What is strawberry black eye?

Strawberry flowers often open before the last frost. Black eye results when frost kills the reproductive parts of the flower, and as a result the flower will not set fruit. Partial frost damage to the flower tissues will not cause black eye symptoms, but the resulting fruit may be distorted.

Symptoms

You may see the following symptoms:

• The central, reproductive parts of flowers killed by frost turn black, while the petals remain white.
• Some flowers on a plant may remain unaffected while others show black eye symptoms.
• Flowers with black eye will not set fruit.

Biology

Strawberry flowers are relatively resistant to frost damage while they are still in tight bud. Buds that are just about to open, and particularly open flowers, are more susceptible to damage.

The amount of damage that occurs will depend on the degree of frost and the length of time for which plants are exposed to it, but also on the relative position of flowers on the plant. Flowers covered by leaves, for example, will be less susceptible than those that are fully exposed.

Even strawberry flowers under cloches or polythene can be damaged; those close to or touching the polythene or glass are most at risk.

Control

• Avoid planting strawberries in frost pockets or on exposed sites

• Protect plants in flower when frost is forecast with a temporary cover such as horticultural fleece or newspaper. Weigh this down to prevent it from blowing off the plants, and lift it during the day to allow access for pollinating insects