Here’s a question we were asked recently: as the leaves fall off your fruit trees, is it OK to let the leaves rot on the ground, or are you potentially creating a disease problem?
Issues like this are often decided by comparing the costs (in time, money or effort) of taking action, against the benefit.
Plus, you’ve got to consider what you’d do with the leaves if you collected them, and factor this into the equation. If they can go into an active compost system, or be fed to animals, and therefore returned to the soil, this is a very different outcome to filling up your greenwaste bin, or – horror of horrors – putting them in landfill!
In this case we’re weighing up the benefit of the lovely organic matter and nutrient provided by the leaves returning to the soil, versus the potential risk of fungal disease from any spores that are on the leaves, which may create disease in the tree next season, like Blossom blight, for example.
So, how to decide?
The rule of thumb is that it’s beneficial to let the leaves rot under the trees as long as they break down quickly (within a couple of months, and certainly before next spring).
If you have reasonably healthy soil with an active soil food web and plenty of worms, there should be no problem and the leaves will break down quickly. The soil food web and the key role it plays in the health of your garden is explained in detail in this short course.
If you find they’re not breaking down fast enough you can help them along by mowing them with the mower or slasher, and either sprinkle a bit of compost on top, or spray them with compost tea or worm juice to help them along.
This is a great example — an apricot tree with both Katy and Trevatt apricot branches. Katy is an early apricot that is a bright orange colour, firm texture, slightly oblong shape and terrific flavour that combines sweetness and tartness. It’s also a reliable cropper.
Trevatt is a more common apricot that you may have heard of — it’s a heritage variety (dating from the 1900s, developed in Mildura), and is completely different to Katy. It ripens about a month later, it has pale lemony-orange skin, and is a super-sweet apricot with very little tartness. It also has a much different texture, ripens from the inside, and is much softer — it can even go a little mushy if allowed to get overripe.
So, will a multigraft suit you? They’re much less well-known, and many gardeners are a little hesitant to try them out.
It’s almost a no-brainer that a multigraft is a better use of the space in your garden, unless you have space for a LOT of fruit trees and would prefer to have whole trees of each variety. Considering that a mature tree can easily yield up to 40 or 50 kg of fruit (or more) in a good season, it usually makes sense to spread the harvest over a longer period, rather than have a massive glut to deal with all at once.
There’s a couple of other great reasons that multi-grafts can work well:
pollination: in this example both varieties are self-fertile, but even self-fertile trees can benefit from having pollen from another variety close by, and this can help to increase yields;
spreads the risk: apart from the issue of gluts already discussed, some seasons just don’t favour some varieties. For example, if you happen to get a frost just at the time when the Katy are at full bloom, the Trevatt may be later coming into bloom and might therefore have less frost damage. Another scenario we’ve seen many times is rain affecting one variety that is almost ripe, causing it to split, while another variety that is still a month away from picking can escape relatively unscathed — so the more varieties you have, the better your chance of at least getting some fruit every year!
disease resistance: different varieties may be more vulnerable to particular diseases, like blossom blight or brown rot, either because of the difference in their ripening times, or just the natural resistance of that variety.
A fruit salad tree is like a multi-graft on steroids!
This extends the concept to include different types of fruit on the same tree, rather than just different varieties of the same type of fruit. In the example we’ve included here, you get both!
This tree has three varieties:
Katy apricot (described above) – ripens late Nov
Trevatt apricot (described above) – ripens late Dec
Angelina plum – an early season European plum, very sweet, with beautiful dark purple skin with the traditional dusty-looking ‘bloom’ on the skin. These plums are incredibly delicious and versatile – you can eat them fresh, dry them, bottle them, jam them or make them into wine, just to name a few. They’re also a favourite for the classic European plum dumplings, or plum cake. They’re a really good plum to include in the garden.
Angelinas ripen in January – so with just one tree you’ve already extended your harvest over three months, as well as given yourself a pretty good variety of fruit to enjoy and preserve.
We love creating multi-grafts in our on-farm nursery (called Carr’s Organic Fruit Tree Nursery), and have quite a lot of different combos on sale this year — you can see our selection of multi-grafts here.
At the moment we’ve limited it to apricots and plums (though we have plans to extend it to apples, pears and peaches), but there’s heaps more you can do in your own garden, by learning how to graft new varieties onto existing trees.
It’s such a brilliant and easy way to extend your fruit season and increase the variety of fruit in your diet that Grow Your Own Fruit Trees for Free is one of our favourite short courses, and probably the best one to start with if you’re new to grafting. We also have specialist courses on individual grafting techniques when you’re ready for them.
There can be a couple of drawbacks with multi-grafts though.
One of them is that the trees can come out of the nursery a slightly unusual shape (as you can see from the photo above), and so require a bit of careful management to establish as a useful ‘vase’ shaped tree.
The other main issue is that one variety may dominate the tree, and again, may need some attention when pruning to help keep the tree balanced. A handy tip is to plant the tree with the weakest branch pointing north, where it will be favoured by more sunlight.
But really, the management issues are usually handled easily during the regular “getting to know you” phase of your relationship with the tree, and once established, they usually settle down and crop beautifully.
A lot of people don’t think “organic” and “spray” go together, but actually there’s a couple of relatively ‘safe’ sprays that certified organic growers can use, under strict organic standards.
The only sprays we use are organic fungicides — a little bit of copper, and elemental sulphur — because in a wet season they can make a huge difference in preventing some particularly nasty fungal diseases if you use them in spring.
Some people also recommend spraying fungicides on fruit trees after the crop has been picked in autumn, to clean up any residual disease, but this is a bit more controversial.
So, when is the right time to spray? Do your fruit trees really need an autumn fungicide?
So we certainly don’t rule it out, and it can be a useful part of an overall strategy for cleaning up some diseases. However, in most reasonably healthy trees, you don’t need to routinely use a fungicide.
And that’s a good thing, because even organically allowable sprays can have an impact on the environment, particularly the soil, and you should only ever use the minimum amount necessary, and strive instead for a really rich biodiverse garden where natural immunity will be at its highest. (And you should never use chemical fungicides.)
If you’ve had a dry season – as we have in central Victoria this year – there’s been very little fungal disease.
Under these conditions our strategy includes pruning any diseased wood out of the tree, and totally removing it from the tree and the orchard floor, but we won’t be needing to put on a spray at all. Excellent!