The organic fight against fruit fly and codling moth

There are three little beasties that frighten us as we attempt to grow our produce using biodynamic and organic means, they are the Queensland Fruit Fly, the Mediterranean Fruit Fly and the Coddling Moth.

While a lot of species have been introduced into Australian and find a niche in which to wreak havoc, the Queensland Fruit Fly is one of those native species that have flourished with the introduction of fruit by settlers. And the tricky thing about it and its cousin, the Mediterranean Fruit Fly, they have an annoying ability to infest fruit without you quite realising it.

As for Coddling Moth, these annoying critters not only affect fruit ripening on the tree but also find their way into our pantries. Making short work of poorly stored grains, flours and other dried goods.

I have a healthy respect for these little creatures. They are opportunistic and tough as hell. Keeping them at bay is a constant effort on our part. If you’re not careful, they can overrun your crop in what feels like a matter of days!

An old joke I was told as a child still rings true … “What’s worse than finding a worm in your apple?” Why half a worm of course! And this is true. So how do we keep our fruit and veggies clear of these three debilitating insects? By carefully monitoring their activity and infestation.

I will admit, that due to the amazingly wet Summer we have had this year, I was cheering about not having to water too often. I expected our zucchini to suffer some water damage and fungus … but that isn’t too hard to combat as they grow like weeds here! Some fruit swelling was also expected in the tomatoes and cherries, but I did not anticipate the rate at which the Fruit Fly have spread through our crops!

What’s the big deal? You may ask. Fruit Fly and coddling moth larvae eat the flesh of fruit to grow. The adult fly pierces the flesh of the target fruit whereas the adult moth lays an egg (usually on the trunk or branch of a tree) from where the caterpillar crawls to the target fruit. Once the larvae hatch, the decimate the fruit. Turning it into an unusable mess. They have a relatively short growing cycle and are only treatable during the early stages of growth.

Most commercial growers use strong pesticides which require a “withholding” period before fruit consumption. This means that the fruit is not fit to eat within a certain number of days after the chemical has been used. These chemicals are generally absorbed into the flesh of the fruit and kill the young larvae within. It is these chemicals which we avoid … but sometimes I wish to use them.

Other chemicals work on the adults. For fruit fly, there are a number of bait and trap methods available. These are non invasive and do not effect the fruit or require a withholding period. We use these methods in our crops … but this wet season has taught us a valuable lesson … every day that it rains, check and potentially re-apply the baits!

In the early AM, I will be destroying wheelbarrow loads of fruit because we were not diligent enough.  😦  A sad fact I know …. but on the bright side, the chickens will have a great feed!

Here is what the infected fruit look like just off the vine. You can see the discolouration just under the skin showing indications of larvae damage.

Inside, the fruit is a pulpy mess. You can see a couple of the white large in this image.

It’s heartbreaking to have to destroy part of a crop … but if we did not, all our fruit would be affected.

So the fight against fruit fly continues this season. Codling moth is mostly affecting our pears ATM … but we shall see how they fair in the ripening months ahead. Weekly baiting and dusting of our crops continue, but we are now ready for the next rains.

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