Exposure to high sunlight levels and heat can affect many types of fruit, vegetables, ornamental plants and even shade trees.
In apples, for example, the damage caused by sunburn not only renders the fruit undesirable, but leaves it susceptible to secondary disorders. Sudden exposure to light can cause sunburn bleaching, while a combination of heat and excess solar radiation may result in sunburn browning, commonly associated with yellow to dark brown discolouration of the peel.
In sunburn necrosis, heat damages the fruit tissue, resulting in a dark brown to black appearance and providing a substrate for spoilage pathogens.
Many types of fruit and vegetables employ biochemical mechanisms to protect themselves from excessive sunlight, but these are often inadequate to prevent cosmetic damage, which can result in financial loss. These protective mechanisms are likely to become even less effective as climate change progresses and as customers demand ever-better produce.
A proven solution
Western and Eastern Cape pome fruit farmers suffer huge financial losses from sunburn damage.
Nulandis, a South African company in the AECI group of companies, has been working with producers to alleviate these challenges through the introduction of Drape Net, which was conceived by an Australian fruit grower to negate the effects of hail in this growing region.
Drape Net Australia has been manufacturing durable, high-quality crop protection netting since 2005, testing and perfecting the netting on its own orchards.
Drape Net is now used in Australia, Chile, New Zealand, South Africa and the US as a cost-effective method to protect fruit orchards against hail as well as solar damage, reducing or even eliminating sunburn and related disorders in the fruit.
Drape nets can also function as anti-bee netting for seedless citrus crops, preventing pollination and boosting the number of seedless fruit, yet doing no harm to the bee population.
In addition, drape nets can reduce water usage. Australian research has shown that tree crops covered by Drape Net require up to 30% less irrigation in summer.
Get the timing right
Since its introduction in South Africa, Drape Net has won the support of many growers, some of whom have reported significantly less codling moth damage to their crop.
Drape nets do not require fixed structures; they are simply draped over trees like blankets and removed when no longer needed.
Correct timing is crucial and dependent on the reason for use. Where Drape Net is used to protect apples and pears from sunburn, the fruit should be golf ball-sized before the nets are erected. In Australia and elsewhere, apple growers use the nets mainly for hail protection and put them up soon after blossom set.
Drape Net is available in different colours, providing various shading factors for a range of site and cultivar combinations.
As a rule of thumb, black Drape Net should be used on hot and sunny sites with yellow and green cultivars, while white Drape Net is better for cooler sites and red or bi-coloured apple varieties.
Drape Net® is a registered trademark of Drape Net (Pty) Ltd.