The Anzac peaches (one of the first to flower at our place) have set a good crop as usual. If you have this – or any other early season varieties – it’s time to start thinning.

Now that the flowering has finished on these trees, and the leaves are starting to grow, it’s a good time to assess the crop. Look particularly for the impact from a couple of common diseases. They can play havoc with our fruit trees, often without our realising it. 

As well as peaches, you’ll also be thinning apricots soon (if you haven’t already started). While you’re doing so, it’s a good time to look out for signs of blossom blight in your tree.

Castlebrite apricot tree showing the signs of a blossom blight infection, a disease that can also affect peach trees
Castlebrite apricot tree showing the signs of a blossom blight infection

Even though this disease does most damage when the tree is flowering, it can also affect the fruit that has set. This is because the disease that causes blossom blight also causes brown rot.

It’s not unusual to see remnants of it alongside healthy apricots, if you’ve had a mild case.

Flowers infected with blossom blight´╗┐, a disease that affects mainly apricots but also peaches
Flowers infected with blossom blight

What should I do next to look after my peaches?

If you notice any of these diseased flowers on your apricot or peach tree (and you also have healthy fruit) then knock or prune any diseased flowers and shoots off. This is for two reasons:

The first is that they can contribute to disease outbreaks next year. However the more urgent reason is that the pathogen that causes blossom blight also causes brown rot this season. Young, developing fruit is very vulnerable, as you can see in the following photo:

Photo showing Brown rot infection of a young apricot (blue arrow) that started from a flower that died due to Blossom blight infection (red arrow)
Photo showing brown rot infection of a young apricot (blue arrow) that started from a flower that died due to blossom blight infection (red arrow)

The other disease to check for is leaf curl, which is usually fairly obvious, the red leaves are a dead giveaway.

´╗┐Leaf curl on a peach tree
Leaf curl on a peach tree

Luckily, only peaches and nectarines are affected by this disease. However if you’ve had a really bad case, it can also affect the fruit. This is another thing to look out for while you’re thinning, because you may as well pull the infected fruit off.

Affected fruit looks like this:

Leaf curl infection on a Goldmine nectarine
Leaf curl infection on a Goldmine nectarine

But I sprayed already…

It’s not uncommon to end up with one of these infections despite having sprayed, which is super annoying.

There’s a few potential reasons for this. The first is that you may not have the right spray equipment for the size of the job you need to do. You can review the various options in this short course. If you’ve gone to the trouble and effort of spraying, it makes sense to be sure it’s going to work!

The second reason is that you may not have got the timing quite right, and the right conditions were in place for the fungal disease to take hold in the tree unimpeded.

And the third most common reason is that you didn’t spray often enough – or that the spring was just too wet, depending on how you look at it!

Of course the long term aim is to get your orchard and trees healthy enough so they don’t need spraying, but while you’re building your biodiverse paradise, a bit of crop protection can go a long way!