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Leaf curl is a nasty fungal disease that affects peach and nectarine trees. It can cause considerable damage to your trees and even cause crop losses in bad cases.

By the time your peach (or nectarine) tree has leaves in spring, you can see if it has the disease. Unfortunately, by then it’s already too late to do anything about it!

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Can all fruit trees get curly leaves?

There are many things that make leaves curl on fruit trees. The causes may be pests or diseases, and it can affect all fruit trees, not just peaches and nectarines.

However, the specific leaf curl pathogen (Taphrina deformans) that causes the symptoms you can see in the photo above only affects peach and nectarine trees.

If your tree gets a bad case, it can even affect the fruit. Really bad infections will even make the fruit fail. Infected fruit can fall off while it’s very small before it gets a chance to grow.

Peach fruit is somewhat protected from the disease by its furry skin. Nectarines are a different matter. Their smooth skin makes the fruit much more vulnerable to infection, as you can see from this photo.

A nectarine infected by curly le
A nectarine infected by Leaf Curl disease

Notice how similar the disease on the fruit looks to the disease on the leaves. You can see the same rough, raised texture and the red colouring.

When should you start monitoring for Peach Tree Leaf Curl?

Peach tree leaf curl actually emerges in spring. However, late winter is the time to start paying attention. This is doubly the case if you saw any signs of this disease last year, or if a wet spring is predicted.

Taking preventive action before the tree wakes up from its winter sleep is your best chance of preventing it from happening again.

When the tree is still dormant in winter, it might seem too early to be thinking about disease prevention, but this is the right time to put out the preventive sprays.

Peach tree flower buds swelling in spring - if you can see pink, it's slightly too late to spray
Peach tree flower buds swelling in spring – if you can see pink, it’s slightly too late to spray

Preventing peach tree leaf curl

The trigger to spray is bud-swell. Different varieties reach bud-swell at different times, which is where the skill comes in.

Depending on where you live and which varieties you have, your trees may already have reached (or be past) bud-swell by mid-winter.

It’s important to be responsive to your trees and the weather conditions, rather than relying on the calendar definition of “spring”.

If your peach and nectarine trees still look completely dormant when you check them, that’s because they are (assuming they’re alive!). From about mid-winter onwards, you need to be monitoring each different variety so you can spray them at the right time.

Choosing the right spray to use

Once you’re sure your tree has reached budswell, it’s time to apply a preventive copper spray.

One of the best options for home use is Bordeaux spray. It’s easy to make at home with these simple instructions. The process involves diluting hydrated lime in water, and copper sulphate in water, then mixing them together.

If the buds on your peach tree are already this swollen, they should have had at least the first copper spray (if not the second)
If the buds on your peach tree are already this swollen, they should have had at least the first copper spray (if not the second)

Bordeaux is messy but a great spray to use at home because it’s quite ‘stickable’ and relatively rain-fast. You can actually see the blue spray residue in the photo above.

Sprays containing copper hydroxide (like Kocide) are also OK to use in home gardens, but avoid other types of copper spray. They are not allowed in certified organic growing (so we don’t recommend them for home use) because they are harsher on the environment.

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