mmg.com.au

In January 2013, Department of Primary Industries scientist Lexie McClymont will closely monitor weather conditions, fruit temperatures and sunburn damage in netted and un-netted Royal Gala apple blocks in the Goulburn Valley to investigate how the netting works to reduce sun damage on fruit.

Dr McClymont, who is based at Tatura DPI, said it was known that shade netting reduces sun damage, even though the air temperature may not be reduced under the netting.

Direct solar radiation plays a major role in causing sunburn damage through a combination of increasing apple skin temperatures and ultra-violet radiation.

She said DPI’s aim was to have a better understanding of how all the different components of weather interact to cause sun damage.

‘‘With this information we will be able to give growers better predictions and warnings of sun damage on fruit for both current and future climate scenarios.’’

Dr McClymont said this would help prevent some of the losses that occur each year due to sun-damaged apples and pears.

‘‘Fruit are often discarded due to sun damage varying from discoloration to full-blown sunburn. Past reports from Australian and overseas pack houses suggest 10 per cent of apples are rejected in a typical season,’’ she said.

‘‘Losses are much greater when field rejections are included and in seasons that are warmer than normal. Growers in Australia estimate losses to vary from six to 30 per cent.’’

Dr McClymont said some growers have invested heavily in practices, products and infrastructure to reduce their losses. These include shade netting, evaporative cooling and spray-on products.

She said shade netting has been a popular option for both sun and hail protection, despite its high initial capital cost of about $40000/ha.

‘‘Existing netted orchards in the Goulburn Valley offer a good opportunity to learn more about how to prevent sun damage on fruit,’’ Dr McClymont said.

‘‘The DPI Victoria and Horticulture Australia are co-operating with local orchardists in this project as part of the program for understanding apple and pear production systems in a changing climate.’’