Wellington, Feb 14 NZPA
The vine canker spreading in the nation’s kiwifruit orchards has so far been found on 147 properties, 74 percent of them within 23km of the two orchards where the Pseudomonas syringae disease was first found near Te Puke.
Two of the strains — commonly called PSA — which affect kiwifruit have been found, and 41 of the orchards have the Italian strain which wiped out some gold kiwifruit properties in Italy over the past three years.
Another 66 properties have be shown to have a strain found in Japan and Korea, where it has been controlled over the past 15 years with antibiotics. Some industry officials have speculated that alternating sprays of copper and streptomycin may reduce build up of resistant strains.
Kiwifruit Vine Health (KVH), the industry agency using taxpayer and grower funds to battle the disease, has said that about 29ha of vines have been pulled out, and growers paid $3.6 million of the agency’s $50 million funds.
The infection appears to be spreading more quickly through gold vines and orchards, but KVH general manager John Burke said green kiwifruit orchards were not yet showing secondary symptoms such as bleeding and blackening of the vine stems.
The billion-dollar industry is due to start its harvest next month.
In Britain, researchers from Imperial College, London, have revealed this week how two genes in the bacteria Pseudomonas syringae work together to trigger infection.
The researchers hope that their gene discovery explaining how the bacteria attack plant cells will help them find new targets for pesticides and devise better strategies for disease management.
NZPA WGT kca mgr
