Impacts of climate change on horticulture

Depending on the farm location, climate change could affect the horticultural industry through:

• increased crop water needs
• reduced water availability
• greater crop damage due to frosts and heat stress
• increased pest and disease activity
• increased damage from extreme weather events, and
• changing production regions (where the crops grow) or cropping cycles.

Changing temperatures

Each crop has a 'coping range', the temperature range from minimum to maximum within which a crop will survive. What kind of impacts might occur when a crop is planted outside this range?

• Hazelnuts require 1200 hours of chilling at 5 to 7°C. If they experience < -5°C at flowering, the crop will be damaged.
• The quality and weight of the macadamia nut harvest is ideal when daily maximum temperatures are between 30 and 35°C from December through to February. Conditions outside this range result in a loss of production.
• Similarly, citrus fruits suffer a production loss when temperatures over 37^oC are experienced.¹

Irrigated crops

Approximately 75% of the fruit and 83% of vegetables and grapes are grown under irrigation, and these crops will likely be impacted by water shortages in the future.

Viticulture: multiple impacts

The largest horticultural crop in NSW is grapes for wine production (the viticulture industry). Specific impacts on this industry include:

• a reduction in the total number of grapes produced
• grape maturity occurring earlier in the season
• severe leaf and bunch stress.

Variable climate conditions in future mean that the cropping calendar is likely to change, particularly with earlier harvesting in a warmer climate. It would seem that the temperature of the ripening period in some regions will become too warm to produce balanced (good tasting) wines from some or possibly all grape varieties.²

Queensland fruit fly

The Queensland fruit fly has acclimatised to the horticultural production areas of inland NSW. Increased average temperatures and the way the trees respond to those changes would expand the range of the Queensland fruit fly and accelerate the expansion of a wider range of other tropical fruit fly species.

 

 

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¹Fairweather H & Cowie A, 'Climate change research priorities for NSW primary industries', Discussion paper, NSW Department of Primary Industries, Orange NSW, 2007.

²'Climate Change - Impacts & adaptation in Lower Murray-Darling. Viticulture: developing industry preparedness', Gregory Moulds, Viticulturalist, NSW Department of Primary Industries, presented at Buronga Climate Change Forum.