Northland feijoa orchards devastated by fungal disease

Feijoa growers are worried about the potential spread of a new fungal disease that is devastating some orchards in Northland.

A strain of the anthracnose fungal disease, called colletotrichum theobromicol, starts with a purpley black spot and spreads in wet, humid conditions.

Some orchards in Kerikeri have been badly affected by the new fungus, and at least one was unable to send any fruit to market this year.

Feijoa Growers Association president Roger Matthews said the arrival of the new strain was a concern, and it was difficult to predict if the fungus would spread.

"Growers further south are thinking that Kerikeri does have some warm, semi-tropical rainfall and humid conditions, and that might be what the fungus needs, and further south we might be protected from it," he said.

"However facing the prospect of climate change, all bets are off."

He said central to efforts to stop the spread of the fungus was to practice good orchard hygiene.

"This should be being done already, but any equipment or footwear going out of the orchard should be cleaned, clothing should be washed.

"If you have an infected orchard, you shouldn't be taking anything off the orchard in the way of fruit or plant material that could carry spores, so if you are pulling trees out - which unfortunately they have had to do - those will be destroyed." 

He said beyond that, there was not a lot that could be done.

"The problem with fungus diseases is that the spores are airborne, so they will blow in the wind."

Kerikeri grower Peter Jack has been hit hard by the disease, with his fruit too damaged to send to market. 

He told RNZ that the new strain of fungus behaved very differently from other versions of anthracnose because attacked the fruit before it was ready.

He said he knew of three other orchards who had also been affected, and said other growers further down the country should be worried.

"If they're not, they certainly should be. With an insect you can kill it but with a fungus it's way more difficult."