Crunch time for pests
THE term codlings was used in medieval times to describe small, undeveloped, plum- sized apples. Most apples will have achieved this size by late spring and that’s when the fi rst signs of attack from codling moth grubs begin to appear.
Any neglected apple trees that carried grub- infested fruit last summer are certain to be attacked again – and even more severely unless control measures are taken.
There’s no point waiting for the fi rst apples to be attacked, because once grubs have penetrated an apple they remain completely protected from predators and sprays.
So, in order to obtain some kind of control, it is essential to start now.
The fully fed grubs that emerged from apples last summer found a place to hide over winter in cocoons, either in crevices in the trunk, under loose, fl aky bark or even between nearby fence or shed palings.
At the moment many are already emerging and preparing to change into codling moths. This happens when daytime temperatures start to remain fairly steady at around 21C.
Female moths don’t fl y much, they usually remain in the same tree, hopping and fl uttering at the end of a warm, sunny day.
They give off a special scent to attract male codling moths from elsewhere, while newly formed males fl y off to other vulnerable fruit trees.
After copulation, the females soon begin producing shiny, fl at, scale- like eggs which they stick on, or close to, young apples.
Pears, quinces and even walnuts are also vulnerable to codling grub attacks, but to a far lesser extent.
When the time is right, the grubs hatch and move rapidly to penetrate the nearest apple.
Some simply burrow in from the safe shelter of the scale cover, while others crawl to a withered calyx at the base of an apple and enter from there.
If you don’t start control measures now, large numbers of fruit will be showing signs of damage, even as early as Christmas.
By the end of February or early March, all the damage has been done and most grubs will have found a place to shelter through winter, ready to start the cycle again next spring.
Applying band traps, loose pieces of hessian or corrugated cardboard around the trunks of apple trees is a great help. They go on now.
However, keep in mind that they cannot protect this year’s apple crop.
These bands simply provide dry, protected places for the grubs to hide after they have eaten their way through the fruit.
This is why these bands containing the fi rst wave of skulking grubs must be removed and destroyed in late December and immediately replaced with new ones. These are removed and destroyed in March.
This is one way of reducing grub populations so less damage happens the following year.
The biggest blunder is to leave trap bands on during winter, because most are full of codling moth cocoons.
For more immediate control, female scent ( pheromone) traps are very effective.
They look like little toy houses and are hung from trees.
The scent given off lures incoming male moths to a sticky surface, where they die.
Unfertilised female moths don’t lay eggs and have a short, barren life.
One trap for every three trees seems to do the trick.
The traps also clearly indicate when moths are most active.
It also helps if the lower trunks of apple trees are given a brisk scrubbing with a stiff wire brush.
This removes fl aking bark and either kills or exposes embedded cocoons, which can be killed with a nail.
As fruit begins to develop in late November, I inspect them every few days. It’s an easy task to pick off attacked apples and place them in a bucket. This also removes feeding grubs. All fallen apples must also be collected and, by placing them in a sealed plastic bag and leaving it out in the sun, all grubs are destroyed.
This timely apple removal is also another method of thinning the fruit, because trees always produce too much.
Used in conjunction with pheromone and band traps, this has proved very effective at controlling codling moth damage.
And all without the use of poisonous sprays, so the apples are safe to eat.