At a Glance
- It is time to set your green tip date in the BC DAS Apple Scab model.
- Apple scab overwinters in infected leaf litter on the orchard floor.
- Ascospores mature around green tip, aligning with the start of new growth.
- Spores are released during rainy periods and can travel long distances.
- Primary infections occur when spores land on wet leaves, blossoms, or fruit under the right temperatures.
- The primary scab season typically peaks around blossom and ends by mid to late June.
Set Your Green Tip Date in BC DAS
It is now time to enter your green tip date in the BC DAS Apple Scab model. Setting this date aligns the infection period calculations with your orchard’s actual phenology. Use the graphs and temperature logs within the model to monitor conditions and track risk.
When Infection Begins
During rainy periods, ascospores are released and carried by air currents, sometimes over long distances. When these spores land on new leaves, blossoms, or fruit, they can cause a primary scab infection if two conditions are met:
- Temperatures are favourable
- Leaves or fruit remain wet long enough for spores to germinate
This is why infection periods are closely tied to wetness duration and temperature, both of which you can track in the BC DAS model.
How Long Primary Season Lasts
The primary scab season continues until all ascospores from last year’s leaves have been released. This timing varies from year to year but typically peaks around blossom and ends by mid to late June.
How Apple Scab Survives
Apple scab overwinters in infected leaves on the orchard floor. As temperatures rise in spring, fungal spores (ascospores) mature around the same time that new growth reaches the green tip stage. This makes green tip a key marker in the disease cycle and the starting point for monitoring infection risk.