Phytophthora crown rot

1. 01Stunting, or wilting of young leaves, at any point in the season
2. 02Collapse of the plant with a deep dark red discolouration of the crown
3. 03Drought-like leaf symptoms: browning margins moving between the veins, with a sharp line between damaged and healthy tissue
4. 04Cut the crown lengthways and the inside is a red or reddish dark-brown spongy rot

Poorly drained or over-irrigated soil, and long periods of rain in warm climates. It is a water-driven disease before it is anything else.

Kills plants outright. Losses are permanent gaps in the bed.

• Fix drainage first — raised beds, and land that sheds water rather than holding it
• Stop over-irrigating; this is the most common contributing error
• Use clean planting material and avoid replanting into ground with a history
• Cut open a few collapsed crowns before assuming it is something else — the diagnosis is free

Spray strategy. Cultural and drainage measures carry most of the control. Chemical options exist but will not compensate for a wet site.

• Winter Dawn

  Carries resistance to Colletotrichum crown rot — a different crown pathogen, but relevant when diagnosing crown collapse