Leaf curl is a nasty fungal disease that affects peaches trees (and nectarines). It can cause considerable damage to your trees, and even cause crop losses in bad cases.
There are other things (both pests and diseases) that can make leaves curl in peaches and nectarines, and also in other types of fruit trees. We cover them in length in this blog. The particular leaf curl pathogen (Taphrina deformans) only affects peach (and nectarine) trees.
If you get 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.
Notice how similar the disease looks on the fruit to the disease on the leaves. You can see the same rough, raised texture and the red colouring.
Why are we showing you what Peach Tree Leaf Curl looks like in Winter?
Peach tree leaf curl actually emerges in spring. However, late winter is the time to be alert. Now is the time to start paying attention if you saw any signs of this disease last year. The same applies if a wet spring is predicted.
That’s your best chance of preventing it happening again next season.
It might seem too early to be thinking about spring. Unfortunately, if you wait until you see the disease, it’s way too late to put out the preventive sprays.
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.
However, if your peach and nectarine trees still look completely dormant, that’s because they are. From about mid-winter onwards, you need to be monitoring each different variety so you can spray them at the right time.
Once you’re sure your tree has reached bud-swell, it’s time to apply a preventive copper spray.
The best options for home use are Bordeaux (which is made by diluting hydrated lime in water, and copper sulphate in water, then mixing them together). This is explained in more detail (with a video) in the Better Fruit With Wise Organic Spraying short course.
Sprays containing copper hydroxide are also OK to use, but avoid other types of copper spray. They can be harsher on the environment, and are not allowed in certified organic growing.