Management of white blister
- Yellow to brown spots form on the upper leaf surface and white, round to oval blisters develop on the matching under leaf surface.
- The blisters consist of masses of white dust-like spores.
- The fungus can cause swellings on roots and stems, and distortions of flowers and leaves.
- Confined to crucifers.
Conditions for infection
- Free water (dew, fog or rain) on leaves and stems.
- Spores germinate at temperatures of 1°C - 20°C.
- The best conditions for spores to infect plants are 3 hours of leaf wetness at 20°C.
- The disease develops at temperatures ranging from 10°C - 25°C.
- Blisters take 6 to 10 days to form after infection.
Source of the disease
- Diseased plants or crops
- Volunteer crucifers
- Wild crucifers and crucifer weeds
- Wind, rain or insects disperse aerial spores
- Rain splash of spores from soil
Control white blister with a combination of management practices:
Spores need water to germinate and wet leaf surfaces to infect plants. A short, heavy watering is preferable to a long, light watering. If possible avoid night irrigation.
Maintain good air-movement in the environment to dry leaves off quickly and reduce infection. This may mean running rows in the direction of the wind and increasing plant spacing.
Maintain a balanced program of nutrition. Applications of phosphorous (P) and potassium (K) fertilisers have been shown to reduce the susceptibility of radish to white blister.
Remove sources of spores, such as volunteer radish, crucifer weeds and if possible crop debris.
No fungicides are currently registered.
Life cycle of white blister on broccoli