Guava moth hack: growing better feijoas
A lot of us are getting it wrong when it comes to netting our feijoa trees against the insidious guava moth.
New Zealand Feijoa Growers Association chairman Roger Matthews says we need to be tying our nets off tight around the trunk instead of just draping them over the trees, which is the habit of many backyard growers.
“The guava moth grubs live in the soil and they fly up and lay their eggs on the trees,” says Matthews, who grows 1100 trees of his preferred Anatoki, Kakariki and Wiki Tu varieties at his Morrinsville orchard.
“And your highest concentration of guava moth will be directly under the tree, so if any of that soil is exposed inside your net, your system is going to fail.”
The grubs burrow into the fruit and slowly mature.
When the fruit falls onto the ground, the grubs come out of the feijoa into the soil where they pupate over winter, says Matthews.
The moths’ life-cycle makes them difficult to spray because the spray can’t reach them when they are in the soil or fruit.
“So the only hope is when they’re on the wing, and you’ve got these things hatching every day all through summer,” Matthews says.
“You’d pretty much have to spray them daily and then you’ll have pretty big residuals sitting on your fruit surface,” says Matthews, who got into feijoa growing because he wanted to grow fruit without using chemical sprays.
“You definitely don’t want to be using a pesticide that’s systemic and is going to poison the fruit itself,” he says.
“Plant & Food did the research and basically drew a blank on chemical controls.”
And for all those gardeners who favour organic pesticides such as Neem, Matthews just rolls his eyes. Neem doesn’t work, he says, and it’s toxic.
The chemical compound Azadirachtin A found in Neem has been classified as an eye irritant, causes an allergic reaction on skin and is very toxic to fish, Environmental Protection Authority NZ says. In fact, Neem oil is banned in the
United Kingdom and is not registered for use as a pesticide in Canada.
“One strategy that I think is going to see you right far better than Neem is chickens,” Matthews says. “Chickens will be into the grub in the soil and they’ll be into them as they start to emerge and they’ll also peck open fruit. Chickens are quite good.”
Research has also found that guava moths have yet to make it past the Bombay Hills.
“We put traps all over the country and found nothing south of the Bombay Hills,” Matthews says. Some were found in Miranda, around the Firth of Thames, and Cooks Beach, Whitianga. Then Matthews did further testing on behalf of the Feijoa Growers Association.
“I got the fancy lures from Plant
& Food Research and ran a trapping campaign in a triangle from Ōhinewai in the north to Whatawhata in the west and in Morrinsville on my orchard in the east. We trapped that for three years and didn’t catch a single moth.”
And the crop is becoming more popular in the South Island, he says, where early varieties such as Anatoki, Gemini, Kaiteri, Kakariki, Pounamu and Unique fruit are best suited to beat the first frosts.