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A pest that can have a devastating effect on fruit and nut crops is making its presence felt on the Hibiscus Coast this summer.
Keen gardeners Richard and Margaret Fowler of Manly were shocked to find Guava moth larvae had burrowed inside this season’s plum crop, making the fruit inedible.
Since they made the discovery, last month, they have found two moths as well as many caterpillars and evidence that their lemons are also infested.
The couple have heard from at least three other Coast gardeners whose fruit crops are similarly affected, and also for the first time.
One resident alerted the Ministry for Primary Industries (MPI), although the Ministry advises that there is no requirement to do this, since the pest is an established one.
Guava moth is an Australian pest that was first found in New Zealand in the late 1990s. It appears to have no specific predators in NZ and has spread throughout Northland, Auckland and into the Waikato.
It attacks many varieties of fruit and nuts, year round, including citrus, feijoas, guavas, plums, peaches and macadamia nuts.
The moth lays eggs in ripening fruit and the grub hatches and burrows into the fruit.
Generally it’s not until someone bites into a fruit that the damage is discovered. The only evidence that can be seen before this is little pin-prick holes made when the caterpillar first enters the fruit. Later the fruit becomes discoloured and you can see tiny holes where the mature grub has left.
Infested fruit is inedible due to the excrement and associated fungi and mould that build up inside. Infestation also causes premature fruit drop. In most cases, the whole crop must be destroyed.
Richard and Margaret’s lush garden is cared for without toxic sprays and Richard is fighting the pest using a homemade trap that uses an inexpensive solar powered light to attract the moths. The moths fall into a jar below which is filled with cooking oil – the trap was inspired by one designed by Northland retired teacher Harvey Gad.
Richard has also picked his plums while they’re still green to artificially ripen them indoors, but estimates that 90 percent of his crop is gone.
He says his main concern is what will happen to the country’s commercial growers and whether systemic sprays are being used to kill the pest, which could be a concern for consumers.
A spokesperson for MPI says that potentially large populations of the pest can build up in an area.
“The best control is good orchard and garden hygiene,” the spokesperson says. “Rake up any fallen, rotting fruit and either remove it or bury it as this removes any pupae which are in the soil. In addition, wrapping fruit you wish to protect with a fine weave mesh (like curtain netting) can prevent guava moth laying eggs on fruit, although realistically this is not an option for commercial growers.”
