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A lot of people don’t think “organic” and “spray fruit trees” go together.
That’s because as soon as people hear the word “spray” they assume there are toxic chemicals involved. And honestly, in the conventional food-growing world, they usually are.
But actually, spraying is just a technique that can be used to apply lots of different things to your fruit trees.
It’s definitely better to aim for a healthy, biodiverse system that keeps itself in balance without any spraying for pests and diseases at all.
However, there are actually a couple of sprays you can use that won’t do damage. These are the ones that certified organic growers use (under strict organic standards, of course).
Usually, when people think of spraying their fruit trees, they’re thinking about preventing or treating pests or diseases.
But spraying can also be a great technique for feeding your trees.
How can spraying feed your fruit trees?
Spraying to give your trees nutrition (called “foliar spraying” or “foliar fertilising”) is a different kettle of fish altogether. In effect, it’s a way to feed your fruit tree through its leaves.
Foliar fertilising can be a quick, effective way of giving your trees a nutrition boost or correcting a deficiency.
The best time to do foliar fertilising is during the fruit season, when the trees are at their most active. By autumn, when the leaves are starting to change colour it becomes much less effective.
It’s important to remember that the main place your trees get their nutrition is from the soil. Foliar sprays can’t replace or make up for poor soil or an inadequate soil health program.
Foliar fertilisation is a great tool in your toolbox, but it’s not something we routinely recommend for most home growers, and it’s not an autumn job.
When’s the best time to spray for pests and diseases?
The main sprays we use on the farm are allowable organic fungicides. In Australia, that means a little bit of copper (of the right formulation), and elemental sulphur.
In a wet spring, they can make a huge difference in preventing some particularly nasty fungal diseases.
You may have seen recommendations to spray fungicides on fruit trees after the crop has been picked in autumn. It’s often recommended as a way to clean up any residual disease, but it’s a bit more controversial.
So, how do you know if your fruit trees really need an autumn fungicide?
Get to know your disease
Truth is, each disease is different. It’s really worth identifying which diseases have been a problem for your trees in your garden, and understanding how they work.
Some diseases like leaf curl aren’t usually controlled with autumn spraying. But others like brown rot can benefit from an autumn spray of an organic fungicide.
And then there are other situations where spraying may help:
- If you’ve had a really bad outbreak of Black spot (Apple scab) on your apple trees, spraying with compost tea or worm castings can help them to break down before the following season;
- If you’ve a bad aphid or scale outbreak, spraying with winter oil (also called horticultural oil) can help to smother the eggs and prevent an outbreak next year
So we certainly don’t rule autumn spraying out.
It can be a useful part of an overall strategy for cleaning up some diseases and controlling some pests.
Spraying less is best
However, in most reasonably healthy trees, you don’t need to routinely use a fungicide at this time of year. And that’s a good thing because even organically allowable sprays can have an impact on the environment. They can particularly impact the soil.
We reckon it’s a good idea to keep spraying organic fungicides to the absolute minimum. And you should never use chemical fungicides, because it’s easy to damage your precious ecosystem.
Instead, strive for a really rich biodiverse garden, where natural immunity will be at its highest.
Rainy conditions lead to more spraying
It’s also important to take your local conditions into account. Fungal diseases love wet conditions, and if you’ve had a wet summer then your trees might have suffered badly from disease. In that case, an autumn fungicide might be a good idea to help reduce the fungal load.
However, if you’ve had a dry summer then it’s likely that there’s been very little fungal disease around.
You can often manage your hygiene just by pruning any diseased wood out of the tree. Then make sure you take it away from the tree altogether and dispose of it elsewhere.
But there’s no need to put on a spray at all.
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