What does healthy blossom look like?

At this time of year the fruit trees look absolutely gorgeous, with many of the apricots, peaches, nectarines, and plums in flower. The early pears and some very early apple varieties have also started to show what we call ‘green tip’, which is the equivalent of budswell in stone fruit.

Because of the huge number of different types and varieties of fruit we grow, some trees are at full bloom, some haven’t started flowering at all, and others have now got tiny fruit – which is one of the most exciting (and slightly scary) times of the year!

The early apricot varieties (our early ones are called Earlicot, Poppicot and Katy) have almost finished flowering and look like this. 

Healthy apricot flowers with petals falling
Healthy apricot flowers with petals falling


This stage of flowering is called shuck-fall, when the petals have fallen off, then the last bit of the flower (the shuck) dries up and falls off, revealing….

A baby apricot emerging from the shuck
A baby apricot emerging from the shuck

…a baby piece of fruit! It’s the same process for all deciduous fruit, and it’s a very exciting transition from blossom to the beginning of the fruit season.

It’s also a good time to start diagnosing some of the common diseases like Blossom blight (common in apricots, but also seen in peaches and nectarines). Healthy flowers look like this when the petals are falling off:

Normal shuck fall
Normal shuck fall

Diseased flowers however will shrivel up, and the petals go brown, like the photo below (despite the best intentions to get all the sprays on at the right time, it’s often the case that there’s still a bit of disease in the orchard when there’s been rain around).

Blossom blight not shuck fall
Blossom blight not shuck fall

It can be hard to tell the difference, but you’ll soon know for sure, when you see if you get any fruit!

The photo below shows another disease symptom you might see, where the flowers have completely died back, and the twig has died back as well. The tree will usually prevent the disease from travelling back any further by producing a blob of gum to isolate the diseased patch (this is one of the causes for the condition called ‘gummosis’).

A bad case of Blossom blight - rotten flowers, and a dead lateral
A bad case of Blossom blight – rotten flowers, and a dead lateral

It’s a good idea to prune these diseased patches out of your fruit trees when you see them (when you’re doing your fruit thinning is a good time), as long as you can do so without sacrificing too much healthy wood or flowers.

Apricots are one of the hardest stone fruits to grow successfully, not just because of diseases like Blossom blight and the many other fungal diseases they are prone to, but also because they flower early and so are very susceptible to early frosts.

But they’re also one of the most rewarding crops for home growers because they’re so versatile and they’re so delicious! With that in mind, we created the Ample Apricots short course to show you how to encourage and nurture your apricot tree to actually bear fruit!

Spring spraying

In organic growing we don’t use chemicals that damage the produce, people or the environment, but that doesn’t mean we don’t spray!

Pink Lady apples with Black spot
Pink Lady apples with Black spot

All deciduous fruit trees are prone to fungal diseases, some more than others, and if they’re not properly prevented or controlled in spring, they can be devastating.

We don’t have room here to go into a lot of detail about individual diseases, so we’ll focus instead on the basic principles of fungal disease prevention.

Each fungal disease has trigger points that stimulate an outbreak of disease – a unique combination of temperature, the number of hours the tree has been wet, and the amount of spores present, amongst other things (we go into more detail about individual diseases in the Keep Your Fruit Trees Free from Disease short course).

Regardless of the disease we’re trying to prevent, the aim is to keep your trees protected at all times while they’re flowering with what we call a “cover spray”

This means we’re aiming to have the trees covered with something that will prevent the fungal spores from causing a disease outbreak.

The regime differs a bit depending on what disease is posing a risk, but the same principles apply. Put an organic fungicide spray on, and then if you’ve had a lot of rain (more than about 25mm, or consistent rain for days on end) assume it’s been washed off and replace it.

Mixing Bordeaux spray
Mixing Bordeaux spray

An effective spray available to organic growers is copper, normally mixed with builders lime (when it’s called a ‘Bordeaux’ mix).

However as always, it’s important to consider the pros and cons. Copper is such an effective fungicide that it can have quite a detrimental effect on the soil because it kills the soil fungi, which are vital to the health of the soil and your trees. So, our compromise is that we only ever use copper once or twice a year.

Peach buds covered with copper spray
Peach buds covered with copper spray

In an ideal world, the tree’s natural defense system (including naturally occurring microbes on the leaves) would prevent a disease outbreak, but for many growers, their trees still need some protection.

Another spray we can use in organic orchards and gardens is sulphur, which is much ‘softer’ and less damaging to the soil, but also less effective at preventing outbreaks of disease. It’s likely to get washed off by rain more easily though, so it may need replacing more often.

Whey is another spray that is often recommended for organic fruit trees, but we’ve not used it ourselves and it’s hard to get any good data about its effectiveness. If you plan to use it please do some ‘citizen science’ and keep good records (including photos) of what you use, when you use it, and your results – and then send them in to us, we’d love to see them and share any new-found knowledge.

On a side note, one of the orchards in the Australian Network of Organic Orchards reported back on a trial he did with potassium silicate and potassium bicarbonate to prevent Black spot fungal disease in apples – and it was almost a total failure! So be warned, if you’re trialing an unproven product set up a small controlled experiment rather than risking your whole crop.

How to Prevent Leaf Curl

Leaf curl is a nasty fungal disease that affects peaches and nectarines, but it’s often confused for other things (well, other things are sometimes mis-labelled as Leaf curl).

Here’s what it looks like:

A peach tree with the classic red leaves of Leaf curl disease
A peach tree with the classic red leaves of Leaf curl disease

There are other things (both pests and diseases) that can make leaves curl in other types of fruit trees, but this particular pathogen only affects your peach and nectarine trees.

If you get a bad case, it can even affect the fruit, and really bad cases will make the fruit fail and fall off while it’s very small, before it gets a chance to grow. Notice how similar it looks to the disease on the leaves, with a rough, raised texture and the red colouring.

A nectarine infected by curly le
A nectarine infected by curly leaf

Why are we showing you what Leaf curl looks like in the middle of winter? Because if you saw any signs of this disease last year, now is the time to be treating your trees to prevent it happening again this year.

It might seem too early to be thinking about spring, but if you wait until you see the disease, it’s way too late to put out the preventive sprays.

A Goldmine nectarine bud swelling
A Goldmine nectarine bud swelling

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, but if your peach and nectarine trees still look completely dormant, that’s because they are. From now on 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 – Bordeaux (which is made by diluting hydrated lime in water, and copper sulphate in water, then mixing them together), or a spray containing copper hydroxide are the best options for home use. The Better Fruit With Wise Organic Spraying short course includes a video demo of how to mix Bordeaux spray if you need more detail.