Should you spray organic fungicide in autumn?

A peach bud in spring with copper spray
A peach bud in spring with copper spray

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.

An apricot with brown rot
An apricot with brown rot

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?

The answer is … sometimes!

In our short course Keep Your Fruit Trees Free From Disease we detail those diseases that can benefit from an autumn spray of an organic fungicide, under certain conditions, like brown rot.

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.

Remove this diseased wood when pruning for good disease control
Remove this diseased wood when pruning, for good disease control

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!

What to do with prunings?

We’ve been busily pruning apricot trees this week, making the most of this beautiful autumn weather and enjoying the glorious colours.

If your apricot tree is like ours, with a spot of gummosis, then it’s very important to pick the diseased prunings up and dispose of them properly to help prevent disease next year.

The best way is to return them to the soil somehow. Large animals (sheep, goats, horses) just love to eat prunings (especially if they still have green leaves on them), and will often break them down enough to put the remains straight into a compost pile.

Now that we have Tessa’s in-house micro-dairy here on the farm as part of the Harcourt Organic Farming Co-op, the prunings go straight to a bunch of cows who think fruit tree prunings are a high treat!

Another great technique is to chip the prunings. You can either leave them in a pile to age and then put them back on the trees, or put them into a compost pile. Learning how to make your own compost is one of the “must-have” techniques for all gardeners that are serious about growing their own food. It’s really hard to find good quality compost to buy (not to mention quite expensive, as it’s something you need to apply regularly), plus it’s one of the best ways to capture the nutrients from your garden ‘waste’ and return them to the soil. If compost-making is still a mystery (or keeps going wrong), our Compost That Works online short course will get you on the right path.

Larger prunings also make good kindling or firewood, or can be turned into biochar using one of the techniques we’ve described in other blogs, so there’s really no need to waste anything!

Is rain good for fruit?

A lemon covered in raindrops
A lemon covered in raindrops

As a fruit grower, lying in bed listening to rain on the roof can bring up a wide range of emotions, both good and bad. In our typical dry summers most people welcome rain when it comes, so it never seems appropriate for us to express concern about the damage it can do to fruit. However, it hasn’t rained for a while, so this week we reflect on the question – “Is rain good for fruit?”

Like everything in farming, the answer is complicated, and depends on lots of different variables, so let’s break it down a bit.

1. Trees like rain better than irrigation waterup to a point! As a gardener, you’ve probably noticed how “perky” your garden looks just after rain. One of the reasons (apart from the leaves being cleaner) is because the rain carries dissolved nitrogen which is easily absorbed by the plants, giving them a nutritional boost. Too much rain, however, and the soil can become waterlogged, creating anaerobic conditions, which actually stops the plants’ roots being able to take up nitrogen! The other advantages of trees receiving their water from rainfall (rather than irrigation) are that the entire root system gets water (rather than just at the point of water delivery), and if you’ve been keeping your garden on rations due to dry conditions, they just love the opportunity to get their fill of water for a change!

A fungal disease outbreak on an apricot
A fungal disease outbreak on an apricot

2. Rain can trigger fungal disease. One of the biggest pest and disease risks in an organic farm (or garden) is fungal disease, and nearly all fungal diseases are triggered by wet conditions (at the right temperature). In general terms, the more rain, the more fungal disease. This risk is highest at the beginning of the season (i.e., at flowering time in spring), and then gradually decreases as the season progresses. During autumn, if the summer has been generally dry and there is not much fungal disease around, the risk of a new fungal outbreak is relatively low.

Cherries that have cracked in the rain
Cherries that have cracked in the rain

3. Rain can cause physical damage to fruit. This is very specific to the type (and even variety) of fruit. For example cherries are particularly vulnerable to splitting from the rain, and some varieties of apricots also split easily. Hardier fruit like apples and pears, however, rarely experience physical damage from rain.

An apricot with a severe crack caused by rain
An apricot with a severe crack caused by rain

4. “Hard” rain can damage all fruit. Storms that bring rain often also bring hail, and that can be completely devastating to all fruit. Hailstorms are very random and localised, so it”s pretty much the luck of the draw with this one, though if you live in a hail-prone area, netting can definitely be your saviour. All fruit are vulnerable to hail damage, including apples, pears, plums and quinces.

5. Rain is good for the landscape. When you’re trying to grow food in an arid landscape (as we are), the general impact of rain (as long as there’s not too much, or too quickly) is generally FABULOUS! It fills water storages, keeps the bush alive, helps to sustain our farming communities, and helps backyard fruit growers maintain their own food security. We love it….except…. when there’s too much! If rain becomes flooding and the soil becomes saturated for too long, it can lead to ALL sorts of problems! Anaerobic soil conditions, trees dying, waterborne soil disease, nutrient leaching, dams breaking their banks, and the list goes on. We’ve seen it before when the drought broke in 2010/11.

A rainy morning and green grass
A rainy morning and green grass

6. Rain is good for mental health. It’s a generalisation, of course, but very often rain can be a huge relief to farmers and others in the community, especially if it is relieving the pressures of trying to farm in a dry landscape, though as you can probably see from our list, it totally depends on the amount of rain, and the context!

Poppy lapping up a puddle
Poppy lapping up a puddle

Regardless of the timing of rain within the fruit season, it’s important to make sure your soil can act as a big “water storage tank” when it rains. As well as building really healthy soil (which is good for both water storage and drainage in your soil), techniques like swales and keyline (covered in this short course) can make a huge difference to how well your soil will store rainfall.