Phosphorous deficiency

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Bright autumn-leaf colours on older leaves and stress-induced flowering (J. O'Sullivan). 


Purpling and yellowing  of older leaves while young leaves are dark green, in a severely stunted plant (J. O'Sullivan).

Diagnostic summary

  • What you see on plants

- older leaves turn yellow and then necrotic in irregular, often asymetrical patterns.


- older leaves often develop red pigment, showing a range of autumnal colours (purple, red, orange) as the background changes from green to yellow.


- young leaves remain dark green.

  • Probably the most widespread nutritional problem of sweetpotato. Symptoms indicate a relatively severe deficiency - crops without symptoms may still respond significantly to phosphorus fertilisers.

  • Many volcanic and calcareous soils bind phosphorus and make it unavailable to plants.

  • On acid soils, aluminium toxicity can induce phosphorus deficiency.

Characteristics and occurrence


Confusion with other symptoms

Diagnostic tests



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