Story: Citrus, berries, exotic fruit and nuts
Page 5 – Boysenberries and raspberries
Boysenberries (Rubus hybrid) grow on a type of bramble. They are of hybrid origin, although their exact parentage is unknown. Boysenberries were introduced to New Zealand from Knott’s Berry Farm, California, in the mid-1930s.
They are deciduous plants. Canes grow during the first summer and fruit in the second, after which they are pruned out. Boysenberry canes have a rambling growth form, and require support.
The plant produces large, flavoursome purple–black fruit, suitable for freezing, canning and jam-making. The harvest period is in summer – two to three weeks at the end of December and beginning of January. Unlike other Rubus species (which include raspberries and blackberries), they do not require winter chilling. They need deep loam soils with a pH range of 5.8–6.3. Just over 60% (151 hectares) of New Zealand’s boysenberry crop is grown in the Tasman district in the northern South Island. A further 20% (56 hectares) is grown in the North Island, in Waikato, the Bay of Plenty and Hawke’s Bay.
Early plantings succumbed to downy mildew fungus, but cultivation increased when fungicide sprays became available. In the 1980s over 600 hectares were planted, but this had dropped to about 240 hectares by 2002. During the 1980s and 1990s much of the crop became infected with a disease – boysenberry decline – that stops fruit forming.
New Zealand’s frozen export boysenberry trade was valued at NZ$4.8 million in 2006.
Red raspberries (Rubus idaeus) have been grown in New Zealand since early European settlement.
They have always been in demand for jam-making and are a popular fresh dessert fruit at Christmas. However, their cultivation in New Zealand has been a story of boom and bust.
In the early 1900s there were many raspberry growers, with over 100 around Nelson. The annual crop at the time was estimated at just over 1,000 tonnes. Production declined during the 1930s depression, and slowly recovered until 1970. Then many plants became infected with raspberry bush dwarf virus, which had been inadvertently introduced with an imported cultivar. The virus spread from plant to plant during pollination and caused leaf-yellowing and crumbly fruit.
The industry recovered during the 1980s and peaked in 1985, with 550 hectares in cultivation and 2,600 tonnes produced. At this time raspberries were New Zealand’s fifth most valuable fresh export, with Australia the main market. But in 1988 Australia stopped accepting New Zealand’s fresh raspberries as they were infected with raspberry bud moth (Heterocrossa rubophaga) – a pest insect, endemic to New Zealand.
The industry has declined since that time and by 2006 was based around 60 growers on 200 hectares. This is not enough to satisfy the domestic market, and since 1995 New Zealand has imported the berries, mainly from Chile.