Nigel Cattlin / Downy mildew (Peronospora parasitica) mycelium and lesion on underside of Oilseed rape (Brassica napus napus) leaf.

Charlie Summers / Pink salmon (Oncorhynchus gorbuscha) infected with Saprolegnia fungus during annual spawning run in Misty Fjord National Monument, Alaska. August.

Nigel Cattlin / Downy mildew (Pseudoperonospora cubensis), a water mould, causing lesions on the leaf of a Cucumber plant (Cucumis sp.), Greece, Europe.

Nigel Cattlin / Damping off disease caused by pathogen (Pythium ultimum) damage to maize, corn or sweetcorn seedling.

Nigel Cattlin / Pythium blight / Grease spot (Pythium spp.) damage to Bluegrass ( Poa sp.) on lawn, USA.

Nigel Cattlin / Downy mildew (Peronosclerospora sorghi) infection symptoms on the upper leaves of Maize / Corn (Zea mays) plant, USA.

Nigel Cattlin / Witch's or witches' broom (Taphrina betulina) deformed clumps of twigs on Silver birch tree in winter, Berkshire, February

Nigel Cattlin / White rust (Wilsoniana bliti) blisters on the upper surface of amaranth / pigweed leaves (Amaranthus retroflexus), Berkshire, England, UK. July

Nigel Cattlin / White rust (Wilsoniana bliti) blisters on the upper surface of amaranth / pigweed leaves (Amaranthus retroflexus), Berkshire, July