After losing an entire crop, around 50kg, of plums, last season to guava moth, James Welch of Gulf Harbour is fighting back and believes he has a solution.
Guava moth, which originates in Australia and was first found in NZ in the late 1990s, has made its presence felt on the Coast this year and been the subject of several stories in this paper as local gardeners lose large quantities of fruit. It attacks many varieties of fruit and nuts, all year round (see below).
In his garden, James Welch hoisted a fine white mesh (not shade cloth) that he purchased from Mitre 10 to totally cover his persimmon and fig trees.
Timing is crucial, as the mesh also prevents bees and other pollinators from getting to the tree. James covered his trees after flowering was over, but before fruit formed.
He says it’s a method that would work for any fruit trees that are only a few metres high – he used a bamboo pole with a plastic bottle over the top to lift the mesh into place. Gaps are sealed with pegs.
His persimmon tree yielded more than two dozen bug-free fruit.
In addition, guava moth is attacking vegetable gardens; James and other local gardeners have recently found the telltale signs of the pest in their homegrown zucchinis and capsicums, rendering them inedible.
James suggests placing a ring of plastic mesh around the zucchini and capsicum plants, then draping the same white mesh over it to protect them.
James is happy for any local gardeners to contact him to find out more about his methods – phone 428 1075.
More about the moth
Timing is everything when you are attacking a garden pest, so knowing a little about its lifecycle is key.
Billy Aiken of Kings Plant Barn says this is complicated for guava moth as they can breed all year round. A further issue is that little research has been done because in this moth’s native environment (Australia) it’s not considered a problem as a host of predators helps control numbers.
However, it appears that this year more research is being done, which will hopefully help provide options to tackle the problem more effectively.
What we know
The adult moths are nocturnal, and rest on tree trunks during the day. They feed and breed at night and lay their eggs on fruit just as it starts to swell. Fruit that can be infected includes guavas, feijoas, citrus, pipfruit, some stone fruit (nectarines, plums), and chillies.
Upon hatching, the larvae immediately burrow into the fruit. Currently all known larval stages feed internally, boring into the fruit. Their presence often causes the fruit to fall prematurely.
Pupation (the stage where larvae turn into adult moths) occurs within the fruit or in the leaf litter and soil around the tree.
The presence of male moths can be detected with guava pheromone traps – this alerts gardeners to the need to protect fruit. When only small numbers are caught in traps, the traps alone may be sufficient to control the problem.
If guava moths are present, cover the tree with netting such as Bug Net (see story above) or spray trees weekly as the fruit first starts to swell. There have been reports of Neem Oil or Aquaticus Bugtrol being effective as a spray. For best results spray relevant trees weekly over the period when the fruit is first starting to swell.
To avoid infestations getting worse, dispose of infected fruit carefully. People with chickens should let them browse under fruit trees and see if they will peck into infected fruit. Otherwise, bag up the fruit and keep in a sealed container until the larvae are dead.