Calcium Nutrition in Cucurbits

Outdoor cucurbits such as courgettes are high value crops, and two plantings are made each year over approximately 6,000-7,000 acres (the latest statistics from Defra show the average price for courgettes is £1.13 per kg, ( https://goo.gl/MfRmG8). A major issue courgette growers face is blossom end rot (BER), thought to be caused mainly by poor calcium (and boron) understanding and management. BER can lead to high crop losses; in wet weather growers can throw away every other fruit.

Pumpkins are also a high value crop, and the market for carving pumpkins is currently estimated at £14-£15 million per year. The AHDB FV 439 project indicated that calcium content was related to good storability, as was high dry matter content. Mineral nutrition was tested in combination with fungal treatments, however to refine field recommendations, mineral nutrition needs to be investigated separately. Boron application at the point of flower fertilisation appears to reduce fruit abortion, increasing yield. Research into whether this is the case would be valuable to both the pumpkin and courgette sectors.

For both BER and pumpkin storage, there is already a wealth of knowledge, especially in other countries where they are popular crops, such as the USA (Cornell, Tennessee and Alabama extension services have all done work on these issues). There is also work on BER in tomatoes and cucumbers, all of which could prove useful to outdoor cucurbits, but which require further research to refine recommendations for field production. By mining existing knowledge, it should be possible to get good value for money for the growers in this sector.