Tuesday, 09 October 2012 09:19

War on moth

Written by 

Now is the time to take other steps to protect fruit crops from Northland to Waikato favoured by the unwanted Aussie insect invader the guava moth, biosecurity experts say.

Guava moth (Coscinoptycha improbana) blew across the Tasman in its adult form in the late 1990s and now ruins a range of soft fruit and nuts from Northland to the Waikato year-round.

Cable Bay, Northland-based entomologist Dr Jenny Dymock, who works with the Northland Regional Council, says guava moth infests citrus including lemons, oranges, mandarins and grapefruit over the winter months.

"But by about this time of year, guava moth are also infesting loquat, which then gives the insect a big population boost heading into plum, peach and pear production over Christmas and early summer."

Dymock says because they develop within affected fruit, guava moth larvae are not easily targeted by insecticides.

"The larvae render fruit inedible with their excrement and can also lead to the development of damaging moulds and fungi. They can also cause premature fruit drop."

Dymock says experience has taught that following good orchard hygiene is one of the best ways for both home gardeners and commercial growers to try to protect their crops from the moth's larvae.

"It's important to rake up any fallen, rotting fruit and either remove it or bury it as this removes any pupae which are in the soil."

She says use of a fine weave mesh (like curtain netting) wrapped around fruit does prevent guava moth laying eggs on fruit, although realistically this is not an option for commercial growers.

"It's important not to use bird netting as guava moths can get through its broader weave. Secure your mesh by simply taping around branch of tree."

Dymock says the best time to cover fruit is just as fruit is swelling, not earlier when a tree is flowering.

And she says it's important to remember that while guava moth pheromone traps are useful for monitoring guava moth in the region, they offer little in the way of control.

"Guava moth is now too widespread through the region."

Dymock says advice about a range of insect and other pests is available from the Northland Regional Council's website via: www.nrc.govt.nz/nasties Biosecurity officers can also be contacted via the council's freephone (0800) 002 004.

More like this

Altogether Unique: Northland

Northland has had a wet and challenging season, requiring a vigilant spray programme and plenty of work to keep grass and canopies under control.

Featured

25 years on - where are they now?

To celebrate 25 years of the Hugh Williams Memorial Scholarship, Ravensdown caught up with past recipients to see where their careers have taken them, and what the future holds for the industry.

Rockit Global appoints COO

Rockit Global has appointed Ivan Angland as its new chief operating officer as it continues its growth strategy into 2025.

National

Machinery & Products

Iconic TPW Woolpress turns 50!

The company behind the iconic TPW Woolpress, which fundamentally changed the way wool is baled in Australia and New Zealand,…

» Latest Print Issues Online

The Hound

Keep it up

OPINION: The good fight against "banking wokery" continues with a draft bill to scrap the red tape forcing banks and…

We're OK!

OPINION: Despite the volatility created by the shoot-from-the-hip trade tariff 'stratefy' being deployed by the new state tenants in the…

» Connect with Rural News

» eNewsletter

Subscribe to our weekly newsletter