What are the marks on my Bramleys?
Q Why is the flesh of my stored ‘Bramley’ apples spotted brown?
Alan Carter, Garsington, Oxfordshire
A The first symptoms of this disorder, known as bitter pit, are dark spots underneath the skin, which later show on the surface as slightly sunken pits. Small, brown areas of tissue develop immediately beneath the pits and are scattered throughout the flesh of an affected apple.
Calcium deficiency and/or excessive amounts of potassium or magnesium within the fruits cause this condition. It’s not necessarily due to a lack of calcium in the soil, as it can occur on trees growing in highly calcareous areas on chalk or limestone. Bitter pit appears to be connected with a shortage of water at critical times in apple tree growth and is worse in seasons when there are wide fluctuations in rainfall and temperature. Mulch trees well and water the soil in dry periods before it dries out completely. Bitter pit can be reduced by spraying trees with calcium nitrate, starting in mid-June, applied at the rates and intervals given by the manufacturer. It’s available from Garden Direct (0845 217 0788; www.gardendirect.co.uk). The solution should contain a wetting agent such as soft soap, or a few drops of a mild liquid detergent, to allow the calcium to stick to the leaves.
Continue applications until mid-September, spraying in the evening to avoid russeting of the skin. If temperatures exceed 21C (70C) either refrain from spraying or use the chemical at half-strength.
‘Crispin’ and ‘Discovery’, which are sensitive to calcium nitrate, should not be sprayed but they’re not particularly susceptible to bitter pit.
The fruit of ‘Bramley’s Seedling’ can also be injured by sprays of calcium nitrate but, because it’s very susceptible, some risks may have to be taken, but spray trees with a half-strength solution. Other susceptible varieties include ‘Newton Wonder’ and ‘Merton Wonder’.
If calcium nitrate spraying isn’t feasible, for example on very tall trees, you can freeze fruit from trees with a recurrent bitter pit problem before the disorder has chance to develop.