How can you tell if your trees are healthy?

If all is going well with your trees this spring, you should be seeing growth like this on your trees:

New spring growth on an apple tree
New spring growth on an apple tree

This time of year we like (and expect) to see a flush of strong, healthy new growth in our trees, particularly on young trees.

Successful fruit growing is all about helping the tree to balance its energy between growing new wood (i.e., new shoots, as you can see in this photo of a young apple tree) and growing fruit. If it grows too much of one, it tends not to grow much of the other.

We need the new wood so the tree continually has new buds being formed to produce next year’s fruit (though the buds can also form on older wood in some trees).

But we don’t want the tree to put too much energy into growing wood at the expense of putting its energy into growing fruit – it’s a balancing act.

Shoot length is one of the best indicators of the overall health of your tree, and spring is the time to monitor it – so visit your trees and have a look.

If you see plenty of young vigorous shoots (anything from a few cm to 1 metre long, depending on the type and age of the tree), you know the tree’s pretty happy.

And if you’ve done a great job with your pruning, you’ll also notice that the new shoots are growing in the right place in the tree to make future fruit picking easy and manageable.

Here’s what healthy spring growth looks like in cherries:

On a young plum tree…

´╗┐Healthy spring growth on two year old plum tree
Healthy spring growth on two year old plum tree

On a mature plum tree…

An Angelina plum tree showing vigorous spring growth
An Angelina plum tree showing vigorous spring growth

and finally, a mature apricot tree that’s growing beautifully (note the beautiful red colour of the fresh new growth, which will gradually fade through orange to green).

Beautiful new growth on a mature apricot tree
Beautiful new growth on a mature apricot tree

To mulch or not to mulch?

Our fruit growing study tour of the USA got us thinking about mulch, as we saw a number of different approaches to it in our travels.

An apple tree mulched with woodchips at the Maine Heritage Orchard
An apple tree mulched with woodchips at the Maine Heritage Orchard

Of course it wasn’t hard to find orchards where the weeds have been completely sprayed out with herbicide, and mulch isn’t needed because there’s no plants left.

Yuk! Don’t do that!

The chemicals are bad for your health, the weeds grow back and need spraying again ($ straight from your pocket to the chemical companies), but worst of all – it’s really bad for the soil and kills the natural fertility system that trees need to get their nutrients (more $ straight from your pocket to the fertiliser company).

So what to do? Should you just let the weeds grow? Won’t they compete with the trees?

For young trees this is somewhat true – it’s definitely helpful to keep the weeds (or you could call them precious understory biodiversity plants) down while the tree’s roots are getting established, and we saw this in action at the Maine Heritage Orchard in Unity, Maine.

This orchard was planted not that many years ago on the site of a disused gravel pit, so major soil building and remediation has been the order of the day.

Hardwood chips have been extensively used, not only to mulch the trees when they were planted, but also to build paths, build soil more generally, and as an ongoing weed suppression tool even as the trees mature.

A tree in Michael Phillips' orchard which was mulched with woodchips when planted and has since been allowed to revert to natural understory
A tree in Michael Phillips’ orchard which was mulched with woodchips when planted and has since been allowed to revert to natural understory

We saw a different approach in Michael Phillips’ orchard in New Hampshire.

He also uses woodchips on young trees, but welcomes a wide diversity of understory plants as the trees grow, using mulch in a more ad hoc way.

There is widespread agreement that if you are going to mulch, hardwood woodchips are preferable.

This is because fruit trees prefer a fungally dominant soil, as we explain in our Soil Biology and the Soil Food Web short course.

Understanding the amazing world of soil microbes that are key to the Natural Fertility System will change the way you think about soil, fertiliser and mulch forever.

So, to mulch, or not to mulch?

After everything we’ve seen, we’re still in favour of mulching while the trees are young, and then transitioning to either a natural or cultivated understory – a “living mulch”!

Fruit tree leaves: bonus or problem?

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?

Autumn apricot leaves on the ground
Autumn apricot leaves on the ground

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.

Blossom blight on apricot flowers
Blossom blight on apricot flowers

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).

Fruit tree leaves starting to break down
Fruit tree leaves starting to break down

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.