Now the smoke haze is gone and the air is clear after the rains, sunburn is a real risk to apples and pears.
Under cloudy and hazy conditions, the fruit's natural cuticle is less developed, so when skies clear the bright sunlight with strong UV radiation can have devastating effects.
There are three types of sunburn: photo-oxidative, browning and necrosis (Figure 1).
•Photo-oxidative sunburn is when fruit is suddenly exposed to sunlight and UV radiation. Causes are summer pruning, late thinning and sudden exposure.
•Sunburn browning occurs when the temperature of the skin rises to 45C–48C for 60 minutes.
•Sunburn necrosis is when the fruit skin temperature rises to 52C for at least 10 minutes.
The skin temperature of fruit is regularly above air temperature by at least 11C. When air temperatures get to 32C, sunburn browning is a potential problem.
Parka augments cuticle’s protective system
Parka supplements the natural fruit cuticle helping to protect the fruit from photo-oxidative sunburn and sunburn browning.
A clear supplement, Parka has no residue or removal problems, but effective in augmenting the natural cuticle’s protective system.
For contact details, see Tree Fruit Jan 2020
