Autumn Disease Control
Phoma and Light Leaf Spot can attack oilseed rape in the autumn and control measures should start then.
Phoma
- Phoma can reduce yields by up to 50%. It is the most costly disease in terms of yield, particularly early infections.
- Infection threshold is 10-20% of plants infected, regardless of the number of leaf spots seen.
- Early drilled crops should be checked in September. Small crops should be treated as soon as infection is seen.
- High risk conditions arise in early autumn sowings following a wet summer or early autumn weather, particularly in the presence of rape stubbles or crop debris.
Light Leaf Spot
- Light Leaf Spot can reduce oilseed rape yields by 40%. It is predominant in North and West England and in Scotland.
- The threshold for spraying at stem extension is 25% of plants infected.
- High risk conditions occur in early sown crops when there are cool and moist weather conditions. High trash or crop debris and susceptible varieties also increase the risk.
Further information on the importance of autumn disease control and the options available will be available here from May – June 2007 |