Grape vines grown under glass can suffer from shanking, which means that individual berries within a bunch do not colour up properly, and eventually shrivel up. The affected grapes are inedible.
Shanking occurs when within a bunch of grapes, individual berries fail to develop their colour. Black grapes remain red and white grapes remain translucent. Affected grapes persist on the bunch, becoming wrinkled and eventually resemble raisins. The flavour of these grapes is unpleasantly sour and watery.
This problem generally results from a variety of growing problems. These include:
- A poor root system, usually due to waterlogging
- Soil compaction
- Poor nutrition
- Excessive pruning when in leaf
- Pest and diseases
- Spring chilling in unheated greenhouses
Some simple measure can help prevent shanking;
- Cut out the affected berries
- Ensure that the vine has adequate but not excessive watering or feeding to its root area
- Give a foliar spray feed as an instant boost
- Ensure there is adequate drainage
- Consider re-soiling the vine root area
Pay attention also to good grape vine nutrition, care and re-soiling.
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