How horticulture is adapting to climate change in this region

Case study - Mango growers Gingin/Dandaragan

Horticulture in the West Midlands

Background• Horticulture is moving north away from

urban sprawl to cheaper land

• Major aquifer below the sandplain

• Horticulture need lots of water

Fruit 10 000 m3/ha/year

Intensive Veges 18 000 m3/ha/year

Winter potato crop 4 000 m3/ha/year

Crops• Citrus, stone fruit, mangoes, potatoes, grapes, almonds,

wildflowers

• Range of crops with a wide range of climatic requirements

Existing climate challenges for this area

• Very hot days in summer not ideal

Plants shut down, Sunburn

• Wind rub on fruit/damage to plants

Consumers buy appearance wind rub/sunburn

Eating quality ok but seconds lower price

• Frost on sensitive species

• Insufficient winter chill on stone fruit and almonds

• Closer to coast moderating influence of ocean and sea breezes

Risk assessment for horticulture to Climate Change (for RCP 8.5 climate scenario)

Risk Priority

Extreme weather events reduce quality of fruit and vegetables or cause the crop to be unmarketable High

Less rainfall results in less ground water for irrigation High

Decreased rainfall causes an increase in irrigation water salinity Medium

Sunburn on fruit

Frost damage of citrus

Groundwater recharge with climate change

• General rule of thumb

• 10% reduction in rainfall = 20% reduction in recharge

• If rainfall decreases by 15 % then recharge will decrease by about 30%

• Dept. of Water are currently reviewing groundwater allocation plans. There will likely be reductions in allocations to balance competitors needs.

Risks:

Primary

Industries

Adaptation Actions

a) Extreme

weather

events

reduce

quality of

fruit and

vegetables

1. Use management practices to allow current crops/varieties to be grown successfully e.g. canopy management, protected environment & greenhouses, don’t grow heat intolerant vegetable crops in summer.

2. Develop alternative crops/varieties for changed conditions. Manage risks by diversification where possible.

3. Move production to the south west of the state. b) Less

rainfall

results in

less water

for

irrigation

1. Increase water use efficiency by improving irrigation design and scheduling. Change to micro irrigation.

2. Move to other areas with more available irrigation water

3. Grow higher value crops or crops which have lower irrigation requirements.

4. Trading of water will result in water moving to higher value activities such as horticulture.

Possible actions by horticulture to overcome climate change

Case study Mango growers in the Gingin/Dandaragan Area adapting to climate change

There are two main climate issues for mango growers in south west WA

1. Cool temperatures at flowering reducing fruit set and yield in some years.

2. Sunburn damage of mangoes results in up to 50% loss of marketable fruit in some years.

Observations by mango growers

•Earlier flowering. Now occurring in August/ September when temperature are often too low for good pollination

•Earlier harvests February not March

•Increased sun burn from very hot summer days

Can delaying flowering increase yield?

1. Burning off the flowers with herbicide to allow secondary flowering to occur in a more favourable climatic window.

2. Sprayed trees with GA in mid July to delay flowering.

Effect of GA sprayed in mid July

Protected cropping trial

Variety selection

Is Kensington Pride the best variety for south west WA?

Want a variety that flowers in correct climate window in all years

Graft over trial trees with varieties with a later flowering

Irrigate more efficiently

Design irrigation systems that apply water more uniformly.

Trade off between cost of infrastructure and operating costs

Schedule irrigation using weather station data not finger in the air

Use soil moisture sensors to determine when to irrigate

Water is still available and free except for pumping costs. Greater water use efficiency will occur in the future when water becomes more limiting.

Hills stone fruit/almonds

Chilling requirementDormancy breakersVariety selectionSite selection

Micro climate significant

Summary

Range of horticultural crops and range of climate issues

High value crops more scope for intervention?

Much more costly if you get it wrong

Trialling new approaches

• Tree manipulation• Protected cropping• New varieties

• Irrigation efficiency