Sunburn can be a significant cause of physical damage to deciduous fruit, particularly apples and pears.
Losses due to sunburn can be as high as 50% in some varieties and situations where protection methods are not employed.
In apples, damage is most likely when shaded air temperature exceeds 30C and fruit surface temperature is above 45C.
Poorly timed shoot and fruit thinning, pruning, or limb training can suddenly expose unconditioned fruit to direct sunlight increasing the risk of sunburn damage.
The risk of sunburn damage can be reduced by employing a range of management tools including:
•planting tolerant varieties
•timely irrigation to reduce tree stress
•avoid thinning, pruning, limb training or shoot thinning during and in the lead-up to expected heat waves
•maintenance of a green sward
•improving air flow in the orchard
•netting
•spray-on coatings.
Download the Orchard plant protection guide
See this article in Tree Fruit Dec 2019
