Phosphorous deficiency

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

Symptoms

Confusion with other symptoms

Diagnostic tests

Management

References

View full fact sheet