For best results, an espaliered tree should be on a wall or fence that faces north and receives at least six hours of sunshine a day, writes Gareth Carter.
Gareth Carter is the general manager of Springvale Garden Centre in Whanganui.
OPINION
Despite being cold and wet, July is a month with quite a few gardening tasks to be completed.
This is the time to do winter pruning. Trees are pruned for many reasons. Often they are practical reasons around how they impact our lives, such as ensuring a tree is not blocking light into a home, or a branch may be protruding over a driveway or constantly dropping leaves into the spouting and you decide you no longer want to clean it out.
For fruit trees, pruning is important to maximise fruit production and ease of harvest. For plants such as roses, pruning is to maintain a compact, bushy plant with a strong flowering display. If left unpruned, they tend to quickly become scraggly in growth and sparse in their floral display.
Pruning roses and many deciduous trees and fruits is best completed during the winter months when these plants are dormant and deciduous (have lost their leaves). The timing of pruning is part of the success as well as making the right cuts.
Deciduous fruit trees, such as apples and pears, and roses are best pruned during July. Any earlier, and in temperate climate areas particularly, we risk getting a warm snap that makes the plant think it is spring. The plant can then produce some new growth which risks getting walloped with a July frost.
Pruning is best completed on a day that you hang your washing outside. Pruning on warm day is not only more pleasant but it significantly decreases the risk and spread of bacterial and fungus disease.
It is important to ensure that cuts made are “clean” angled so water can not pool on the cut. I highly recommend the use of a pruning paste, such as Grosafe Organic Prune n Paste or Yates Prune Tec, to seal the cut ends of branches as this will minimise the risk of disease and insect invasions, which shorten the life of a tree.
Rose pruning is essential to reinvigorate the plant, promoting new growth and subsequent flower development. Many people struggle to know where to start when pruning. It is important to use the correct tools for pruning, as too small a tool will make any job difficult. Use secateurs for small twiggy growth, loppers for small branches and a pruning saw for larger branches.
The first step is to remove any dead, diseased and badly insect-infested branches. Where prunings are diseased, it is important to burn the prunings or send them out with the rubbish rather than composting them. Thin, weak stems should be removed with stronger ones retained. Inward-facing and crossed branches should be removed. The aim is to open up the centre of the plant to allow increased air flow, which reduces insect and disease infestation in the coming season. The remaining branches should be reduced by up to three-quarters in the case of a bush or standard rose. Climbing roses should be pruned by about half and laterals shortened by two-thirds back towards a main leader.
For a good video giving a visual demonstration on rose pruning check out www.springvalegardencentre.co.nz/gardening-info/rose-pruning/
Fruit tree pruning is primarily undertaken to allow sufficient light to penetrate the canopy area to maximise fruit set, yield and fruit quality. Here are some pointers on pruning and training some fruits.
Almonds are usually pruned and shaped as vase-shaped trees. Train the tree to three or four main limbs. Almonds fruit mainly on short spurs that bear for up to five years. Prune out about one-fifth of this wood each year. If numerous suckers arise in the centre of the tree, they can be removed in summer. Keep a strong sucker and allow it to grow if a replacement limb is required. Old but still healthy trees can be stimulated into good growth by heavy pruning.
Apples, pears and other pip fruit trees have been trained and pruned to various traditional systems for many years, including open centre/vase shape, central leader and espalier. Predominantly the central leader system is used.
Central leader system: With this system, a single central vertical trunk is selected to support the fruiting branches. The branches radiate from the main trunk and form a Christmas tree-type shape. This allows maximum sun to branches, with the lowest branches being the longest and then getting shorter higher up the trunk. Apples and pears produce flowers and fruit mainly on the 2-year-old and older shoots and on short spurs produced on the older wood. Trees need a moderate prune during the winter to stimulate growth for next season’s fruit and to maintain an open, well-balanced structure of the tree so they crop well, the fruit is of good quality and the tree’s branches are strong enough to carry the weight of a heavy crop.
Open centre/vase form: To train a tree in this way the centre leader must be removed and three to five major limbs encouraged to develop. This vase shape allows good air movement through the tree as well as good light on to the branches. This method of training is highly recommended for peach, apricot and nectarine trees.
Espalier: For best results, the wall or fence that is chosen should face north and receive at least six hours of sunshine each day. The tree needs to be trained from planting, with unwanted branches removed depending on the shape you want to achieve.
For a good video on creating an espalier check out www.springvalegardencentre.co.nz/gardening-info/espaliering-fruit-trees-video/
Research by experts has identified that the best-flavoured and biggest fruit are produced in the largest quantities on branches that grow on an angle of between 30 degrees and 120 degrees from the vertical, with the best branch angle being 30 degrees above the horizontal.
Apricots bear fruit on short spurs that form on the previous year’s growth and on older spurs that can remain fruitful for up to three or four years. Pruning is aimed at maintaining the shape of the tree and removing any old, unproductive wood. Prune and train an apricot tree to a vase shape. Protection of pruning cuts is necessary for apricots to prevent the entry of silver leaf and bacterial blast infections, which can also attack plums and cherries. Use a pruning paste over all cuts to assist healing and help prevent infection. Apricots and other stonefruit are best not pruned now but left until the summer. This will lessen the risk of silver leaf infection.
Cherries fruit on spurs on 2-year-old and older wood. Older trees should be pruned in summer to restrict vegetative growth and induce the formation of fruit buds. As a winter prune, spurs may be thinned or shortened and the branch leaders pruned to shorten replacement laterals to reduce the tree height. Upright or over-vigorous growths should be removed or tied horizontally to balance tree growth as needed. Note that the vigorous growth of cherries may be inhibited by growing them as a fan espalier. As with apricots, some summer pruning is recommended to lessen the risk of silver leaf and stonefruit blast infections. It is also advisable to construct a frame and cover it with bird netting to protect the fruit.
Peaches and nectarines bear fruit only on the shoots produced the previous year. Pruning is carried out to encourage new growth and replacement shoots to maintain a balanced and open branch framework in the tree. There are three different kinds of bud - plump fruit buds, small pointed growth buds and triple buds that have a plump central fruit bud with growth buds on either side. On branches where extension growth is required, prune back to a growth bud or, failing this, to a triple bud. Summer pruning is recommended to lessen the risk of silver leaf infection.
Basically, the objectives of good pruning are to:
Note that every time a pruning cut is made plant growth is stopped in one direction and encouraged in another. Always make cuts back to or just above some growing point – a fruit bud or strong lateral (side branch) – or to a main branch.
For a good video on winter fruit tree pruning check out www.springvalegardencentre.co.nz/gardening-info/winter-pruning-fruit-trees-video/
There are live pruning demonstrations and useful gardening talks during July at Springvale Garden Centre, 18 Devon Rd, Whanganui.
Growing great roses, free talk – 2pm Saturday, July 6.
Growing the best potatoes, free talk – 2pm Sunday, July 14.
Pruning pip fruit trees, free talk – 2pm Saturday, July 20.
How to espalier fruit, free talk – 2pm Saturday, July 27.
For more gardening information visit www.springvalegardencentre.co.nz
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