Transcript Plant disease images

PLANT DISEASE IMAGES
Rose rust
Rusts are fungal diseases that grow on leaves. Rose rust is specific to roses, and is caused by parasitic fungi of the genus Phragmidium. The
disease begins during spring and persists until the plant’s leaves fall off. This scanning electron micrograph shows the fungus sitting on the leaf
surface.
Credit: Annie Cavanagh/Wellcome Images
Apple scab fungus
Venturia inaequalis is a fungus that causes Apple scab – a common disease of apple trees that leaves dark brown marks on leaves, buds
and fruit. Symptoms begin with light green lesions on the underside of leaves, which increase in size before turning olive-coloured and
velvety. This light micrograph shows the presence of the fungus on the plant’s surface.
Credit: Spike Walker/Wellcome Images
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Wheat rust fungus
Puccinia graminis is a fungus that can cause significant disease in cereal crops. Known as the ‘polio of agriculture’, it was once the most feared disease
of cereals. It is not as damaging today due to the development of resistant cultivars, but some strains still threaten wheat production. This light
micrograph shows a cross-section of a wheat stem with the fungus growing out of it.
Credit: Spike Walker/Wellcome Images
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Needle fungus on a grand fir
Needle fungi reproduce through spores that spread and infect other, healthy pine needles. A single conifer may contain several dozen different fungal
species. Many of these fungi are not harmful and some are even beneficial, protecting the tree against harmful insects.
Credit: Richard Droker/Flickr
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Cytospora canker
Cytospora canker is a disease that affects spruces and other conifers, caused by the fungus Leucostoma kunzei. The
disease often begins in response to wounds, drought, harsh winters or other factors that the affected tree has been
exposed to. The cankers ooze resin that resembles snow or hoar frost.
Credit: Nicholas A Tonelli/Flickr (CC BY)
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Powdery mildew on a scrub maple tree
Powdery mildew is a fungal disease that affects the foliage, stems and sometimes the flowers and fruits of plants. Many familiar edible
garden plants – including apples, blackcurrants, grapes and cucumbers – can be affected by this disease. It is caused by dampness, high
levels of humidity and the overcrowding of plants.
Credit: Diane Cordell/Flickr
Green algae on a southern magnolia leaf
Cephaleuros virescens is a species of green algae often found in tropical and subtropical regions. It afflicts magnolia, mango,
avocado, citrus and guava plants among others. It is not usually harmful to the plants it lives on, but can lower rates of
photosynthesis, harming the development of fruit.
Credit: Malcolm Manners/Flickr (CC BY)
Southern rust on a corn leaf
Rusts are commonly brought to North American corn fields by wet and windy weather conditions. Southern rust is caused
by the fungus Puccinia polysora, which thrives in high temperatures and humidity. It has a mottled orange-brown
appearance.
Credit: Scot Nelson/Flickr (CC BY)
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Wolf lichen
Letharia vulpina, or wolf lichen, grows on the branches of living and dead conifers. Its bright yellow-green colour is
caused by the vulpinic acid it contains, which is toxic to mammals and has been used to poison wolves and foxes in the
past.
Credit: Darron Birgenheier/Flickr (CC BY)
Silk button spangle galls on a British oak tree
Galls are abnormal growths produced by plants when in contact with certain external parasites. They are made of enlarged or excessive
amounts of host cells that provide shelter, food or nutrients for the parasite. These silk button spangle galls, which house the maturing
larvae of the wasp Neuroterus numismalis, are often found on British oaks.
Credit: Peter O’Connor aka anemoneprojectors/Flickr (CC BY)
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