A perfect storm of unfavourable climatic conditions during fruit set and fruit development was responsible for the disastrous splitting of Navel oranges evident this season in the Eastern and Western Cape, says Hannes Bester of Citrus Research International, following an investigation into the phenomenon.
Navel growers in the Eastern and Western Cape expect losses of between 30 and 50%, if not more in some areas.
“There were temperatures of over 40°C with very low relative humidity of 7 or 8%, coupled with warm and high wind speeds, which all drew moisture from the flowers and fruit. This occurred during early cell division and as the fruit increased in size during subsequent cell enlargement, the rind split open.”
Furthermore, navel ends are particularly large this year, a common tendency under very high temperatures, and this exerted more pressure on the rind.
“Last year we saw the same phenomenon on fruit in the Karino area, outside Nelspruit, and this year it’s in the Eastern Cape, particularly the Sundays River Valley, and to a lesser extent in the Western Cape.”
“We’re always busy with research on how plants could be assisted to put up more resistance to stress conditions. There’s never a silver bullet but a combination of factors, like hormone treatments and more effective irrigation methods and other products under evaluation can be employed to ameliorate the effect of such conditions on plants,” says Bester.
