Canola black leg disease

Question 1

What is the scientific name for Canola?

Answer 1

Brassica Napus

Question 2

How much has canola contributed to the Canadian economy?

Answer 2

29.9 billion

Question 3

What are the two major diseases in Canola?

Answer 3

1. Blackleg
2. Sclerotinia Stem rot

Question 4

What kind of a fungal species causes blackleg?

Answer 4

Ascomycete fungal species

Question 5

Which part of the plant does blackleg occur at?

Answer 5

leaf lesions, stem lesions and stem canker

Question 6

China is the only country to have one blackleg species. Which blackleg species is this?

Answer 6

L. biglobosa

Question 7

What are a few symptoms of blackleg?

Answer 7

1. STEM Canker
2. Dry rot or canker at the base of the stem.
3. Plants ripen prematurely.
4. Lodging
5. Seeds shrivel and pods shatter easily.

Question 8

What is a sign of blackleg?

Answer 8

Black dots

Question 9

What is the difference between large black dots and small black dots?

Answer 9

Small black dots are Pycnidia (Asexual fruiting body)

Large black dots are Pseudothesia (sexual fruiting body)

Question 10

What is a symptom of Verticillium?

Answer 10

Hollow stem

Question 11

What is another name for blackleg?

Answer 11

Root canker

Question 12

What are the two things we need to study and manage diseases?

Answer 12

1. Disease Triangle
2. Disease Cycle

Question 13

How can you alter host to manage disease triangle?

Answer 13

1. Crop rotation
2. Resistance Host

Question 14

How can you take care of pathogens to manage the disease triangle?

Answer 14

1. Take care of primary inoculum
2. Take care of secondary inoculum

Question 15

What kind of an environment does blackleg thrive in?

Answer 15

1. 5 - 20 degrees is optimal for pseudothecia growth.
2. Wet humid environment increase the severity due to increased dispersal of conidia by rain splash.
3. Wounds in plants increase severity.

Question 16

Briefly describe blackleg disease cycle

Answer 16

In the spring pseudothesia release ascospores. Cotyledons and young leaves show legions with pycnidia. Pycnidiospores are released and spread through rain splashes. Fungus grows from younger leaves to stems internally. This can lead to the lodging of the plant. The fungus overwinters on stubble.

Question 17

Name 3 black leg management strategies.

Answer 17

1. Crop rotation (4 years)
2. Fungicide application
3. Gene Resistance

Question 18

When does incompatible interaction between plant and pathogen happen?

Answer 18

When plat can recognize the pathogen.

Question 19

Why do we not use plants with the same R gene resistance for extended periods?

Answer 19

Because pathogens are smart and they can evolve different ways of infecting the plant. We call this R gene breakdown.

Question 20

Why are different R gene cultivars used?

Answer 20

Different R gene cultivars create immunity towards different pathogen genes. We use different R gene cultivars so the pathogen is not able to evolve as easily and this prevents R gene breakdown.