiate between gram positive and gram negative bacteria through a KOH test?

Answer 4

Gram -ve will be viscous slime and gram +ve will be no slime.

Question 5

How can you differentiate between gram positive and gram negative bacteria through a gram staining test?

Answer 5

Gram +ve bacteria will stain purple whereas gram -ve bacteria will stain either pink or red.

Question 6

What is one requirement for the bacteria to infect the plant?

Answer 6

Usually requires a critical mass of bacteria to colonize the host before infection.

Question 7

What are 5 ways bacteria can spread?

Answer 7

1. Wind
2. Rain
3. Aerosols
4. Insects, Birds
5. Humans

Question 8

What are six symptoms caused by bacterial infections?

Answer 8

1. Spots
2. Rots
3. Blights
4. Galls
5. Corks
6. Wilts

Question 9

What are four signs produced by bacteria?

Answer 9

1. Bacterial exudate
2. Slimy when fresh
3. Bacterial ooze
4. Streaming of Ooze

Question 10

What are four symptoms of gram negative bacteria?

Answer 10

1. Spots and blights.
2. Rots
3. Galls
4. Vascular Wilts

Question 11

What is one symptom of gram positive bacteria?

Answer 11

Common Scab

Question 12

What were the two bacteria we swabbed in lab?

Answer 12

Xanthomonas translucens and Clavibacter

Question 13

What kind of a bacteria is Xanthomonas translucens?

Answer 13

It is a gram-negative, non-spore-forming bacterium.

Question 14

What bacteria causes bacterial leaf streak?

Answer 14

Xanthomonas translucens.

Question 15

What are the four host plants for bacterial leaf streak?

Answer 15

1. Wheat
2. Barley
3. Rye
4. Triticale

Question 16

How much yield can bacterial leaf streak reduce?

Answer 16

~40%

Question 17

What are some signs and symptoms of bacterial leaf streak?

Answer 17

Water soaked streaks that develop into legions over time and yellow bacterial ooze on the surface of the leaves.

Question 18

How can bacterial leaf streak spread?

Answer 18

Rain, winds, and aphids.

Question 19

What does bacterial leaf streak eventually lead to?

Answer 19

It eventually leads to the flag leaves dying off and that leads to the plant unable to produce chlorophyll.

Question 20

What is black chaff?

Answer 20

Black chaff is a symptom of bacterial leaf streak. This occurs when the bacteria has traveled to the plant’s head and results in legions on the head.

Question 21

How does bacterial leaf streak survive?

Answer 21

Perennial weeds, and seeds of infected plants.

Question 22

What are the favorable conditions for the growth of bacterial leaf streaks?

Answer 22

-Humidity
-15 - 30 degrees C
-Wounds for the bacterial to enter through.

Question 23

What are four ways to control bacterial leaf streak?

Answer 23

1. Use of certified seeds
2. Treat seeds at 45 degrees for 20 mins.
3. Resistant cultivars.
4. Eliminating weed hosts and rotating to non-hosts.

Question 24

What bacteria causes Goss's bacterial wilt and leaf blight in corn?

Answer 24

Cavibacter michiganensis

Question 25

What kind of a bacteria is Cavibacter michiganensis?

Answer 25

It is a gram-positive bacteria.

Question 26

Where does cavibacter michiganesis overwinter?

Answer 26

In corn plant residue or other prairie grasses.

Question 27

How does Goss's bacterial wilt spread?

Answer 27

It can spread through seeds and wounds.

Question 28

What are the favorable conditions for the growth of Goss's bacterial wilt?

Answer 28

Wet weather and high humidity.

Question 29

What are the two phases of Goss's bacterial wilt?

Answer 29

1. Systemic wilt 2. Foliar blight (Blight on the foliage)

Question 30

What are two symptoms exhibited during the systematic wilt phase of Goss's bacterial wilt?

Answer 30

1. In the cross-section of the stalk, vascular bundles have an orange color which turns brown after disease progression. 2. Wilting

Question 31

What are 1 sign and 2 symptoms exhibited during the foliar blight phase of Goss's bacterial wilt?

Answer 31

1. Sign: Bacterial ooze or exudate. The exudate usually appears shiny and white. 2. Symptom: Black freckles. 3. Symptom: Water soaked legions first which lead to streaks of tan legions at the edges of leaf blades.

Question 32

What are the 4 ways to control Goss's wilt?

Answer 32

1. Reduce corn residue. 2. Genetic resistance. 3. Control weeds that are hosts for this disease. 4. Prevention/Avoidance: Harvest and till affected fields last and make sure to clean equipment to prevent spread.