2025 Blackspot Manager forecast released
Friday 9 May 2025
2025 Blackspot Manager forecast released
The 2025 forecast from Blackspot Manager highlights a high risk of blackspot (Ascochyta blight) for field pea crops sown in late April and early May across all regions of South Australia – see Blackspot in field peas disease forecast.
Understanding the disease risk
The current blackspot risk is based on the number of spores released from last year’s infected field pea stubble. Actual disease severity on crops will also depend on rainfall, as moisture is essential for the spores to germinate and infect new plants.
Spores are typically released with autumn and winter rains, when new crops are emerging and establishing. If these conditions occur, there is a strong chance for blackspot to develop.
- Frequent rain events will likely lead to more severe disease outbreaks.
- Limited rainfall can keep the disease level low, even when spore numbers are high.
How to reduce your risk of blackspot infection
Delay sowing where possible
- In medium to high rainfall zones, delay sowing by 2 to 3 weeks after the first autumn rain to allow spore levels in the air to decline. This practice reduces the chance of early infection.
- Avoid delayed sowing in low rainfall, short season areas. Yield losses from late sowing may outweigh the benefits of disease avoidance.
Keep distance from infected stubble
- Sow field peas at least 500 metres away from last season’s field pea stubble.
- If the wind usually blows from the stubble area toward the new crop, increase this distance to 1 kilometre if possible to avoid windblown spore movement.
Consider using fungicide for higher-yielding paddocks
- Use a seed treatment that combines thiram and thiabendazole (for example: P-Pickel T or Evershield) to protect seedlings from early infection.
- Apply a foliar fungicide between the 4 and 8-node stages:
- If symptoms are visible, spray at 4 nodes.
- If no symptoms appear, you can delay spraying until 8 nodes.
- A second spray will be needed at early flowering to reduce disease spread later in the season.
- Apply fungicide before rain events for maximum effectiveness, as rainfall promotes spore dispersal.
- Avoid spraying after rain, as it is generally ineffective.
- Several fungicides are registered for blackspot control. Check labels carefully, especially for grazing restrictions.