Diagnosing leaf curl in summer

The dreaded Leaf curl disease on a peach tree

We want to talk about Leaf curl. It’s a common fungal disease of peach and nectarine trees (if you have leaves curling in other types of trees it’s caused by something else).

It may seem strange to be talking about it so late in summer, as it’s a disease that shows up in spring, but bear with us!

If you noticed the disease in your trees last spring, the trees should have completely recovered by now, and grown lots of healthy new leaves (that should look something like the photo below).

Hugh with a healthy young peach tree

However if you’re not sure whether your trees had the disease, it may still be possible to find out, as you may still have remnant diseased leaves in your trees.

They’ll look something like this:

Remnant dead leaves from Leaf curl infection in peach tree

In fact, this can be one of the dignostic tools you can use to help identify whether you had this disease in your trees, in the ongoing detective work we need to be doing to become awesome fruit growers!

These dead and shrivelled leaves are a powerhouse of fungal spores sitting in the tree, just waiting until conditions are perfect next spring to release the spores, and start the disease cycle all over again.

A fresh Leaf curl infection on a peach tree in spring

It’s been often and hotly debated whether it’s worth removing infected leaves from the tree as they emerge in spring, and the answer seems to be no, it doesn’t help reduce the spread of infection once it’s started.

However, the jury is still out on whether removing the remnant leaves in summer will help prevent re-infection the following spring. As always, we err on the side of caution when it comes to practical, hands-on jobs you can do to help your trees stay healthy.

So…get rid of them! Many of these leaves will probably have fallen off of their own accord and rotted away under the tree, but if there are any still in your trees, remove and dispose of them.  

Hot compost is the perfect disposal method, as the high temps reached will kill off the fungal spores, but the organic matter in the leaves won’t go to waste.

Remember, prevention is much better than cure, and hygiene is one of the best defenses we have against all pests and diseases.

Another strong defence is using allowable organic sprays in spring, but it only works if you get the timing right. We’ve included a complete spray program to help you decide what and when to spray in the short course Better Fruit with Wise Organic Spraying.

Do wind and fruit go together?

A peach tree blowing in a wild wind

We’ve had some mighty winds over the fruit season. We live in a very windy spot here on Mount Alexander – it can often be completely still in the valley below us, but blowing a gale up here on the farm. 

Wind has a bit of a bad reputation when it comes to fruit trees, and is often blamed for fruit ending up on the ground. But in fact, it’s often only the ripe or over-ripe fruit that ends up on the ground, or fruit that wasn’t very healthy and was destined to fall off anyway.

Apricots on the ground after a big wind

Now it’s quite annoying if the fruit you were about to pick in a couple of days hits the deck, where it often splits, or becomes rapidly full of ants and other critters, so it’s a very good idea to monitor your trees frequently when it’s getting close to the time you expect to pick the fruit.

Lots of varieties need picking multiple times (we pick some varieties four times over a few weeks, just getting the ripest fruit each time), so it’s worth casting your eye over your tree every day or two, and picking just those bits of fruit that are ripe. That way you’ve got a good chance of getting them before wind does.

Wind does have some advantages though, particularly in rainy weather, when it helps your trees dry quickly.

Brown rot in nectarines

The dreaded brown rot fungal disease will only take hold in your trees if they are wet for long enough, at the right temperature, so wind can definitely be the fruit grower’s friend.

If you’re planning to plant fruit trees, or are making changes to your garden, take the wind into account, and try to choose (or create) a microclimate that will allow good air movement around and through your trees.

A Golden Queen peach tree pruned to a nice open vase shape

Also make sure your fruit trees are pruned in an open shape to allow the wind to easily get in the middle and dry them quickly after rain, and make sure any windbreak you plant won’t create a completely still environment for your trees.

Choosing the right time to pick your fruit can be tricky, and is one of the mistakes new growers often make, either picking fruit too green (so it doesn’t taste very good, and won’t ripen off the tree) or too ripe (which can also result in loss of flavour and failure to store well).

However it’s not that hard once you know what to look for, and get to know your trees. Luckily each type of fruit has a bunch of different indicators to guide you, which you can learn about in detail in the short course “Fruit to be Proud Of“.

3 steps to a new tree with bud grafting

Do you know how to graft? Have you tried, but had mixed success? It’s not difficult, but has lots of aspects to it, and is one of those skills (like pruning) that needs practice to cement the theory.

We love it when people who have been to our workshops get back to us to let us know how they went, like this note from Judy, who came to a recent budding workshop.

Just writing to say how thrilled I am to be gazing in wonder and, I must say, anticipation at my very own young nectarines!! These be the first fruits of your terrific budding workshop!”

Judy’s budded nectarine!

If you haven’t heard of it before, budding is the type of grafting we do in summer, and it’s pretty easy. The technique is as simple as taking a single bud from the desired variety, and inserting it under the bark in the graft recipient tree, or rootstock.

It’s interesting that Judy sent us a photo of her nectarine tree, because though budding can be used for all fruit trees, it is the only type of grafting we routinely use for peaches and nectarines, as they tend to be very ‘gummy’ and the more traditional winter grafting techniques don’t usually work, as the big cuts that are required stimulate the trees to respond with a lot of sap, which prevents the graft from ‘taking’.

Grafting is literally thousands of years old. It was known to be used by the Chinese before 2000 BC.  It is one of the basic life skills that underpins our food security because it’s what turns a rootstock or seedling (which may not have good fruit on it) into a known “variety” that will bear reliable, high quality fruit.

Unfortunately it’s almost a lost art, and hardly anyone knows how to do it any more.

We’re on a mission to teach as many people as possible these skills, because if you know how to graft, and you know how to grow your own fruit trees from seed or cutting (which we also cover in our workshops) then you have the skills at your fingertips to create an endless supply of fruit trees for free for yourself, your family and friends, or even as the basis of a small business. 

So, here are the 3 basic steps involved for budding:

  1. Collect a piece of scion wood (grafting wood) from the new variety you want to graft onto your existing tree or rootstock;
  2. Cut a single bud from the piece of scion wood and insert it into a “T” shaped cut in a shoot on the tree you’re grafting onto. Insert the bud into the shoot
  3. Tape it up to seal it while the graft heals.
Our WWOOFer Norma taping up one of her bud grafts

If you’re intending to transform an entire tree to a new variety, then you need to do some preparation work in early spring. Remove most of the limbs from the tree and the tree will respond by growing a forest of new shoots to replace the limbs that have been removed. When it comes to budding time, select the shoots that are in the right place to create replacement limbs and bud them, removing all the other shoots.

Budding success!

We love passing these skills on to a whole new generation of food growers and have developed a short online course that includes theory and videos — you can access it here.

Once you understand the theory, then comes the practice! It’s a good idea to do some budding every year, to maintain and improve your skills. Judy was kind enough to attribute her success to our workshop, but in fact it’s actually her commitment to putting it into action that produced her success:

My good fortune is a result of your good teaching..clear, thorough, hands on..with plenty of practicing..can’t B faulted!! I’m about to do a lot more budding..being February!..Thanks heaps for a terrific course.”

Thanks Judy!