Growers fear fungus spread

Blueberry growers outside the Waikato are bracing themselves for the coming season amid fears of a new fungus disease that has infiltrated blueberry crops.

Blueberry leaf rust - found in the Waikato among rabbit eye and high bush blueberries in January - has spread to the Bay of Plenty.

A Ministry of Agriculture and Forestry (MAF) biosecurity publication said the fungal pathogen was listed as an unwanted organism in New Zealand and thought to have blown over from Australia after it could not be linked to recent importations. The report said a ministry survey showed the rust was widely distributed in Waikato and had appeared in the Bay of Plenty.

The blueberry industry exports $5 million of fresh blueberries and $1 million of frozen ones to Australia, America, Japan and other Asian countries.

In the Horowhenua, blueberry farmer Vivien Jenkins said there had been no sighting of the pest in the lower end of the North Island.

"We haven't found any sign of leaf rust among our crops and are hoping it doesn't come our way. It reduces the amount of crop you get, stops fruit growing and drops leaves so that plants will be less able to cope," Mrs Jenkins said.

MAF plants biosecurity national adviser John Randall said the windblown spores were dependent on environmental conditions to become established.

"Rust spores require moisture for germination where the fungus produces large amounts of spores. At this stage, particularly in the Waikato, the disease primarily spreads by windblown spores and they plume in the air. It's extremely difficult to control."

Spray programmes could minimise the impact but because the country had a fairly low incidence of blueberry-specific diseases there had been very little reliance on chemical control. "There is no specific product for this disease but there are fungicides which can be used," Mr Randall said.

The ministry had had a close liaison with berryfruit growers during the investigation and was working closely with HortResearch in terms of adequate spray programmes. The blueberry industry was investigating measures to manage the disease and while it wasn't a case for quarantining every visitor to infected farms, people needed to be aware that some properties might have rust.

"Just keep in mind that if you are a grower from an area that hasn't been affected, watch what you are taking home."

Blueberries New Zealand chairman Dan Peach said the industry was working closely with other rust-affected industries such as rose and poplar growers.

"We are hoping that weather conditions will be favourable for some time and that will limit the disease."

Blueberry exports

Fresh: $5 million a year

Frozen: $1 million a year

Buyers: Australia, America, Japan and other Asian countries.


- NZPA