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Fungal disease
Leaf scorch
Diplocarpon earlianum
Looks like common leaf spot early on, and is routinely mistaken for it. The difference is the centre of the spot.
What you see
- 01Irregular dark purple spots scattered over the upper leaf surface
- 02Spots enlarging until they resemble drops of tar — these are accumulations of black fruiting bodies
- 03Spot centres stay purple, with no well-defined border — in common leaf spot the centres go white
- 04Leaves eventually brown, dry and curl at the margins, giving the scorched look
What brings it on
Warm, wet weather and extended leaf wetness.
Why it costs money
Heavy infection reduces photosynthetic area and weakens plants going into the picking window.
What to do
- Confirm which of the two you have before deciding anything — purple centres and tar-like spots mean scorch, white centres mean common leaf spot
- Improve air movement and avoid prolonged leaf wetness
- Remove badly affected old leaves
Spray strategy. Act when a meaningful share of the canopy is affected rather than on first spotting. Rotate modes of action.
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