Intumescence

Newly formed calluses on the lower surface of a leaf (J. O'Sullivan).

Calluses, in this case clustered along the main veins on the upper leaf surface, dry up and turn brown after a few days. (J. O'Sullivan).

Diagnostic summary

• What you see on plants

- numerous small pale granular calluses scattered over the leaf surface, or clustered along the main veins.

- calluses dry up into smaller brown granules after a few days, giving the leaf surface a gritty texture.

- Occurs most frequently on young mature leaves.

- Plants in glasshouses or tissue culture develop the condition more commonly due to humid, still air.

• This is a physiological condition and is not harmful to the plant.

• Some cultivars develop intumescence much more readily than others.

Characteristics and occurrence

Symptoms

Management

References

View full fact sheet