1. PLANT DISEASE IMAGES

2. 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

3. Apple scab fungus BIGPICTUREEDUCATION.COM
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
BIGPICTUREEDUCATION.COM

4. Wheat rust fungus BIGPICTUREEDUCATION.COM
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
BIGPICTUREEDUCATION.COM

5. 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
BIGPICTUREEDUCATION.COM

6. Cytospora canker BIGPICTUREEDUCATION.COM
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)
BIGPICTUREEDUCATION.COM

7. 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

8. 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)

9. 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)
BIGPICTUREEDUCATION.COM

10. 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)

11. 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)
BIGPICTUREEDUCATION.COM

12. Reusing our images Images and illustrations
All images, unless otherwise indicated, are from Wellcome Images.
Contemporary images are free to use for educational purposes (they have a Creative Commons Attribution, Non-commercial, No derivatives licence). Please make sure you credit them as we have done on the site; the format is ‘Creator’s name/Wellcome Images’.
Historical images have a Creative Commons Attribution 4.0 licence: they’re free to use in any way as long as they’re credited to ‘Wellcome Library, London’.
The Flickr images that we have used in this gallery, unless otherwise stated, are available under a Creative Commons Attribution, Non-commercial, No derivatives licence.
Cartoon illustrations are © Glen McBeth. We commission Glen to produce these illustrations for ‘Big Picture’. He is happy for teachers and students to use his illustrations in a classroom setting, but for other uses, permission must be sought.
We source other images from photo libraries such as Science Photo Library, Corbis and iStock and will acknowledge in an image’s credit if this is the case. We do not hold the rights to these images, so if you would like to reproduce them, you will need to contact the photo library directly.
If you’re unsure about whether you can use or republish a piece of content, just get in touch with us at