Is your tree water stressed?

How do you know if your trees are moisture stressed? In spring it can be hard to tell, but it’s a crucial time to make sure your trees DON’T dry out, particularly if they’re still flowering.

Gala apple blossom
Gala apple blossom

Why is it a problem?

In spring while the fruit is forming it goes through cell division, and if it doesn’t have enough water, there won’t be enough cells formed in your fruit.

Once that has happened, then it doesn’t matter how much water your trees get later in the season – you can’t correct this problem because the cell division phase is well and truly over, and you’ll be sentenced to a year of small fruit.

We learned this the hard way during the millenial drought. In our district here in central Victoria, traditionally there’s enough winter rainfall that there’s plenty of water in the soil in spring, and fruit trees never get water stressed at this time.

Small Anzac peaches that didn't get enough water early in the season
Small Anzac peaches that didn’t get enough water early in the season

After one particularly dry winter during the drought we had to endure a year of tiny fruit (see the peaches above – urgh!) so we quickly learned that we had to start watering the trees much earlier than usual, and it’s now one of the conditions we keep an eye on as we come out of winter each year.

With much of Australia in drought and a hot summer predicted, it’s worth noting that heat waves are another time when it’s really important to monitor your fruit trees for water stress.

Here’s an extreme example of a really dry tree:

Apple trees that haven't been watered
Apple trees that haven’t been watered

We’ve always had heat waves here in Australia, but their frequency and severity seems to be increasing. There’s not much we can do about that (apart from trying to slow down climate change), but we can make sure our trees are adequately irrigated, particularly during a heat wave, to minimise the stress on the tree.

The easiest way to check whether your trees need water is the ‘boot test’ – kick the soil under the tree with your boot and if you see dust, the tree needs watering!

Going up one step in sophistication is to dig a hole a few cm deep near the trunk of the tree with a shovel; the soil should feel cool and moist. If it looks and feels hot and dry, and is very hard to dig into, it’s too dry. (There are also many more degrees of sophistication with moisture monitoring equipment, but in most cases it’s not necessary).

The most sustainable way to protect your trees from inadequate water is to continually improve your soil quality, which in turn increases the amount of water your soil can hold. Learn how to store water in your soil here, and how to improve the health of your soil without expensive additives here.

A tree with a blocked dripper
A tree with a blocked dripper

And finally, check your irrigation system regularly! A quick 5 minute check every couple of weeks can prevent this situation, where a blocked dripper was discovered because the leaves turned yellow and started to fall!

Capeweed – love it or hate it?

Capeweed - pretty yellow flowers, but is it a desirable plant?
Capeweed – pretty yellow flowers, but is it a desirable plant?

We’re often asked what we think of capeweed, which is often seen growing in great abundance all over the countryside (and our farm) in spring.

If you’ve been following us for a while, you’ll know we’re generally big fans of weeds (we even wrote a short course about it called Learn to Love Your Weeds,) but does the same apply to a huge monoculture of one weed?

A yellow carpet of capeweed in the orchard
A yellow carpet of capeweed in the orchard

Capeweed germinates in autumn and winter, so is most evident in spring, dying off in summer – and that creates a problem right there, because where you have an over-abundance of capeweed, you end up with bare ground in summer – which is a terrible thing for the soil.

It’s basically a weed of cultivation, pastures, lawns and disturbed areas. Stock will eat it but don’t like it (and the woolly seeds can cause impaction), it can taint milk and where it’s the dominant feed, nitrate poisoning of stock is possible.

Sounds terrible doesn’t it?

A bee gathering pollen from capeweed flowers
A bee gathering pollen from capeweed flowers

But the problem is not the capeweed itself. It can actually play a useful role in covering bare soil and keeping it cool, attracting bees, and – when part of a rich biodiversity of plants – filling a niche in the ecosystem.

The problem is the soil – and even more importantly, the practices that have led to soil and diversity imbalances that result in this kind of destructive monoculture.

A carpet of capeweed is a stark visual reminder that whatever we’ve been doing to the soil is all wrong! It’s an indicator of acid soil, compaction and can be an indicator of waterlogging or salinity.

It’s telling us to sit up, take notice and change our practices immediately.

We need to get more organic matter into the soil, rebuild a wide diversity of plants, and particularly focus on including plants that will stay green throughout summer.

The work of eminent Australian soil scientist Dr Christine Jones (www.amazingcarbon.com) tells us that bare soil should be avoided at all costs as it heats up to at least 60C in summer, which causes it to rapidly lose moisture, kill soil microbes, and contribute to climate change!

So, that’s the long answer!

The short answer is that while a mooculture of capeweed (or any plant) has its drawbacks, it’s a fantastic indicator plant, a good bee attractor, and can be a very useful member of a healthy biodiverse garden or pasture.

Diversity, soil, and the amazing Christine Jones – a vollie’s view

Alistair and Tess on the farm
Alistair and Tess on the farm

Hi, I am Alistair Tuffnell and I’ve come up to Harcourt Organic Farming Co-op for a few weeks to get some experience with Tess and Ollie on their dairy farm.

On Tuesday this week I went with Tessa, Ant, Katie and Hugh to the Dr Christine Jones workshop.  

Straight away I was surprised and captivated by the stats and facts that Dr Christine Jones was stating.

Fifty percent of USA males are infertile due to (my understanding of what Christine said) their gut microbiome being deficient because of really poor diet and a lack of diversity of plant species.

Autoimmune disorders such as autism are rising exponentially today and this is highly related to and (my understanding is it is) even caused by a lack of plant species in our diet.

We humans need to get at least 20 plant species in our diet weekly. A person who eats industrialised meat will have the same gut biome as a person who is on antibiotics. And so on…   This led into Christine making the point that we live in a microbial world, ‘microbes can control the world, microbes are smarter than biogenetic scientists’.

We need to coordinate them more in our soils.  Agriculture is about food – ultimately grown in and from the soil – and at this point in time our food has never been less nutritious.

Since colonisation in Australia there has been a staggering mineral depletion in our soils but according to Christine ‘our soils are not mineral deficient but are deficient in microbes’.

Christine defined soil as ‘weathering rock materials (sand, silt, clay) that are in contact with plants’ – so bare ground must not be soil!  

Dr Christine Jones explaining how bare soil contributes to climate change
Dr Christine Jones explaining how bare soil contributes to climate change

There was so much information presented and I am sure I missed much of it with my novice soil and tiny farming experience but some of the things Christine talked about stayed with me. Such as the presence of green plants are the most important factor of soil health. That water vapour from bare ground (we can’t see it) is the main driver of climate change. That plant root inputs build soil 30-50 times faster than compost does – it is the chemical signals of the microbial process that make plants so intelligent.  

I walked away from the workshop thinking diversity, diversity, diversity – in what to eat and in what to grow as cover crops.

To improve our soils I understood Christine recommended to grow about 20 different cover crops according to the Intermediate Disturbance Hypothesis, which I don’t understand but I can look at her website to try. www.amazingcarbon.