Markus Varesvuo / Garden warbler (Sylvia borin) perched on twig covered in Willow (Salix sp) pollen causing yellowing of feathers, Uto, Finland, May.

Nigel Cattlin / Heart rot (Phytophthora nicotianae var. parasitica) yellowing discolouration symptoms and dead growing point in young Pineapple (Ananas comosus) plant, South Africa.

Nigel Cattlin / Yellowing leaves of a Capsicum pepper (Capsicum annuum) plant with iron defficiency in a greenhouse, Berkshire, UK, August.

Nigel Cattlin / Necrosis and chlorosis on potato leaflets, a symptom of magnesium deficiency in a garden crop, Berkshire, UK, July.

Nigel Cattlin / Interveinal chlorosis a symptom of manganese deficiency on an apple leaf

Nigel Cattlin / Two-spotted spider mite (Tetranychus urticae) bronzing effect of grazing damage by mites on grapevine leaves, Champagne Region, France,

Nigel Cattlin / Focus (patch) infection of damage by a root knot nematode (Meloidogyne incognita) in a soybean crop, Florida, USA

Nigel Cattlin / Sugar beet virus yellows (BYV) chlorosis symptoms on a sugar beet leaf in a maturing crop, Greece

Nigel Cattlin / Chlorosis on stinging nettles (Urtica diocia) caused by glyphosate weedkiller in the early stages of weed control after spraying. Treatment weakens the plant and gets drawn into the root system, Berks...

Nigel Cattlin / Early chlorosis on stinging nettles caused by glyphosate weedkillerafter spraying. Treatment weakens the plant and gets drawn into the root system

Nigel Cattlin / Severe symptoms, chlorosis and necrosis, caused by magnesium deficiency on the edge of an oilseed rape leaf

Linda Pitkin / Yellowing curtain crust (Stereum subtomentosum), Naphill Common (SSSI), Buckinghamshire, England, November.