A Northland entomologist has warned that fruit crops need to be protected from an unwanted Aussie invader - the guava moth.
Cable Bay entomologist Jenny Dymock, who assists the Northland Regional Council, said guava moth typically infests citrus, including lemons, oranges, mandarins and grapefruit over the winter months - although citrus can continue producing and providing food for the moth well into the summer period .
The insect is thought to have blown across the Tasman in its adult form in the late 1990s, and is now an established and unwelcome pest whose larvae infests and ruins a range of soft fruit and nuts, from Northland to Waikato. "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," Dr Dymock said.
She said 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."
Dr Dymock said good orchard hygiene is one of the best ways for both home gardeners and commercial growers to try to protect their crops. "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," the expert on insects said.
Use of a fine weave mesh, like curtain netting, wrapped around fruit does prevent guava moth laying eggs on fruit. She said the best time to cover fruit is just as fruit is swelling, not earlier when a tree is flowering.