Fruit - Peaches and Nectarines

Introduction

Anyone who has tasted a peach or nectarine from a home garden will know that there is no comparison between home-grown peaches and nectarines and what is for sale in the super markets. Add to that the fact that there are many dwarf peaches and nectarine varieties for sale that can be grown in small spaces or pots, and you have a very compelling case for a peach or nectarine tree in every garden.

This is a blog post in the Fruit-series by Max and Max. It covers buying, planting, pruning, grafting and pest control of peach and nectarine trees, and harvesting and storing of their fruit. Thank you, Max, for your expert-feedback and valuable contributions to this blog post! 

General cultural notes for peach and nectarine

• They are the same plant species: a nectarine is simply a peach cultivar with a smooth skin. Nectarines are not a mix of peach and plum.
• Lifespan: peach and nectarine trees live a much faster life than apple and pear trees. They grow fast, produce a lot of leaves and fruit if the conditions are right, but a thirty-year old tree is near the end of its life.
• Soil: peaches and nectarines prefer lighter soils than apples and pears. They do not like clay soils with bad drainage.
• Water: peach and nectarine trees do not like dry conditions. The best-tasting fruit will be produced when these trees are regularly watered throughout the season. Drip-irrigation is ideal because it is best to avoid wet foliage, especially in humid conditions.
• Frost: peaches and nectarine trees are best put in positions that do not get frost. They flower early and their flowers do not tolerate frost well.

• Grass and weeds: in many gardens grasses go right up to the stems of fruit trees. Fruit trees root shallowly. For young trees especially, remove all grass between the stem and the drip line (that is the circle where the foliage ends).
• Mulch: woody mulch is preferable over other types of mulch as it encourages fungi and other micro-organisms that are beneficial to fruit trees. Apply a generous quantity!
• Nitrogen: Peaches and nectarines need more nitrogen than most other fruit trees. If leaves are yellow or small, the tree needs more. A mulch of mature poultry manure in autumn, soon after the harvest, will provide this. Blood and bone will also do the trick. Make sure to go up to or beyond the tree’s drip line.
• pH: test the pH of soil under your tree a few months after applying blood and bone or mature manure. If pH is below 6.5 apply lime or dolomite in winter. For peach and nectarine trees dolomite is preferable over normal lime, as it contains potash.
• Potash: peach and nectarine trees love potash. If the pH is right, and you are therefore not going to apply dolomite, instead apply sulphate of potash in spring. Potash improves water retention, encourages strong flower and fruit development and improves disease resistance.

Buying peach or nectarine tree

By far the best time of year to get a peach or nectarine tree is when dormant bare-rooted trees are for sale at nurseries and hardware stores in mid-winter.

Bare-rooted trees that are left in nurseries at the end of the dormancy period are potted up and are then for sale for the rest of the season. Buying trees in pots will be fine in many cases, but you don’t know how long the tree has been in the pot, it will cost more, and the tree may not respond well to being transplanted while not dormant.

Ideally you start thinking about and planning for your new peach or nectarine tree in mid-autumn. When trees become available in mid-winter, you will find them in hardware stores, but the choice of varieties will be limited. In order to get some of the tried-and-proven varieties that do well in Tasmanian conditions it might be better to order a tree from a reputable Tasmanian nursery when they open for fruit tree orders in late autumn. The trees will then be ready for pickup in July – August.

All peach and nectarine trees are grafted these days, so you get the benefit of good fruit and a rigorous root system. There are now so many varieties, and new varieties are constantly released, that it is not helpful to name popular varieties.

Colour and taste are another factor to consider: For both peaches and nectarines there is the choice between yellow, white and even red-fleshed. It’s not just a case of what colour you like. They taste differently. Ideally you may be allowed to taste fruit of a tree in someone else’s garden and then decide ‘that’s the one I want’.

Some varieties are freestone, which means that, when ripe, the pip comes away easily from the flesh. With clingstone varieties it is more difficult to separate pip from flesh.

There are early or late ripening varieties. In Tasmania, with its unpredictable cooler climate early to mid-season varieties might be most rewarding.

Most but not all peach and nectarine varieties are self-fertile. This means that you only need one tree to get a good crop. Check before you buy, as you will need two trees to get the best results with varieties that are not self-fertile!

Consider a dwarf tree (a tree that will stay small because it is grafted onto dwarfing root stock), as it will take less space, and will be easier to maintain. The taste of fruit of some dwarf varieties is not as wonderful as that of full-size nectarine and peach varieties.

Different peach and nectarine varieties need different amounts of chilling time during winter (that is hours of temperatures below 10 degrees) to produce a good number of buds. This is why a variety that does well in Southern Queensland or NSW will not necessarily be available in Tasmania, or do well here.

When picking up the tree from the nursery in mid-winter, inspect it right there at the nursery before taking it home, including the roots. Ask for a different tree if it does not look healthy. Inspect the graft. There should be no split bark or gum oozing from it.

The list below may help you select the right Peach or Nectarine variety for your garden. The varieties mentioned here all produce good quality fruit.

Peach (in order of ripening – earliest first)

• ANZAC - early, white, freestone
• Red Noonan – white, freestone
• Coronet – yellow, medium to large, freestone
• Redhaven - early to mid-season, yellow, freestone
• Loring - medium to large, yellow, freestone
• Suncrest – large, yellow, freestone
• Fragar - white, clingstone
• Golden Queen – yellow, late ripening, clingstone, amazing when preserved

Nectarine (in order of ripening – earliest first)

• Independence – yellow, freestone, rich flavour
• Early Rivers – white, freestone
• Flavortop – large, yellow, freestone
• Goldmine - old late variety, white, clingstone

Planting a peach or nectarine tree

You can make a really good start with the prevention of pests by planting your tree in a well-drained location with full sun (6-8 hours during the growing season). Make sure there is always ample opportunity for air flow between trees, even when they reach full size.

A damaged trunk is an easy access point for fungi. Don’t put your peach or nectarine in a situation where you may mow right up to the trunk and damage it. It is best to remove all grass and weeds around a young fruit tree, cover the ground with woody mulch, and keep it weed-free.

Find a spot where the tree will be able to reach a good size without shading other plants.

Avoid planting a peach or nectarine in a very windy spot as branches may break and soil may dry out.

Consider a space along a north-facing fence or wall and espalier the tree!

It is best to prepare the spot where the tree will be a number of months before planting time.

Explore the spot by digging a large hole. Assess the quality of the soil. Fill the hole with a bucket of water. If the water is still there a few hours later, find another spot, or create a mound that will drain well and plant the tree in the middle of the mound.

Are you finding that roots of other trees have claimed this spot? If so, your new fruit tree may have too much competition from nearby trees. Fill the hole with a mixture of soil and mature compost and/or mature manure. Let this settle for a few months, until mid-winter, when you will plant your tree.

When arriving home with the tree in mid-winter, plant it as soon as possible. If you don’t have time right then, heel it in a temporary position (for up to a few weeks) by burying the roots in some loose soil and keeping the soil moist.

Plant your young tree the following way:

1. Remove all saw dust or other moisture-retaining materials around the roots.
2. Don’t prune the roots unless they are very long.
3. Soak the tree overnight in a bucket of water + seaweed solution.
4. The next day, plant it deep enough, so all the roots are covered by at least 10 centimetres of soil. Make sure that the spot where your variety was grafted onto root stock, is well above ground level.
5. Put two stakes in the ground at opposite sides of the tree, and tie the tree to the stakes with flexible tree ties.
6. Immediately surround the young tree with mesh if wildlife is a problem in your garden.

Pruning at time of planting is not in the list above. Peaches and nectarine trees are very prone to fungi attacks (see section on pest control below). While your new peach or nectarine tree is dormant it can’t heal pruning cuts quickly and this makes it a target for fungi, so it is best notto prune at the time of planting in mid-winter. Prune it around the end of October once it has woken up and you see some activity. At that time prune your new young tree so it begins to take on the shape of a vase. Cut away most of the central stem. Leave untouched four main side-branches that are most promisingly arranged around the middle. Remove other branches that are the not well-positioned or weak or broken.

Most fruit tree growers do not prune their young trees at all before they go to the customer, because they know that customers like big well-developed young trees. Many buyers also don't prune it. If the young tree is not pruned when it has come out of dormancy, its often-minimal root system will struggle to feed all the branches, and the shape of the tree will not be ideal for a productive life.

In its first year in the ground the young tree will focus on forming a good root system. Don’t be disappointed if not a lot happens above ground, and don’t expect any fruit.

Water a young tree well during its first year as its root system may not yet be developed enough to cope with long periods without rain. In that first year wait with compost, manure and foliar feeding until the tree is recovering well in mid-summer.

If your tree came in a pot, do not just plant it straight from the pot into the ground, because roots may have started to curl around in the pot, and will continue to do so in the ground (restricting the tree’s growth), if you don’t correct this problem. Remove most of the soil, straighten the roots, and then spread them out in a hole that is big enough to allow roots to go outwards. Don’t cut the roots unless they are very long. Give the tree a hard prune, so it has less foliage to take care off, while it recovers. Planting a peach or nectarine outside the dormancy season is not ideal, so keep an eye on it, and make sure its soil remains moist, but not sodden, at all times.

Pruning a peach or nectarine tree

The number one pest problem with peach and nectarines is not insects but fungi. Pruning to keep peach and nectarine trees open to air and sun is the number one strategy to minimise or ideally avoid fungi problems.

Prune in autumn once the foliage at the end of branches has stopped growing and before the tree goes dormant. At that point in time sap is no longer rising in the tree (hence no new growth), but the tree still has enough energy to quickly repair the wounds that the pruning has made. Late April might be a good time, but it can be earlier or later, depending on the weather, and depending on the variety of the tree.

If you prune too early the tree will produce new growth after pruning, and that new growth may not be hardened enough to cope with frosty conditions in winter.

If you prune in winter, cuts won’t heal quickly because the tree is dormant. Slowly healing cuts that are exposed to cool and wet conditions are an easy target for fungi. Avoid pruning in winter if at all possible.

Pruning provides ventilation and therefore is a preventative measure against diseases. It also makes pest control, netting, and picking of fruit far less arduous.

Ideally a young nectarine or peach tree is ‘trained’ to take on a particular shape and height in its first four years in the ground. If this is done well, and its shape is right, the tree then needs less pruning in subsequent years. When it is pruned less, the tree is not encouraged to ‘grow wood’. Instead, it will spend more energy ‘growing fruit’. Ideally in old age, a well-shaped nectarine or peach tree does not need a lot of pruning and continues to produce well.

General pruning rules:

1. Use sharp clean secateurs: see 'getting the best out of your secateurs' in blog post Pruning Berries
2. For a young tree focus on getting the shape of the tree right, not on getting fruit.
3. Make clean wounds that are as small as possible.
4. Do not treat wounds with wound sealants. It might do more harm than good.
5. To avoid taking diseases from one tree to the next, before starting on the next tree, wipe secateurs with methylated spirits or a mix of water and household bleach.

The best method of pruning peach and nectarine trees is quite different from the way apple and pear trees are pruned.

Peach and nectarine trees only form flowers and bear fruit on wood that was created last year. Thereafter that wood will never be fruit-bearing again. If left untouched, a branch will become longer, i.e. the end of the branch is new wood, and therefore may bear fruit the following season, but the older lower part of the branch will not bear fruit again.

This determines how they are pruned. It means that, without any hesitation, you can cut away wood that is more than a year old. It is what most commercial growers do. Trees are kept compact and not a lot of old wood is left on trees. The tree will not waste any energy on maintaining old branches. It will have energy to form new ones that will bear fruit the following year.

How to prune a free-standing nectarine or peach tree:

1. Always work towards making the tree a vase shape around an empty middle.
2. You can see what wood is one year old because it is lighter-coloured than older wood. Cut one-year old wood by 50%. It will produce fruit on the remaining 50%. The aim is to get less fruit but better-quality fruit.
3. Remove all lateral branches that have already produced fruit completely or just above a promising bud close to the base of the branch.
4. Improve ventilation by cutting branches in the centre and those that begin to go inwards.
5. Cut away branches that cross each other, and that may damage each other in windy conditions.
6. Cut away diseased or damaged wood.
7. Don’t allow more than five or six main side-branches to form the vase off the central stem.

The most common type of espalier found in gardens is the T-shape simple horizontal cordon espalier. This shape is not really suitable for nectarine and peach trees because their wood is brittle and may well crack if forced to bend too much. You won’t find many successful horizontal nectarine or peach espaliers.

The espalier shape most commonly applied to nectarine and peach trees is fan-shape, also called palmette.

Prune espaliered nectarine or peach trees as follows:

1. When the tree is young focus on getting promising branches to go along the 45-degree lines, using bamboo or other straight sticks as support.
2. Cut away all branchlets that go down from these 45-degree main branches.
3. You can see what wood is one year old because it is lighter-coloured than older wood. Cut one-year old wood by 50%. It will produce fruit on the remaining 50%. The aim is to get less fruit but better-quality fruit.
4. Cut away diseased and damaged wood.

The two photos below were taken in Food Garden Group member Mandy’s garden:

Here is an example of a young tree being trained to go fan-shape:

Grafting onto a peach or nectarine tree

It was mentioned earlier that peach and nectarine trees only form flowers and bear fruit on wood that was created last year. Thereafter that wood will never be fruit-bearing again. Because of this, most peach and nectarine trees are pruned so much every season that it is difficult for grafted-on varieties to develop and become a permanent productive part of a tree. 

This is why you won’t find many peach and nectarine trees with multiple productive varieties.

One can graft other varieties onto a peach and nectarine tree, but the tree then often favours the part of the tree that you did not graft, and this will lead to uneven growth. Bud grafting in January or February is the recommended method if you want to give things a try. Strongly prune back the rest of the tree to give the bud-graft a good chance to succeed. For more on grafting see A Look at Grafting on this blog.

Thinning peaches and nectarines

Peaches and nectarines need to be thinned every season because:

• Not thinning will lead to a large crop that season, followed by a small crop the following season. It is called biennial bearing. Trees produce well one year, not much the next, then well again and so on. Early and rigorous thinning results in more even crops over the years.
• Thinning allows the remaining fruits to become bigger and tastier.
• Not thinning can ruin your tree, in particular young trees. In my garden I ruined a fruit tree by allowing a far too heavy crop to come to maturity without thinning. One day a major branch simply collapsed under the weight. The tree nearly died.

Ideally you thin peaches and nectarines when the fruit is quite small, just as they have developed pips. You can thin them later of course, but the longer you leave it, the more energy the tree spends on a lot of fruit that you are going to remove. Growers are very busy thinning early in the season. 

On my dwarf Peach tree I get clusters of five or more fruit, all on one small branch. I remove at least 3, sometimes 4 out of 5 fruit. After removing a bucket full of fruit, there is still ample left on the tree.

Imagine the size fruit you would like, and make space between the fruits, so, when fruits develop to full size, the fruits still don’t touch.

In addition to thinning fruit you may also want to thin leaves on trees that have a dense foliage – see the section Pest Control below.

Controlling peach and nectarine pests

Birds can be a devastating pest. In many gardens early netting is a must to protect fruit.

In Tasmania fungi are next on the list as pests affecting peach and nectarine trees.

The following practices go a long way towards avoiding fungal problems:

• Prune peach and nectarine trees to keep them open to sun and air.
• Prune in late summer or autumn, not winter.
• Throughout the season always remove pest-affected flowers, fallen fruit, mummified fruit and fallen branches, spoiled fruit and pest-affected leaves, as soon as you see them. Do not put them in your compost heap, but remove them from your garden.

Once you see peach or nectarine leaves affected by a fungus called Curly Leaf (see photo below) it is too late to spray. Spraying will have no effect at all.  Curly Leaf is so common in Tasmania that it is best to assume your tree will get it if you don’t spray. When it is dormant, spray the entire tree and the ground under the tree twice, with a fortnight interval, with a ready-made copper-based fungicide, lime-sulphur fungicide or Bordeaux. Do this before blossoms open in early Spring. For more info see blog post Controlling Curly Leaf on this blog.

If Curly Leaf is detected once leaves are open and left untreated, it has a debilitating effect on the tree.  Getting rid of Curly Leaf at this point is not helped by spraying.  There will be no effect at all.  The only strategy that works is removing all affected leaves, even if that results in a tree with very few leaves.  In most cases the tree will not only survive this, but form new leaves within a short period of time, leaves that don't have Curly Leaf at all.

A badly-affected tree may produce few or no fruit that season, but it is amazing how trees recover, if you persist in removing affected leaves. If it is then sprayed with curly leaf spray the following winter, it may be back to full health.

Brown Rot is another fungal pest that is common in Tasmania. It affects blossoms, leaves and fruit. It usually occurs after wet humid weather. Australia's best stone fruit is grown in warm dry areas.  Irrigation in those areas is done at ground level.

Here are the visible signs of Brown Rot:

• Brown, wilted blossoms 
• Dark, sunken spots on new wood and brown, hanging leaves on infected limbs
• Small spots of rot that enlarge quickly on affected fruits - see first photo below
• Fuzzy grey spores that cover the fruit surface
• Fruit that has shrivelled and hardened (people call them ‘mummies’) - see second photo below

In addition to the measures for preventing all fungal infections mentioned above, thinning fruit (so they no longer touch each other), thinning leaves (to allow better ventilation) and immediate removal of affected fruit are the home-grower’s best strategies to prevent or limit Brown Rot.

Some people recommend that you spray with copper-based fungicide. However, Max K recommends that you don’t do this, because the leaves may well get burned and the tree may suffer. There are commercial chemicals that will control Brown Rot, but they are not recommended if you want to grow organically.

Gummosis is the name given to the oozing of sap from wounds on fruit trees. Gummosis robs a tree of nutrients. The sap hardens into gummy yellow to orange blobs on the bark. Gummosis can be the result of damage done to the trunk of the tree by you (with a mower or other garden tool), or environmental stress (lack of water or nutrients), or a fungus named Cytospora (that came in via a wound).

The Cytospora fungus kills the wood underneath the wound, often causing whole branches to die. Infected wood and defoliation that may occur weakens the tree. If the disease infects the trunk, the whole tree may die.

If the tree is not badly affected, you may be able to limit the impact of Gummosis by :

• Pruning away the (parts of) branches that are affected
• Improving environmental conditions (drainage, irrigation, fertiliser)
• Removing darkened areas of bark plus a strip of the healthy bark around it until the wound is surrounded by a margin of healthy bark. Then paint the wound with copper-based fungicide. Keep checking the area and repeat the bark trimming if necessary. 

Harvesting and storing peaches and nectarines

For best flavour, allow peaches and nectarines to ripen fully on the tree. Peaches and Nectarines are fully ripe when the fruits separate easily from the twigs. If it is hard to pull off the tree, it isn't ripe!

When ready for picking, peaches and nectarines will feel slightly soft, and their green tinge has disappeared. 

Peaches and nectarines are best eaten on the day they are picked. They will continue ripening after they have been picked. They do not keep well. 

If you need to store peaches or nectarines, taste is best preserved if they are stored at room temperature, but this can only be done for a limited time.

Recommended further reading

The Complete Book of Fruit Growing in Australia by Louis Glowinski is an excellent book that covers a wide range of fruits and is written for Australian varieties and conditions. It has an excellent chapter on stone fruits including peach and nectarine.