BER is caused by too little calcium in the bottom tissue of young, developing fruit. Usually BER occurs in plants grown under conditions that a) either reduce the transport of calcium to young fruit, or b) accelerate fruit growth.
Applying gypsum or calcium containing fertilizers to the soil may help to prevent BER in some cases, but this is generally ineffective. Spraying calcium onto plant leaves and stems seems to be another solution, however calcium is not absorbed by the outer layers of plant tissue as desired. Furthermore, calcium does not move well from leaves to fruit. Thus, in order to be effective, calcium sprays would need to be applied weekly and directly onto young, developing fruit.
To minimize damage from this disorder:
- Choose cultivars with smaller fruit, as they are less likely to suffer from BER.
- Avoid flowering during hot weather, by sowing or transplanting earlier or later during the growing season.
- Before sowing or transplanting, ensure that the soil is not acidic or alkaline, or contains low levels of boron (B), as this disrupts the uptake of calcium by plant roots.
- Do not over-fertilize with nitrogen rich fertilizers, especially after flowering has started.
- Irrigate flowering and fruiting plants regularly and with appropriate amounts of water. Mulching helps to keep soil water levels constant.
- Ensure that roots are not damaged. Control nematodes, a soil-borne pest that destroys a plant's finer roots, through proper crop rotation.
- Fruit showing advanced symptoms (Figure 2) slows down the development of other fruit, so these should be remove as soon as possible.
