Dandelion Leaves

Dandelion Leaves

Observation - Dandelion Leaves - UK and Ireland. Description: The leaf tips in a whole zone are purpled and shrivelled, turned downwards and eventually browning.

The leaf tips in a whole zone are purpled and shrivelled, turned downwards and eventually browning.
There are no distinct aphids, midge punctures or fungal shapes.
What might it be?
Most of the field is not affected, the leaves are mature, bright green, erect and healthy