Adaptions to the impacts of climate change can be assessed on different scales, tactical, strategic and transformational. The horticulture industry is renowned for being nimble and able to make transformational change in response to economic opportunities.
The tactical adaptions for the three fruit crops are related to plant husbandry techniques. Modification to the current system and practices relating to the types of chemicals used, pruning regimes or irrigation are suggested for managing the changing climate. In particular, summer vegetative growth can be controlled to favour reproductive growth by:
Winter pruning: The balance of number and types of buds can be changed to increase reproduction growth in the next growing season. Also for vines, selecting thinner canes will reduce summer vegetative growth.
Summer pruning: Grape vines are mechanically pruned and Kiwifruit cranes are pruned to back to the last fruit on the shoot to suppress vegetative growth. Although a second pruning in summer creates additional labour costs these practices may be required more in the future.
Girdling vines: Kiwifruit vines are girdled (ring-barked) to prevent the flow of carbohydrates from the canopy to the roots. The disruption makes the fruit more competitive in the allocation of carbohydrate within the plant for the short time the girdle is open. Girdling techniques may be considered for the management of vegetation growth in other woody fruit crops in the future.
The risk of sunburnt fruit from extreme high temperatures events might be reduced by pruning in the winter to encourage more vegetative growth to provide shade for the fruit. However this tactic is counter to the tactics considered for reducing summer vegetative growth. Flower and fruit thinning can be carried out in favour of shaded positions on the trees and vines.
Investment in new infrastructure or cultivars involves a greater level of managerial adjustment, decision making, planning and resources.
The strategic adaptions suggested tend to be directed towards managing extreme weather events. The use of multi-purpose overhead netting protects against a range of risks including sunburnt fruit and also damage from frost and hail. The installation of overhead netting is already occurring and is more likely to be needed in the future. More shelter may be needed to protect against strong winds. Even though fewer frost events are anticipated overhead sprinklers may be employed to manage late frosts which impact on the growing season.
Irrigation needs and the installation of new infrastructure are likely to increase in the future but actual degree of change is still uncertain. New irrigation schemes are being mooted around New Zealand, particularly in the eastern and northern regions. Water storage is proposed for irrigation water in the Central Hawkes Bay, Wairarapa and North Canterbury.
Significant changes to business might occur if the existing crops become unviable in the future. Businesses might be compelled to introduce new crops on the same land or the business might relocate to another region to grow the same crop.
Examples of land-use change already exist, such as in Marlborough, where viticulture became the dominant industry on land which was previously used for dry stock farming. This kind of shift in land use is predicted in the future. New horticulture areas may include areas such as the Mamaku Plateau near Rotorua, the Ruataniwha basin in the central Hawke’s Bay in the North Island or the Hakatrarmea and Maniototo valleys in the South Island.