Download Canola Diseases: THE BACK POCKET GUIDE

Individual plants or
patches die
Phytophthora root rot, Sclerotinia stem rot
Plants infected by Phytophthora root rot, begin to die and
are easily pulled up. Infected roots show decay and a dark
discolouration. Plants can be infected individually, or in
patches which are often low-lying wet areas. Most common
on poorly drained, heavy soils.
Root decay and
discolouration caused by
Phytophthora root rot.
Sclerotinia stem rot
infection appears as white
fluffy growth on stem.
Sclerotinia stem rot appears as white fluffy growth on the stem.
Crop growth stops above this point and severely affected plants
will die and lodge. Affected area on the plant is usually greyish
white or brownish white. Black, irregular-shaped fungal fruiting
bodies (sclerotia) form on and in stems.
Favoured by warm, damp spring weather during flowering.
Black sclerotia in stems.
Blotches with black specks
Blackleg
Grey, circular spots with black fruiting bodies (specks) forming
in the centre. Lesions can appear on any part of the plant at
any growth stage, with leaf lesions occurring even on resistant
varieties. Stem canker occurs later in the season and affected
plants will lodge, producing little or no seed.
Canker on the base of stem
Leaf Lesions
Blotches with dark
margins
Alternaria leaf spot
Alternaria spots on a
canola stem.
Alternaria spots on a
canola pod.
Dark target-like round spots that commonly appear on leaves,
but can also infect stems and pods. Pods severely infected can
become covered with spots causing them to prematurely shatter
and seed to shrivel. Infection spreads with wet, humid weather
during spring. Seed from infected pods can cause seedling
blight if sown.
Alternaria spots on a canola leaf. Note the target-like
appearance and the chlorotic halo on the leaf.
Flower heads distorted
White rust
Whitish cream pustules may form on leaves, stems, flower heads
or pods. The infection distorts the flower head, causing it to
enlarge and resemble a stag’s head.
Not common in canola crops, but more common in Brassica
rapa (Turnip rape) and B. juncea (Indian mustard).
Favoured by cool, moist conditions.
Distorted flower
heads.
This guide should be used in association with the
following publications:
• Canola: The Ute Guide
• Your Guide to Growing Golden Canola, Agriculture
Western Australia
• ‘Fungal diseases of canola in Western Australia’,
Department of Agriculture, WA, Bulletin 4406.
• Canola, NSW Agriculture
• Canola Check Tool Kit, Primary Industries and Resources SA
• Canola Cache, Kondinin Group
Each state department of agriculture / primary industries also have
a series of farm notes / fact sheets on canola production which are
updated on a regular basis.
Guide concept: Ross Andrews, GRDC
Photography: Stephen Marcroft, Mark Stanley, Roger Jones,
Martin Borbetti
Text: Stephen Marcroft, Trent Potter, Roger Jones
Any recommendations contained in this
publication do not necessarily represent
GRDC policy. No person should act on the
basis of the contents of this publication,
whether as to matters of fact or opinion or
other content, without first obtaining
specific, independent professional advice
which confirms the information contained
in this publication.
The “Managing Blackleg and Sclerotinia in Canola”
Back Pocket Guide is part of a series of Back Pocket
Guides published by GRDC.
For free copies please contact:
GRDC Publications Manager
PO Box E6 Kingston, ACT 2604
Telephone: 02 6272 5525
Facsimile: 02 6271 6430
Email:
[email protected]
GRDC
Grains
Research &
Development
Corporation
POCKET GUIDE
Canola Diseases: THE BACK
Using
this
Guide
This guide will help you identify the common
root, crown and leaf diseases that cause
damage to canola crops across Australia.
Some of the diseases can be initially identified
from paddock symptoms whilst others require
a more careful inspection of the root, lower
stems or leaves. Patches, or otherwise poorly
performing crops, can also be caused by
other factors such as poor nutrition, soil
problems, insect pests or environmental
stresses that are not covered in this guide.
Poor emergence &
seedling death
Damping off, Rhizoctonia hypocotyl rot
Damping off is caused by Pythium, Rhizoctonia and Fusarium sp.
Affected seedlings either fail to emerge or collapse at ground
level in patches, with leaves turning orange. These diseases
occur when conditions are unfavourable for germination and
early seedling growth, particularly during cold wet conditions.
Rhizoctonia hypocotyl rot is distinguished by a red-brown to
dark-brown lesion which develops on the hypocotyl as it pushes
through the soil. Seedlings become pinched off and break at
ground level. Cotyledons of infected plants turn red. Plants that
survive to the 3 to 4 leaf stage usually continue to grow.
Damping off caused by
Pythium and Fusarium sp.
Rhizoctonia hypocotyl rot
(seedling on the left).
Surface fungal growth
on leaves
Downy mildew, Powdery mildew
Yellow blotches caused by downy mildew.
Powdery mildew is identified by white powdery fungal growth
covering the stems, leaves and pods. The infected area is initially
white, then turns black after a period of time. Occurs mostly
under humid conditions in thick crops and when nitrogen
nutrition is good. Not a significant disease in canola crops.
Powdery mildew infection
on stem.
Powdery mildew infection
on leaves.
Downy mildew is very common in canola crops, it produces
yellow blotches on the upper leaf surface, and white mealy
growth on the underside. It is rarely found after the vegetative
stage of the crop, with little effect on crop performance.
Favoured by wet, cool conditions where leaves are in contact
with the soil or other leaves. Rapidly growing plants produce
new uninfected leaves and grow away from the disease.
Powdery mildew infection
on pods.
Plants distorted
Stem nematode and viruses
Stem nematode distorts the leaves emerging from the crown
of the plant, with reduced leaf area either side of the midrib.
The crown is very compact giving a swollen appearance.
High nematode numbers can lead to poor crop emergence.
The disease usually appears in patches, but can affect whole
crops. Seedlings are very intolerant but plants become more
resistant with maturity.
Crown is compact with leaves narrow and distorted.
Virus infection can also cause plant and pod distortion.
The disease usually appears in patches.
Discoloured leaves and
plant stunting
Beet western yellows, cauliflower mosaic and
turnip mosaic viruses
Photo Department of Agriculture, WA
These three viruses occur in canola crops. Infection with beet
western yellows virus is very common and most serious
economically. Yields can be drastically reduced when infection
occurs early and incidences of infection are high. Beet western
yellows is only transmitted by Green Peach aphid while the
other two viruses can be transmitted by any aphids, including
the Turnip and Cabbage aphids which, along with Green
Peach aphid, are the ones that colonise canola.
Cauliflower mosaic virus causes distortion of new
flower buds; pale mottling and ring spots.
Viruses cause a range of symptoms including leaf reddening,
pallor, mottling, vein netting and ring spots, reduction in leaf
size and plant dwarfing. Pods may also be twisted and distorted.
Photos Department of Agriculture, WA
Infected lucerne pastures, weeds and volunteer canola carry
canola viruses over from one year to the next. They are spread
to crops by aphids.
Beet western yellows virus damage an seedlings (left)
and flowering plants (right). Note the distinctive leaf
reddening.
Blotches with light brown
margins
White leaf rust (spot)
Greyish white to brown leaf, stem and pod lesions that have a
brown margin. Leaf lesions up to 10 mm in diameter. Can result
in defoliation of plants. Develops after periods of high rainfall.
Using
this
Guide
This guide will help you identify the common
root, crown and leaf diseases that cause
damage to canola crops across Australia.
Some of the diseases can be initially identified
from paddock symptoms whilst others require
a more careful inspection of the root, lower
stems or leaves. Patches, or otherwise poorly
performing crops, can also be caused by
other factors such as poor nutrition, soil
problems, insect pests or environmental
stresses that are not covered in this guide.
Poor emergence &
seedling death
Damping off, Rhizoctonia hypocotyl rot
Damping off is caused by Pythium, Rhizoctonia and Fusarium sp.
Affected seedlings either fail to emerge or collapse at ground
level in patches, with leaves turning orange. These diseases
occur when conditions are unfavourable for germination and
early seedling growth, particularly during cold wet conditions.
Rhizoctonia hypocotyl rot is distinguished by a red-brown to
dark-brown lesion which develops on the hypocotyl as it pushes
through the soil. Seedlings become pinched off and break at
ground level. Cotyledons of infected plants turn red. Plants that
survive to the 3 to 4 leaf stage usually continue to grow.
Damping off caused by
Pythium and Fusarium sp.
Rhizoctonia hypocotyl rot
(seedling on the left).
Surface fungal growth
on leaves
Downy mildew, Powdery mildew
Yellow blotches caused by downy mildew.
Powdery mildew is identified by white powdery fungal growth
covering the stems, leaves and pods. The infected area is initially
white, then turns black after a period of time. Occurs mostly
under humid conditions in thick crops and when nitrogen
nutrition is good. Not a significant disease in canola crops.
Powdery mildew infection
on stem.
Powdery mildew infection
on leaves.
Downy mildew is very common in canola crops, it produces
yellow blotches on the upper leaf surface, and white mealy
growth on the underside. It is rarely found after the vegetative
stage of the crop, with little effect on crop performance.
Favoured by wet, cool conditions where leaves are in contact
with the soil or other leaves. Rapidly growing plants produce
new uninfected leaves and grow away from the disease.
Powdery mildew infection
on pods.
Plants distorted
Stem nematode and viruses
Stem nematode distorts the leaves emerging from the crown
of the plant, with reduced leaf area either side of the midrib.
The crown is very compact giving a swollen appearance.
High nematode numbers can lead to poor crop emergence.
The disease usually appears in patches, but can affect whole
crops. Seedlings are very intolerant but plants become more
resistant with maturity.
Crown is compact with leaves narrow and distorted.
Virus infection can also cause plant and pod distortion.
The disease usually appears in patches.
Discoloured leaves and
plant stunting
Beet western yellows, cauliflower mosaic and
turnip mosaic viruses
Photo Department of Agriculture, WA
These three viruses occur in canola crops. Infection with beet
western yellows virus is very common and most serious
economically. Yields can be drastically reduced when infection
occurs early and incidences of infection are high. Beet western
yellows is only transmitted by Green Peach aphid while the
other two viruses can be transmitted by any aphids, including
the Turnip and Cabbage aphids which, along with Green
Peach aphid, are the ones that colonise canola.
Cauliflower mosaic virus causes distortion of new
flower buds; pale mottling and ring spots.
Viruses cause a range of symptoms including leaf reddening,
pallor, mottling, vein netting and ring spots, reduction in leaf
size and plant dwarfing. Pods may also be twisted and distorted.
Photos Department of Agriculture, WA
Infected lucerne pastures, weeds and volunteer canola carry
canola viruses over from one year to the next. They are spread
to crops by aphids.
Beet western yellows virus damage an seedlings (left)
and flowering plants (right). Note the distinctive leaf
reddening.
Blotches with light brown
margins
White leaf rust (spot)
Greyish white to brown leaf, stem and pod lesions that have a
brown margin. Leaf lesions up to 10 mm in diameter. Can result
in defoliation of plants. Develops after periods of high rainfall.
Using
this
Guide
This guide will help you identify the common
root, crown and leaf diseases that cause
damage to canola crops across Australia.
Some of the diseases can be initially identified
from paddock symptoms whilst others require
a more careful inspection of the root, lower
stems or leaves. Patches, or otherwise poorly
performing crops, can also be caused by
other factors such as poor nutrition, soil
problems, insect pests or environmental
stresses that are not covered in this guide.
Poor emergence &
seedling death
Damping off, Rhizoctonia hypocotyl rot
Damping off is caused by Pythium, Rhizoctonia and Fusarium sp.
Affected seedlings either fail to emerge or collapse at ground
level in patches, with leaves turning orange. These diseases
occur when conditions are unfavourable for germination and
early seedling growth, particularly during cold wet conditions.
Rhizoctonia hypocotyl rot is distinguished by a red-brown to
dark-brown lesion which develops on the hypocotyl as it pushes
through the soil. Seedlings become pinched off and break at
ground level. Cotyledons of infected plants turn red. Plants that
survive to the 3 to 4 leaf stage usually continue to grow.
Damping off caused by
Pythium and Fusarium sp.
Rhizoctonia hypocotyl rot
(seedling on the left).
Surface fungal growth
on leaves
Downy mildew, Powdery mildew
Yellow blotches caused by downy mildew.
Powdery mildew is identified by white powdery fungal growth
covering the stems, leaves and pods. The infected area is initially
white, then turns black after a period of time. Occurs mostly
under humid conditions in thick crops and when nitrogen
nutrition is good. Not a significant disease in canola crops.
Powdery mildew infection
on stem.
Powdery mildew infection
on leaves.
Downy mildew is very common in canola crops, it produces
yellow blotches on the upper leaf surface, and white mealy
growth on the underside. It is rarely found after the vegetative
stage of the crop, with little effect on crop performance.
Favoured by wet, cool conditions where leaves are in contact
with the soil or other leaves. Rapidly growing plants produce
new uninfected leaves and grow away from the disease.
Powdery mildew infection
on pods.
Plants distorted
Stem nematode and viruses
Stem nematode distorts the leaves emerging from the crown
of the plant, with reduced leaf area either side of the midrib.
The crown is very compact giving a swollen appearance.
High nematode numbers can lead to poor crop emergence.
The disease usually appears in patches, but can affect whole
crops. Seedlings are very intolerant but plants become more
resistant with maturity.
Crown is compact with leaves narrow and distorted.
Virus infection can also cause plant and pod distortion.
The disease usually appears in patches.
Discoloured leaves and
plant stunting
Beet western yellows, cauliflower mosaic and
turnip mosaic viruses
Photo Department of Agriculture, WA
These three viruses occur in canola crops. Infection with beet
western yellows virus is very common and most serious
economically. Yields can be drastically reduced when infection
occurs early and incidences of infection are high. Beet western
yellows is only transmitted by Green Peach aphid while the
other two viruses can be transmitted by any aphids, including
the Turnip and Cabbage aphids which, along with Green
Peach aphid, are the ones that colonise canola.
Cauliflower mosaic virus causes distortion of new
flower buds; pale mottling and ring spots.
Viruses cause a range of symptoms including leaf reddening,
pallor, mottling, vein netting and ring spots, reduction in leaf
size and plant dwarfing. Pods may also be twisted and distorted.
Photos Department of Agriculture, WA
Infected lucerne pastures, weeds and volunteer canola carry
canola viruses over from one year to the next. They are spread
to crops by aphids.
Beet western yellows virus damage an seedlings (left)
and flowering plants (right). Note the distinctive leaf
reddening.
Blotches with light brown
margins
White leaf rust (spot)
Greyish white to brown leaf, stem and pod lesions that have a
brown margin. Leaf lesions up to 10 mm in diameter. Can result
in defoliation of plants. Develops after periods of high rainfall.
Using
this
Guide
This guide will help you identify the common
root, crown and leaf diseases that cause
damage to canola crops across Australia.
Some of the diseases can be initially identified
from paddock symptoms whilst others require
a more careful inspection of the root, lower
stems or leaves. Patches, or otherwise poorly
performing crops, can also be caused by
other factors such as poor nutrition, soil
problems, insect pests or environmental
stresses that are not covered in this guide.
Poor emergence &
seedling death
Damping off, Rhizoctonia hypocotyl rot
Damping off is caused by Pythium, Rhizoctonia and Fusarium sp.
Affected seedlings either fail to emerge or collapse at ground
level in patches, with leaves turning orange. These diseases
occur when conditions are unfavourable for germination and
early seedling growth, particularly during cold wet conditions.
Rhizoctonia hypocotyl rot is distinguished by a red-brown to
dark-brown lesion which develops on the hypocotyl as it pushes
through the soil. Seedlings become pinched off and break at
ground level. Cotyledons of infected plants turn red. Plants that
survive to the 3 to 4 leaf stage usually continue to grow.
Damping off caused by
Pythium and Fusarium sp.
Rhizoctonia hypocotyl rot
(seedling on the left).
Surface fungal growth
on leaves
Downy mildew, Powdery mildew
Yellow blotches caused by downy mildew.
Powdery mildew is identified by white powdery fungal growth
covering the stems, leaves and pods. The infected area is initially
white, then turns black after a period of time. Occurs mostly
under humid conditions in thick crops and when nitrogen
nutrition is good. Not a significant disease in canola crops.
Powdery mildew infection
on stem.
Powdery mildew infection
on leaves.
Downy mildew is very common in canola crops, it produces
yellow blotches on the upper leaf surface, and white mealy
growth on the underside. It is rarely found after the vegetative
stage of the crop, with little effect on crop performance.
Favoured by wet, cool conditions where leaves are in contact
with the soil or other leaves. Rapidly growing plants produce
new uninfected leaves and grow away from the disease.
Powdery mildew infection
on pods.
Plants distorted
Stem nematode and viruses
Stem nematode distorts the leaves emerging from the crown
of the plant, with reduced leaf area either side of the midrib.
The crown is very compact giving a swollen appearance.
High nematode numbers can lead to poor crop emergence.
The disease usually appears in patches, but can affect whole
crops. Seedlings are very intolerant but plants become more
resistant with maturity.
Crown is compact with leaves narrow and distorted.
Virus infection can also cause plant and pod distortion.
The disease usually appears in patches.
Discoloured leaves and
plant stunting
Beet western yellows, cauliflower mosaic and
turnip mosaic viruses
Photo Department of Agriculture, WA
These three viruses occur in canola crops. Infection with beet
western yellows virus is very common and most serious
economically. Yields can be drastically reduced when infection
occurs early and incidences of infection are high. Beet western
yellows is only transmitted by Green Peach aphid while the
other two viruses can be transmitted by any aphids, including
the Turnip and Cabbage aphids which, along with Green
Peach aphid, are the ones that colonise canola.
Cauliflower mosaic virus causes distortion of new
flower buds; pale mottling and ring spots.
Viruses cause a range of symptoms including leaf reddening,
pallor, mottling, vein netting and ring spots, reduction in leaf
size and plant dwarfing. Pods may also be twisted and distorted.
Photos Department of Agriculture, WA
Infected lucerne pastures, weeds and volunteer canola carry
canola viruses over from one year to the next. They are spread
to crops by aphids.
Beet western yellows virus damage an seedlings (left)
and flowering plants (right). Note the distinctive leaf
reddening.
Blotches with light brown
margins
White leaf rust (spot)
Greyish white to brown leaf, stem and pod lesions that have a
brown margin. Leaf lesions up to 10 mm in diameter. Can result
in defoliation of plants. Develops after periods of high rainfall.
Using
this
Guide
This guide will help you identify the common
root, crown and leaf diseases that cause
damage to canola crops across Australia.
Some of the diseases can be initially identified
from paddock symptoms whilst others require
a more careful inspection of the root, lower
stems or leaves. Patches, or otherwise poorly
performing crops, can also be caused by
other factors such as poor nutrition, soil
problems, insect pests or environmental
stresses that are not covered in this guide.
Poor emergence &
seedling death
Damping off, Rhizoctonia hypocotyl rot
Damping off is caused by Pythium, Rhizoctonia and Fusarium sp.
Affected seedlings either fail to emerge or collapse at ground
level in patches, with leaves turning orange. These diseases
occur when conditions are unfavourable for germination and
early seedling growth, particularly during cold wet conditions.
Rhizoctonia hypocotyl rot is distinguished by a red-brown to
dark-brown lesion which develops on the hypocotyl as it pushes
through the soil. Seedlings become pinched off and break at
ground level. Cotyledons of infected plants turn red. Plants that
survive to the 3 to 4 leaf stage usually continue to grow.
Damping off caused by
Pythium and Fusarium sp.
Rhizoctonia hypocotyl rot
(seedling on the left).
Surface fungal growth
on leaves
Downy mildew, Powdery mildew
Yellow blotches caused by downy mildew.
Powdery mildew is identified by white powdery fungal growth
covering the stems, leaves and pods. The infected area is initially
white, then turns black after a period of time. Occurs mostly
under humid conditions in thick crops and when nitrogen
nutrition is good. Not a significant disease in canola crops.
Powdery mildew infection
on stem.
Powdery mildew infection
on leaves.
Downy mildew is very common in canola crops, it produces
yellow blotches on the upper leaf surface, and white mealy
growth on the underside. It is rarely found after the vegetative
stage of the crop, with little effect on crop performance.
Favoured by wet, cool conditions where leaves are in contact
with the soil or other leaves. Rapidly growing plants produce
new uninfected leaves and grow away from the disease.
Powdery mildew infection
on pods.
Plants distorted
Stem nematode and viruses
Stem nematode distorts the leaves emerging from the crown
of the plant, with reduced leaf area either side of the midrib.
The crown is very compact giving a swollen appearance.
High nematode numbers can lead to poor crop emergence.
The disease usually appears in patches, but can affect whole
crops. Seedlings are very intolerant but plants become more
resistant with maturity.
Crown is compact with leaves narrow and distorted.
Virus infection can also cause plant and pod distortion.
The disease usually appears in patches.
Discoloured leaves and
plant stunting
Beet western yellows, cauliflower mosaic and
turnip mosaic viruses
Photo Department of Agriculture, WA
These three viruses occur in canola crops. Infection with beet
western yellows virus is very common and most serious
economically. Yields can be drastically reduced when infection
occurs early and incidences of infection are high. Beet western
yellows is only transmitted by Green Peach aphid while the
other two viruses can be transmitted by any aphids, including
the Turnip and Cabbage aphids which, along with Green
Peach aphid, are the ones that colonise canola.
Cauliflower mosaic virus causes distortion of new
flower buds; pale mottling and ring spots.
Viruses cause a range of symptoms including leaf reddening,
pallor, mottling, vein netting and ring spots, reduction in leaf
size and plant dwarfing. Pods may also be twisted and distorted.
Photos Department of Agriculture, WA
Infected lucerne pastures, weeds and volunteer canola carry
canola viruses over from one year to the next. They are spread
to crops by aphids.
Beet western yellows virus damage an seedlings (left)
and flowering plants (right). Note the distinctive leaf
reddening.
Blotches with light brown
margins
White leaf rust (spot)
Greyish white to brown leaf, stem and pod lesions that have a
brown margin. Leaf lesions up to 10 mm in diameter. Can result
in defoliation of plants. Develops after periods of high rainfall.
Using
this
Guide
This guide will help you identify the common
root, crown and leaf diseases that cause
damage to canola crops across Australia.
Some of the diseases can be initially identified
from paddock symptoms whilst others require
a more careful inspection of the root, lower
stems or leaves. Patches, or otherwise poorly
performing crops, can also be caused by
other factors such as poor nutrition, soil
problems, insect pests or environmental
stresses that are not covered in this guide.
Poor emergence &
seedling death
Damping off, Rhizoctonia hypocotyl rot
Damping off is caused by Pythium, Rhizoctonia and Fusarium sp.
Affected seedlings either fail to emerge or collapse at ground
level in patches, with leaves turning orange. These diseases
occur when conditions are unfavourable for germination and
early seedling growth, particularly during cold wet conditions.
Rhizoctonia hypocotyl rot is distinguished by a red-brown to
dark-brown lesion which develops on the hypocotyl as it pushes
through the soil. Seedlings become pinched off and break at
ground level. Cotyledons of infected plants turn red. Plants that
survive to the 3 to 4 leaf stage usually continue to grow.
Damping off caused by
Pythium and Fusarium sp.
Rhizoctonia hypocotyl rot
(seedling on the left).
Surface fungal growth
on leaves
Downy mildew, Powdery mildew
Yellow blotches caused by downy mildew.
Powdery mildew is identified by white powdery fungal growth
covering the stems, leaves and pods. The infected area is initially
white, then turns black after a period of time. Occurs mostly
under humid conditions in thick crops and when nitrogen
nutrition is good. Not a significant disease in canola crops.
Powdery mildew infection
on stem.
Powdery mildew infection
on leaves.
Downy mildew is very common in canola crops, it produces
yellow blotches on the upper leaf surface, and white mealy
growth on the underside. It is rarely found after the vegetative
stage of the crop, with little effect on crop performance.
Favoured by wet, cool conditions where leaves are in contact
with the soil or other leaves. Rapidly growing plants produce
new uninfected leaves and grow away from the disease.
Powdery mildew infection
on pods.
Plants distorted
Stem nematode and viruses
Stem nematode distorts the leaves emerging from the crown
of the plant, with reduced leaf area either side of the midrib.
The crown is very compact giving a swollen appearance.
High nematode numbers can lead to poor crop emergence.
The disease usually appears in patches, but can affect whole
crops. Seedlings are very intolerant but plants become more
resistant with maturity.
Crown is compact with leaves narrow and distorted.
Virus infection can also cause plant and pod distortion.
The disease usually appears in patches.
Discoloured leaves and
plant stunting
Beet western yellows, cauliflower mosaic and
turnip mosaic viruses
Photo Department of Agriculture, WA
These three viruses occur in canola crops. Infection with beet
western yellows virus is very common and most serious
economically. Yields can be drastically reduced when infection
occurs early and incidences of infection are high. Beet western
yellows is only transmitted by Green Peach aphid while the
other two viruses can be transmitted by any aphids, including
the Turnip and Cabbage aphids which, along with Green
Peach aphid, are the ones that colonise canola.
Cauliflower mosaic virus causes distortion of new
flower buds; pale mottling and ring spots.
Viruses cause a range of symptoms including leaf reddening,
pallor, mottling, vein netting and ring spots, reduction in leaf
size and plant dwarfing. Pods may also be twisted and distorted.
Photos Department of Agriculture, WA
Infected lucerne pastures, weeds and volunteer canola carry
canola viruses over from one year to the next. They are spread
to crops by aphids.
Beet western yellows virus damage an seedlings (left)
and flowering plants (right). Note the distinctive leaf
reddening.
Blotches with light brown
margins
White leaf rust (spot)
Greyish white to brown leaf, stem and pod lesions that have a
brown margin. Leaf lesions up to 10 mm in diameter. Can result
in defoliation of plants. Develops after periods of high rainfall.
Using
this
Guide
This guide will help you identify the common
root, crown and leaf diseases that cause
damage to canola crops across Australia.
Some of the diseases can be initially identified
from paddock symptoms whilst others require
a more careful inspection of the root, lower
stems or leaves. Patches, or otherwise poorly
performing crops, can also be caused by
other factors such as poor nutrition, soil
problems, insect pests or environmental
stresses that are not covered in this guide.
Poor emergence &
seedling death
Damping off, Rhizoctonia hypocotyl rot
Damping off is caused by Pythium, Rhizoctonia and Fusarium sp.
Affected seedlings either fail to emerge or collapse at ground
level in patches, with leaves turning orange. These diseases
occur when conditions are unfavourable for germination and
early seedling growth, particularly during cold wet conditions.
Rhizoctonia hypocotyl rot is distinguished by a red-brown to
dark-brown lesion which develops on the hypocotyl as it pushes
through the soil. Seedlings become pinched off and break at
ground level. Cotyledons of infected plants turn red. Plants that
survive to the 3 to 4 leaf stage usually continue to grow.
Damping off caused by
Pythium and Fusarium sp.
Rhizoctonia hypocotyl rot
(seedling on the left).
Surface fungal growth
on leaves
Downy mildew, Powdery mildew
Yellow blotches caused by downy mildew.
Powdery mildew is identified by white powdery fungal growth
covering the stems, leaves and pods. The infected area is initially
white, then turns black after a period of time. Occurs mostly
under humid conditions in thick crops and when nitrogen
nutrition is good. Not a significant disease in canola crops.
Powdery mildew infection
on stem.
Powdery mildew infection
on leaves.
Downy mildew is very common in canola crops, it produces
yellow blotches on the upper leaf surface, and white mealy
growth on the underside. It is rarely found after the vegetative
stage of the crop, with little effect on crop performance.
Favoured by wet, cool conditions where leaves are in contact
with the soil or other leaves. Rapidly growing plants produce
new uninfected leaves and grow away from the disease.
Powdery mildew infection
on pods.
Plants distorted
Stem nematode and viruses
Stem nematode distorts the leaves emerging from the crown
of the plant, with reduced leaf area either side of the midrib.
The crown is very compact giving a swollen appearance.
High nematode numbers can lead to poor crop emergence.
The disease usually appears in patches, but can affect whole
crops. Seedlings are very intolerant but plants become more
resistant with maturity.
Crown is compact with leaves narrow and distorted.
Virus infection can also cause plant and pod distortion.
The disease usually appears in patches.
Discoloured leaves and
plant stunting
Beet western yellows, cauliflower mosaic and
turnip mosaic viruses
Photo Department of Agriculture, WA
These three viruses occur in canola crops. Infection with beet
western yellows virus is very common and most serious
economically. Yields can be drastically reduced when infection
occurs early and incidences of infection are high. Beet western
yellows is only transmitted by Green Peach aphid while the
other two viruses can be transmitted by any aphids, including
the Turnip and Cabbage aphids which, along with Green
Peach aphid, are the ones that colonise canola.
Cauliflower mosaic virus causes distortion of new
flower buds; pale mottling and ring spots.
Viruses cause a range of symptoms including leaf reddening,
pallor, mottling, vein netting and ring spots, reduction in leaf
size and plant dwarfing. Pods may also be twisted and distorted.
Photos Department of Agriculture, WA
Infected lucerne pastures, weeds and volunteer canola carry
canola viruses over from one year to the next. They are spread
to crops by aphids.
Beet western yellows virus damage an seedlings (left)
and flowering plants (right). Note the distinctive leaf
reddening.
Blotches with light brown
margins
White leaf rust (spot)
Greyish white to brown leaf, stem and pod lesions that have a
brown margin. Leaf lesions up to 10 mm in diameter. Can result
in defoliation of plants. Develops after periods of high rainfall.
Individual plants or
patches die
Phytophthora root rot, Sclerotinia stem rot
Plants infected by Phytophthora root rot, begin to die and
are easily pulled up. Infected roots show decay and a dark
discolouration. Plants can be infected individually, or in
patches which are often low-lying wet areas. Most common
on poorly drained, heavy soils.
Root decay and
discolouration caused by
Phytophthora root rot.
Sclerotinia stem rot
infection appears as white
fluffy growth on stem.
Sclerotinia stem rot appears as white fluffy growth on the stem.
Crop growth stops above this point and severely affected plants
will die and lodge. Affected area on the plant is usually greyish
white or brownish white. Black, irregular-shaped fungal fruiting
bodies (sclerotia) form on and in stems.
Favoured by warm, damp spring weather during flowering.
Black sclerotia in stems.
Blotches with black specks
Blackleg
Grey, circular spots with black fruiting bodies (specks) forming
in the centre. Lesions can appear on any part of the plant at
any growth stage, with leaf lesions occurring even on resistant
varieties. Stem canker occurs later in the season and affected
plants will lodge, producing little or no seed.
Canker on the base of stem
Leaf Lesions
Blotches with dark
margins
Alternaria leaf spot
Alternaria spots on a
canola stem.
Alternaria spots on a
canola pod.
Dark target-like round spots that commonly appear on leaves,
but can also infect stems and pods. Pods severely infected can
become covered with spots causing them to prematurely shatter
and seed to shrivel. Infection spreads with wet, humid weather
during spring. Seed from infected pods can cause seedling
blight if sown.
Alternaria spots on a canola leaf. Note the target-like
appearance and the chlorotic halo on the leaf.
Flower heads distorted
White rust
Whitish cream pustules may form on leaves, stems, flower heads
or pods. The infection distorts the flower head, causing it to
enlarge and resemble a stag’s head.
Not common in canola crops, but more common in Brassica
rapa (Turnip rape) and B. juncea (Indian mustard).
Favoured by cool, moist conditions.
Distorted flower
heads.
This guide should be used in association with the
following publications:
• Canola: The Ute Guide
• Your Guide to Growing Golden Canola, Agriculture
Western Australia
• ‘Fungal diseases of canola in Western Australia’,
Department of Agriculture, WA, Bulletin 4406.
• Canola, NSW Agriculture
• Canola Check Tool Kit, Primary Industries and Resources SA
• Canola Cache, Kondinin Group
Each state department of agriculture / primary industries also have
a series of farm notes / fact sheets on canola production which are
updated on a regular basis.
Guide concept: Ross Andrews, GRDC
Photography: Stephen Marcroft, Mark Stanley, Roger Jones,
Martin Borbetti
Text: Stephen Marcroft, Trent Potter, Roger Jones
Any recommendations contained in this
publication do not necessarily represent
GRDC policy. No person should act on the
basis of the contents of this publication,
whether as to matters of fact or opinion or
other content, without first obtaining
specific, independent professional advice
which confirms the information contained
in this publication.
The “Managing Blackleg and Sclerotinia in Canola”
Back Pocket Guide is part of a series of Back Pocket
Guides published by GRDC.
For free copies please contact:
GRDC Publications Manager
PO Box E6 Kingston, ACT 2604
Telephone: 02 6272 5525
Facsimile: 02 6271 6430
Email:
[email protected]
GRDC
Grains
Research &
Development
Corporation
POCKET GUIDE
Canola Diseases: THE BACK
Individual plants or
patches die
Phytophthora root rot, Sclerotinia stem rot
Plants infected by Phytophthora root rot, begin to die and
are easily pulled up. Infected roots show decay and a dark
discolouration. Plants can be infected individually, or in
patches which are often low-lying wet areas. Most common
on poorly drained, heavy soils.
Root decay and
discolouration caused by
Phytophthora root rot.
Sclerotinia stem rot
infection appears as white
fluffy growth on stem.
Sclerotinia stem rot appears as white fluffy growth on the stem.
Crop growth stops above this point and severely affected plants
will die and lodge. Affected area on the plant is usually greyish
white or brownish white. Black, irregular-shaped fungal fruiting
bodies (sclerotia) form on and in stems.
Favoured by warm, damp spring weather during flowering.
Black sclerotia in stems.
Blotches with black specks
Blackleg
Grey, circular spots with black fruiting bodies (specks) forming
in the centre. Lesions can appear on any part of the plant at
any growth stage, with leaf lesions occurring even on resistant
varieties. Stem canker occurs later in the season and affected
plants will lodge, producing little or no seed.
Canker on the base of stem
Leaf Lesions
Blotches with dark
margins
Alternaria leaf spot
Alternaria spots on a
canola stem.
Alternaria spots on a
canola pod.
Dark target-like round spots that commonly appear on leaves,
but can also infect stems and pods. Pods severely infected can
become covered with spots causing them to prematurely shatter
and seed to shrivel. Infection spreads with wet, humid weather
during spring. Seed from infected pods can cause seedling
blight if sown.
Alternaria spots on a canola leaf. Note the target-like
appearance and the chlorotic halo on the leaf.
Flower heads distorted
White rust
Whitish cream pustules may form on leaves, stems, flower heads
or pods. The infection distorts the flower head, causing it to
enlarge and resemble a stag’s head.
Not common in canola crops, but more common in Brassica
rapa (Turnip rape) and B. juncea (Indian mustard).
Favoured by cool, moist conditions.
Distorted flower
heads.
This guide should be used in association with the
following publications:
• Canola: The Ute Guide
• Your Guide to Growing Golden Canola, Agriculture
Western Australia
• ‘Fungal diseases of canola in Western Australia’,
Department of Agriculture, WA, Bulletin 4406.
• Canola, NSW Agriculture
• Canola Check Tool Kit, Primary Industries and Resources SA
• Canola Cache, Kondinin Group
Each state department of agriculture / primary industries also have
a series of farm notes / fact sheets on canola production which are
updated on a regular basis.
Guide concept: Ross Andrews, GRDC
Photography: Stephen Marcroft, Mark Stanley, Roger Jones,
Martin Borbetti
Text: Stephen Marcroft, Trent Potter, Roger Jones
Any recommendations contained in this
publication do not necessarily represent
GRDC policy. No person should act on the
basis of the contents of this publication,
whether as to matters of fact or opinion or
other content, without first obtaining
specific, independent professional advice
which confirms the information contained
in this publication.
The “Managing Blackleg and Sclerotinia in Canola”
Back Pocket Guide is part of a series of Back Pocket
Guides published by GRDC.
For free copies please contact:
GRDC Publications Manager
PO Box E6 Kingston, ACT 2604
Telephone: 02 6272 5525
Facsimile: 02 6271 6430
Email:
[email protected]
GRDC
Grains
Research &
Development
Corporation
POCKET GUIDE
Canola Diseases: THE BACK
Individual plants or
patches die
Phytophthora root rot, Sclerotinia stem rot
Plants infected by Phytophthora root rot, begin to die and
are easily pulled up. Infected roots show decay and a dark
discolouration. Plants can be infected individually, or in
patches which are often low-lying wet areas. Most common
on poorly drained, heavy soils.
Root decay and
discolouration caused by
Phytophthora root rot.
Sclerotinia stem rot
infection appears as white
fluffy growth on stem.
Sclerotinia stem rot appears as white fluffy growth on the stem.
Crop growth stops above this point and severely affected plants
will die and lodge. Affected area on the plant is usually greyish
white or brownish white. Black, irregular-shaped fungal fruiting
bodies (sclerotia) form on and in stems.
Favoured by warm, damp spring weather during flowering.
Black sclerotia in stems.
Blotches with black specks
Blackleg
Grey, circular spots with black fruiting bodies (specks) forming
in the centre. Lesions can appear on any part of the plant at
any growth stage, with leaf lesions occurring even on resistant
varieties. Stem canker occurs later in the season and affected
plants will lodge, producing little or no seed.
Canker on the base of stem
Leaf Lesions
Blotches with dark
margins
Alternaria leaf spot
Alternaria spots on a
canola stem.
Alternaria spots on a
canola pod.
Dark target-like round spots that commonly appear on leaves,
but can also infect stems and pods. Pods severely infected can
become covered with spots causing them to prematurely shatter
and seed to shrivel. Infection spreads with wet, humid weather
during spring. Seed from infected pods can cause seedling
blight if sown.
Alternaria spots on a canola leaf. Note the target-like
appearance and the chlorotic halo on the leaf.
Flower heads distorted
White rust
Whitish cream pustules may form on leaves, stems, flower heads
or pods. The infection distorts the flower head, causing it to
enlarge and resemble a stag’s head.
Not common in canola crops, but more common in Brassica
rapa (Turnip rape) and B. juncea (Indian mustard).
Favoured by cool, moist conditions.
Distorted flower
heads.
This guide should be used in association with the
following publications:
• Canola: The Ute Guide
• Your Guide to Growing Golden Canola, Agriculture
Western Australia
• ‘Fungal diseases of canola in Western Australia’,
Department of Agriculture, WA, Bulletin 4406.
• Canola, NSW Agriculture
• Canola Check Tool Kit, Primary Industries and Resources SA
• Canola Cache, Kondinin Group
Each state department of agriculture / primary industries also have
a series of farm notes / fact sheets on canola production which are
updated on a regular basis.
Guide concept: Ross Andrews, GRDC
Photography: Stephen Marcroft, Mark Stanley, Roger Jones,
Martin Borbetti
Text: Stephen Marcroft, Trent Potter, Roger Jones
Any recommendations contained in this
publication do not necessarily represent
GRDC policy. No person should act on the
basis of the contents of this publication,
whether as to matters of fact or opinion or
other content, without first obtaining
specific, independent professional advice
which confirms the information contained
in this publication.
The “Managing Blackleg and Sclerotinia in Canola”
Back Pocket Guide is part of a series of Back Pocket
Guides published by GRDC.
For free copies please contact:
GRDC Publications Manager
PO Box E6 Kingston, ACT 2604
Telephone: 02 6272 5525
Facsimile: 02 6271 6430
Email:
[email protected]
GRDC
Grains
Research &
Development
Corporation
POCKET GUIDE
Canola Diseases: THE BACK
Individual plants or
patches die
Phytophthora root rot, Sclerotinia stem rot
Plants infected by Phytophthora root rot, begin to die and
are easily pulled up. Infected roots show decay and a dark
discolouration. Plants can be infected individually, or in
patches which are often low-lying wet areas. Most common
on poorly drained, heavy soils.
Root decay and
discolouration caused by
Phytophthora root rot.
Sclerotinia stem rot
infection appears as white
fluffy growth on stem.
Sclerotinia stem rot appears as white fluffy growth on the stem.
Crop growth stops above this point and severely affected plants
will die and lodge. Affected area on the plant is usually greyish
white or brownish white. Black, irregular-shaped fungal fruiting
bodies (sclerotia) form on and in stems.
Favoured by warm, damp spring weather during flowering.
Black sclerotia in stems.
Blotches with black specks
Blackleg
Grey, circular spots with black fruiting bodies (specks) forming
in the centre. Lesions can appear on any part of the plant at
any growth stage, with leaf lesions occurring even on resistant
varieties. Stem canker occurs later in the season and affected
plants will lodge, producing little or no seed.
Canker on the base of stem
Leaf Lesions
Blotches with dark
margins
Alternaria leaf spot
Alternaria spots on a
canola stem.
Alternaria spots on a
canola pod.
Dark target-like round spots that commonly appear on leaves,
but can also infect stems and pods. Pods severely infected can
become covered with spots causing them to prematurely shatter
and seed to shrivel. Infection spreads with wet, humid weather
during spring. Seed from infected pods can cause seedling
blight if sown.
Alternaria spots on a canola leaf. Note the target-like
appearance and the chlorotic halo on the leaf.
Flower heads distorted
White rust
Whitish cream pustules may form on leaves, stems, flower heads
or pods. The infection distorts the flower head, causing it to
enlarge and resemble a stag’s head.
Not common in canola crops, but more common in Brassica
rapa (Turnip rape) and B. juncea (Indian mustard).
Favoured by cool, moist conditions.
Distorted flower
heads.
This guide should be used in association with the
following publications:
• Canola: The Ute Guide
• Your Guide to Growing Golden Canola, Agriculture
Western Australia
• ‘Fungal diseases of canola in Western Australia’,
Department of Agriculture, WA, Bulletin 4406.
• Canola, NSW Agriculture
• Canola Check Tool Kit, Primary Industries and Resources SA
• Canola Cache, Kondinin Group
Each state department of agriculture / primary industries also have
a series of farm notes / fact sheets on canola production which are
updated on a regular basis.
Guide concept: Ross Andrews, GRDC
Photography: Stephen Marcroft, Mark Stanley, Roger Jones,
Martin Borbetti
Text: Stephen Marcroft, Trent Potter, Roger Jones
Any recommendations contained in this
publication do not necessarily represent
GRDC policy. No person should act on the
basis of the contents of this publication,
whether as to matters of fact or opinion or
other content, without first obtaining
specific, independent professional advice
which confirms the information contained
in this publication.
The “Managing Blackleg and Sclerotinia in Canola”
Back Pocket Guide is part of a series of Back Pocket
Guides published by GRDC.
For free copies please contact:
GRDC Publications Manager
PO Box E6 Kingston, ACT 2604
Telephone: 02 6272 5525
Facsimile: 02 6271 6430
Email:
[email protected]
GRDC
Grains
Research &
Development
Corporation
POCKET GUIDE
Canola Diseases: THE BACK
Individual plants or
patches die
Phytophthora root rot, Sclerotinia stem rot
Plants infected by Phytophthora root rot, begin to die and
are easily pulled up. Infected roots show decay and a dark
discolouration. Plants can be infected individually, or in
patches which are often low-lying wet areas. Most common
on poorly drained, heavy soils.
Root decay and
discolouration caused by
Phytophthora root rot.
Sclerotinia stem rot
infection appears as white
fluffy growth on stem.
Sclerotinia stem rot appears as white fluffy growth on the stem.
Crop growth stops above this point and severely affected plants
will die and lodge. Affected area on the plant is usually greyish
white or brownish white. Black, irregular-shaped fungal fruiting
bodies (sclerotia) form on and in stems.
Favoured by warm, damp spring weather during flowering.
Black sclerotia in stems.
Blotches with black specks
Blackleg
Grey, circular spots with black fruiting bodies (specks) forming
in the centre. Lesions can appear on any part of the plant at
any growth stage, with leaf lesions occurring even on resistant
varieties. Stem canker occurs later in the season and affected
plants will lodge, producing little or no seed.
Canker on the base of stem
Leaf Lesions
Blotches with dark
margins
Alternaria leaf spot
Alternaria spots on a
canola stem.
Alternaria spots on a
canola pod.
Dark target-like round spots that commonly appear on leaves,
but can also infect stems and pods. Pods severely infected can
become covered with spots causing them to prematurely shatter
and seed to shrivel. Infection spreads with wet, humid weather
during spring. Seed from infected pods can cause seedling
blight if sown.
Alternaria spots on a canola leaf. Note the target-like
appearance and the chlorotic halo on the leaf.
Flower heads distorted
White rust
Whitish cream pustules may form on leaves, stems, flower heads
or pods. The infection distorts the flower head, causing it to
enlarge and resemble a stag’s head.
Not common in canola crops, but more common in Brassica
rapa (Turnip rape) and B. juncea (Indian mustard).
Favoured by cool, moist conditions.
Distorted flower
heads.
This guide should be used in association with the
following publications:
• Canola: The Ute Guide
• Your Guide to Growing Golden Canola, Agriculture
Western Australia
• ‘Fungal diseases of canola in Western Australia’,
Department of Agriculture, WA, Bulletin 4406.
• Canola, NSW Agriculture
• Canola Check Tool Kit, Primary Industries and Resources SA
• Canola Cache, Kondinin Group
Each state department of agriculture / primary industries also have
a series of farm notes / fact sheets on canola production which are
updated on a regular basis.
Guide concept: Ross Andrews, GRDC
Photography: Stephen Marcroft, Mark Stanley, Roger Jones,
Martin Borbetti
Text: Stephen Marcroft, Trent Potter, Roger Jones
Any recommendations contained in this
publication do not necessarily represent
GRDC policy. No person should act on the
basis of the contents of this publication,
whether as to matters of fact or opinion or
other content, without first obtaining
specific, independent professional advice
which confirms the information contained
in this publication.
The “Managing Blackleg and Sclerotinia in Canola”
Back Pocket Guide is part of a series of Back Pocket
Guides published by GRDC.
For free copies please contact:
GRDC Publications Manager
PO Box E6 Kingston, ACT 2604
Telephone: 02 6272 5525
Facsimile: 02 6271 6430
Email:
[email protected]
GRDC
Grains
Research &
Development
Corporation
POCKET GUIDE
Canola Diseases: THE BACK
Individual plants or
patches die
Phytophthora root rot, Sclerotinia stem rot
Plants infected by Phytophthora root rot, begin to die and
are easily pulled up. Infected roots show decay and a dark
discolouration. Plants can be infected individually, or in
patches which are often low-lying wet areas. Most common
on poorly drained, heavy soils.
Root decay and
discolouration caused by
Phytophthora root rot.
Sclerotinia stem rot
infection appears as white
fluffy growth on stem.
Sclerotinia stem rot appears as white fluffy growth on the stem.
Crop growth stops above this point and severely affected plants
will die and lodge. Affected area on the plant is usually greyish
white or brownish white. Black, irregular-shaped fungal fruiting
bodies (sclerotia) form on and in stems.
Favoured by warm, damp spring weather during flowering.
Black sclerotia in stems.
Blotches with black specks
Blackleg
Grey, circular spots with black fruiting bodies (specks) forming
in the centre. Lesions can appear on any part of the plant at
any growth stage, with leaf lesions occurring even on resistant
varieties. Stem canker occurs later in the season and affected
plants will lodge, producing little or no seed.
Canker on the base of stem
Leaf Lesions
Blotches with dark
margins
Alternaria leaf spot
Alternaria spots on a
canola stem.
Alternaria spots on a
canola pod.
Dark target-like round spots that commonly appear on leaves,
but can also infect stems and pods. Pods severely infected can
become covered with spots causing them to prematurely shatter
and seed to shrivel. Infection spreads with wet, humid weather
during spring. Seed from infected pods can cause seedling
blight if sown.
Alternaria spots on a canola leaf. Note the target-like
appearance and the chlorotic halo on the leaf.
Flower heads distorted
White rust
Whitish cream pustules may form on leaves, stems, flower heads
or pods. The infection distorts the flower head, causing it to
enlarge and resemble a stag’s head.
Not common in canola crops, but more common in Brassica
rapa (Turnip rape) and B. juncea (Indian mustard).
Favoured by cool, moist conditions.
Distorted flower
heads.
This guide should be used in association with the
following publications:
• Canola: The Ute Guide
• Your Guide to Growing Golden Canola, Agriculture
Western Australia
• ‘Fungal diseases of canola in Western Australia’,
Department of Agriculture, WA, Bulletin 4406.
• Canola, NSW Agriculture
• Canola Check Tool Kit, Primary Industries and Resources SA
• Canola Cache, Kondinin Group
Each state department of agriculture / primary industries also have
a series of farm notes / fact sheets on canola production which are
updated on a regular basis.
Guide concept: Ross Andrews, GRDC
Photography: Stephen Marcroft, Mark Stanley, Roger Jones,
Martin Borbetti
Text: Stephen Marcroft, Trent Potter, Roger Jones
Any recommendations contained in this
publication do not necessarily represent
GRDC policy. No person should act on the
basis of the contents of this publication,
whether as to matters of fact or opinion or
other content, without first obtaining
specific, independent professional advice
which confirms the information contained
in this publication.
The “Managing Blackleg and Sclerotinia in Canola”
Back Pocket Guide is part of a series of Back Pocket
Guides published by GRDC.
For free copies please contact:
GRDC Publications Manager
PO Box E6 Kingston, ACT 2604
Telephone: 02 6272 5525
Facsimile: 02 6271 6430
Email:
[email protected]
GRDC
Grains
Research &
Development
Corporation
POCKET GUIDE
Canola Diseases: THE BACK