What are those brown marks on my apples?

We had a great question from one of our Grow Great Fruit members recently about what causes russet on apples, which describes both the yellow marks (as you can see on the side of this Cox’s Orange Pippin apple), and the rough brown marks around the stem end of the apple.

Russet is one of those curious conditions that occurs naturally – in fact several heritage apple varieties include it in their name, like Brownlees Russet, Egremont Russet and Old Somerset Russet. It’s also commonly seen on pear varieties such as Beurre Bosc.

These days, russet is not considered an attractive trait on apples (have you even seen a russeted apple in the supermarket?), and it’s just one of the reasons many of these beautiful old varieties have gone out of favour (which is one of the reasons we’ve planted a new heritage apple orchard to preserve many of these old varieties).

Russet can also be an injury caused by environmental conditions like frost, sunburn, or hail, or by spraying your apples at the wrong time – even using sulphur (which is an organic fungicide we use occasionally) at the wrong time can cause russeting on some apples (as can a lot of the chemicals used by chemical farmers).

This damage-type russet – think of it like scar tissue – usually happens in the three weeks after petal fall, when the trees are flowering, or when the environmental challenge happens. It is often not a problem in itself, but it can make the apples much more vulnerable to other diseases, like various fungal rots, cracking, or even sunburn.

Heritage varieties that were bred in the UK, such as the divine Cox’s Orange Pippin apples (above) or the much-loved Bramley (below), are really not suited to the harsh and hot conditions in Australia, and so it’s very common to see this type of damage on your apples.

Of course once you realise that, you can set about creating micro-climates that these trees will prefer, and you may find that much of the damage is preventable.

You can find out more about creating micro-climates in your garden in Permaculture in Action.

Netting options for backyard fruit trees

Fruit damage from birds, bats and possums is high on the list of complaints from home fruit growers. This week we look at various netting options,and how they can protect your crop from most of these problems.

The birds left us the stems!

Our new cherry trees are now producing fruit (hooray), and even though we drape netted some of them, it wasn’t completely successful – partly because we were a bit late getting some of the nets on, and partly because the type of birds that were giving us a hard time (parrots) are also particularly clever at getting under drape nets!

So, successful netting is not just about doing it in a timely fashion, it’s also about having the right system for your situation.

Another big advantage of netting your trees is providing some protection against hail, and if you’ve experienced hail before, you’ll know what we’re talking about! Hail storms are a pretty common occurrence on the farm and we lose at least some fruit to hail most seasons.

This is what hail damage looked like on our apricots last year:

Hail damage on apricots

Birds not only damage the fruit, but can help spread brown rot as well. There are lots of different ways to try to scare birds away, such as CDs hanging in the tree, fake predators and the like, but the only real solution is to net your trees – the sooner we all resign ourselves to this necessity, the happier we’ll all be!

This simple net below is made with a frame of star pickets and pipe, and is the easiest and most effective solution we’ve seen (and used).

It’s easy to put up (and take down again if you choose), and easy to peg down around the perimeter to stop persistent smaller birds getting in under the net, which can happen with drape netting (as we saw this year!). This particular set up also has wire netting around the base, which can be useful for stopping larger animals from getting into the enclosure.

Drape netting is easier if you are doing a lot more trees, and is very effective against big birds, and can also deter fruit bats, both of which descend on the tree from above and don’t like to get in under net.

Unless you are really diligent about tying off the net around the trunk, it won’t stop smaller birds like parrots, which are happy to nip under the edges of the net and help themselves. Having said that, it does keep the damage to minimum and is definitely worthwhile.

Learn practical strategies that actually work to protect your fruit from birds and other critters in Protect Fruit from Pesky Pests.

Sunburn strikes again

If you live in a hot climate (like we do) sunburn is an inevitable part of fruit growing, but it can also happen in temperate fruit growing areas during heat waves, which unfortunately are becoming more common due to climate change.

There are three types of sunburn damage you may see:

1. Sunburn necrosis


2. Sunburn browning


3. Photo-oxidative sunburn


This week Ant (who leases our orchard) had his first experience of sunburn, when the Pizzaz plums were not quite ripe enough to pick last week, then the heatwave hit—a blistering day of 44C!

You can see the spots and shrivelling on the skin – that’s a version of sunburn browning. Most of the plums are still perfectly usable for jam, or cooking, or even for eating, but it definitely downgrades them.

Is it preventable? It can be incredibly difficult in cases like this, where there was probably only a very brief window of a day or two when the plums were ripe enough to pick (with the confidence that they would continue to ripen off the tree) before the heat wave hit.

In a home garden, if you were paying careful attention to both your trees and the weather forecast, it may be possible to harvest the fruit (or at least some of it) in time. In Ant’s situation, where he’s managing the competing needs of 5,000 trees it’s much harder.

If you live in an area that experiences heatwaves there’s a number of other things you can do to prevent sunburn damage, including irrigation practices, pruning practices, and careful monitoring—we list 10 different ways to minimise sunburn in “What’s that spot? Common diseases of deciduous fruit trees” (even though sunburn is not actually a disease, but an environmental impact).

The main thing to do when a heat wave is predicted is to make sure your trees are getting enough water, which may mean watering every day. The best time to water is either overnight or in the morning, to reduce evaporation.