Fruit temperature and irradiation responsible for sunburn

Bron: European Fruit Magazine No. 8 - 2020 (139)

Sunburn damage is a well-known and common phenomenon in southern Europe. For north-western Europe, however, it is relatively new and occurs less frequently. Nevertheless, during recent hot summers, many growers in north-western Europe were also unpleasantly surprised by sunburn on apples and pears. It is known that fruit temperature plays an important role in the occurrence of sunburn damage. However, direct radiation from the sun on the fruit is also an important factor at the Belgian test garden PcFruit. During a very hot day in late July 2019, fruit temperature was measured on several pear plots (see table 1). Of the fruits under a white hail net, the temperature was nite lower than the fruits outside the net. In fact, a slightly higher fruit temperature was measured under the white nets. Yet fewer pears were burnt under the white nets than outside the nets. The researchers conclude that this is because the white nets reduced direct irradiation on the fruits.

A hail net reduces direct radiation from the sun on the fruit. The photo above is at Bangels Brothers of Bangels Fruit in Montenaken. It is a plot of Magic Star apples with the Traditional Hailnet System. At Bangels, there are also some rows with milk white hail net above them.