Top 7 tips for aphid control

Have you seen any leaves like this on your tree? If you have—you’re not alone. It’s a classic sign that you might have aphids, and many of our Grow Great Fruit members are reporting high aphid numbers this year.

Leaves on a plum tree showing classic signs of aphid infestation
Leaves on a plum tree showing classic signs of aphid infestation

The curly leaves on these plum trees are the typical response to the sap-sucking aphids taking up residence on the inside of the leaves. It’s different to the Leaf curl disease that you sometimes see on peach and nectarine trees.

If you tease open one of the leaves you’ll usually find aphids of some sort on the inside.

If you get a really bad infestation, there’s no mistaking it because you’ll be able to see hundreds (or thousands) of aphids crawling around, as you can see on this peach tree.

Black aphid infestation on a peach tree
Black aphid infestation on a peach tree

These are black aphids, which are one of the more common types that infest fruit trees, and will usually be seen on cherry, plum, peach and nectarine trees.

Another common type on apple trees is called woolly aphid, for a very good reason:

Woolly aphid on an apple tree
Woolly aphid on an apple tree

There’s a third type of aphid that commonly affects fruit trees, and that’s green peach aphid, which — you guessed it — you’ll find on peach and nectarine trees.

Green peach aphid infestation on a nectarine tree
Green peach aphid infestation on a nectarine tree

Sometimes when you look inside a curly leaf to see if aphids are responsible, you might see something like this instead:

There’s only a couple of live aphids here, but those small black smudges are a really good sign, as they are the dried and shrivelled remains of aphids that have been killed by other insects – “beneficial” insects that do a wonderful job of keeping pest insects under control in healthy, biodiverse gardens.

Inside this leaf is a little community of insects that is a great sign of a healthy ecosystem. A spider, and an aphid-eating wasp are co-habiting and both eating their fill of aphids (or the spider might be eating the wasp – you can never be sure who’s eating who in the insect world!)

We’re often asked how to get rid of aphids, and unfortunately people aren’t usually very happy with the answer!

Biodiversity and patience really are the keys to getting the populations of these pesky pests back under control.

Whatever you do, DON’T SPRAY INSECTICIDE! It can feel like an easy solution, but you’ll inevitably kill predator insects and just make the problem worse. In most commercial orchards, aphid populations are high – and stay high, year after year, due to the use of insecticides that routinely kill the “good” insects that would naturally keep the aphids under control.

It’s expensive, it’s ineffective, and it’s bad for the health of the tree, the user, the eater of the fruit, and the whole ecosystem.

There are a number of home-made remedies that can help in the short term with aphid control, but our experience has shown over many years that similar to bought insecticides, if you rely solely on a solution in a bottle you quickly become dependent on needing to use the same solution every year, and in fact you can be making the problem build up over time.

So, here’s our top 7 tips for getting rid of aphids:

  1. Monitor your trees regularly, particularly checking inside any leaves that have curled up, so you actually know whether or not you have aphids.
  2. If you identify that you do have aphids, watch very carefully to see whether you also have any predator insects around that are eating them – spiders, ladybirds and wasps are all particularly voracious aphid-eaters.
  3. Check whether you have ants in the tree associated with the aphids. Ants like to ‘farm’ aphids by moving them from tree to tree and guarding them from predators.
  4. If you find ants in your trees, exclude them by any means necessary. Don’t bother trying to kill the ants as they bring excellent eco-services to your garden and are very hard to get rid of, but stop them getting to the aphids by putting sticky tape around the tree between the aphids and the ant nest.
  5. Focus on building the biodiversity of plant life under your fruit trees. Flowering plants, particularly white and yellow flowers are really good at attracting predator insects and providing them with habitat.
  6. Unhealthy trees will attract more aphids, so concentrate on improving the health of your tree by improving the soil it’s growing in.
  7. Use short term solutions (like organic sprays) only in extreme circumstances, and with extreme caution!

We recommend taking a more long term view by creating such a healthy garden that aphid populations are kept under control naturally.

Having said that, short-term solutions can have their place and are part of the “toolbox” of solutions in the Aphid Management Plan you’ll find in our Protect Fruit Trees from Pesky Pests short course.

Rude fruit

Have you seen any double fruit in your fruit trees?

A double cherry
A double cherry

It’s relatively common to see double fruit (like these cherries), and as you can see, in many cases the fruit is still perfectly usable.

The photo below shows a particularly unusual one that has caused the stem to split, but doubles – or conjoined fruit – are not an uncommon occurrence, particularly in stone fruit.

Conjoined apricots with a single stem
Conjoined apricots with a single stem

Some varieties (like Angelina) seem particularly prone to this, and are often a good demonstration of the phenomenon where one piece of fruit dominates the other and ends up much larger.

Conjoined Angelina plums where one plum is much bigger than the other
Conjoined Angelina plums where one plum is much bigger than the other

In many cases one of the pieces of fruit ends up so small as to really be un-usable, or the skin of the fruits are torn when separating them, which of course downgrades the quality of the fruit.

A rude Angelina
A rude Angelina

And sometimes the extra piece of fruit is so small as to be insignificant, and sometimes can be removed without doing damage to the main fruit. But they’re also often cute, funny or downright rude, so why would you?

So, what causes this, and is it avoidable?

Whether a fruit will be double or not is determined the summer before, when the fruit buds are developing.

If the young buds go through heat or water stress during the summer months, this increases the development of doubled fruit.

There’s not much we can do about heat waves, particularly with climate change affecting our environment so quickly, but we can make sure our trees are adequately irrigated, particularly during a heat wave, to minimise the stress on the tree.

Irregular or inadequate watering can also be one of the causes for fruit splitting, which is another whole story but can look like this.

A green nectarine with a split in it, possibly caused by irregular waterin
A green nectarine with a split in it, possibly caused by irregular watering

In a home garden it’s not terribly important whether you have double fruit or not because it’s usually still usable, but it’s not as pretty, and now you know how to avoid it! Download Smart Irrigation for Fruit Trees for more tips about how to irrigate wisely without wasting water or money.

While you’re thinning…

It’s the time of year to start thinning your apricots, peaches, nectarines and plums (too early for apples and pears in our part of the world yet). We’ve explained the basics of thinning here.

Apart from the four main reasons you should be thinning all your fruit trees, it’s also just a great time to get out among your fruit trees, which gives you a chance to notice things like this.

A young apricot in close proximity to flowers that have died from Blossom blight disease
A young apricot in close proximity to flowers that have died from Blossom blight disease

There’s no thinning to do here – there’s only one apricot in this site, and it has plenty of room to grow during the season.

But while you’re checking all your fruit, you may notice instances like this where diseased flowers or shoots are touching the fruit.

It’s hard to see but the apricot is attached to the branch on the left hand side of the photo, and touching a diseased part of another branch on the right hand side that is covered with dead flowers infected with a fungal disease Blossom blight.

The disease that causes Blossom blight in flowers also causes Brown rot in fruit later in the season, so left alone, the fruit is very likely to develop Brown rot at the spot where the diseased flowers are touching.

A clean apricot with plenty of space around it to grow into
A clean apricot with plenty of space around it to grow into

So it’s super important to remove the diseased twigs either by pruning them out (it’s always a great idea to keep your secateurs in your pocket while you’re thinning) or just remove them with your fingers.

Doing a spot of summer pruning at the same time as thinning
Doing a spot of summer pruning at the same time as thinning. 
Photo credit: Biomi photo

Depending on your climate most peach, nectarine and plum varieties will have finished flowering by mid-spring and you can see whether or not they’re going to have a good crop and get the thinning well underway.

Though thinning is a crucial job in the lifecycle of your fruit tree, it’s also a quiet and reflective time to spend a dedicated half hour or so with your tree and having a really good look at what’s going on. Enjoy!