Date: November 2004
Bare rooted trees are lifted and planted in late winter or early spring (August-October), when the risk of frost has passed, to minimise stress on the trees. Lifting and planting outside this season increases the risk of tree failure. If bare rooted trees are used, care should be taken that the roots are not allowed to dry out at any stage as this will lead to root death and either tree death or slow establishment.
The root systems of bare rooted trees can be dipped in a mud slurry to keep the roots from drying out during planting.
Container grown trees can be planted over longer spring and autumn periods provided the soil around newly planted trees is kept moist. Planting trees in extremely hot, summerweather should be avoided, as high soil temperatures can damage tender young tree roots and dehydrate the tree.
The optimum times of planting are spring and early autumn. In spring, soil temperatures are rising but not high, and there is some residual soil moisture from winter rains. Inearly autumn, the tree can establish before the onset of cold winter temperatures.
Irrespective of the nursery trees used, the shorter the time period between planting and first watering the better. Ideally trees should be watered immediately after they areplanted. They do not need a large volume of water at this stage, just a very humid environment around the roots. As little as 5 L per tree will practically eliminate any planting stress and settle the soil around the root system. Any sunken areas or exposed roots that show up after the first watering should be re-covered with soil, while still maintaining the basin.
A water tanker following either mechanical or hand planting is highly recommended. After the initial watering-in, the weather will determine how soon an irrigation isrequired. In hot weather it may only be 24 hours whereas in mild weather newly planted trees might last a few days before requiring further watering.
Do not dig planting holes with an auger or post hole digger as these can glaze the sides of the hole, creating an impenetrable barrier to tree roots which w ill restrict tree growth. Make sure the tree is planted at the same depth as in the nursery or container. It is very important to keep the bud union well above ground level to avoid collar rots.
The following procedures for container grown trees should be successful:
|1.||Make provision for wind protection well in advance of planting. Container trees are particularly sensitive to the effects of wind.|
|2.||Dig the planting hole about 30 cm wide and deep enough for the top of the potting mix to be just below the soil surface.|
|3.||Remove the tree from the container by making 3-4 vertical cuts around the plastic bag.|
|4.||Carefully tease out the roots from the sides and bottom of the root ball. Pay particular attention to roots spiralling around the root ball.|
|5.||Back fill and firm the soil around the tree to remove air pockets. Water the soil and allow to settle. Complete backfilling.|
|6.||Form a basin around the tree and fill with 10-20 litres of water.|
|7.||Cut back shoots of summer and autumn planted trees to reduce the possibility of water stress.|
|8.||Place a tree guard around the trunk to protect against sunburn, sand blasting, rabbits and hares, and frost damage in winter.|
|9.||Repeat basin watering as required for the first few weeks after planting. Depending on weather conditions, watering may be required at least twice a week for the first 3-4 weeks. With container trees, it is important to ensure the potting mix does not dry out before the roots extend into the surrounding soil. A drip emitter, micro-jet or micro-sprinkler located close to each tree is particularly effective for irrigating young trees.|
Planting trees with a mechanical planter gives results equal to planting by hand and has the advantage of allowing large numbers of trees to be planted in a short period of time. It is important to have the soil worked to a reasonably fine tilth (not many clods bigger than a 20 cent piece) so that soil will easily flow around the planted tree and so that the roots will make close contact with the soil.
Container grown trees should only require minimal pruning with spring planting. Bare rooted trees may require the removal of some of the canopy to balance the root system with the shoot system (if this has not already been done by the nursery) and to assist in transport. This will reduce transpirational water loss to a level which can be supplied bythe roots of bare rooted trees.
If root systems have been damaged or trimmed, or have dried out, then the tree will have trouble supplying adequate moisture to the leaves. This will be more pronounced thehotter and windier the weather. Bare rooted trees will strike their own balance by leaf drop but preferred branches and tree structure can be retained, protected and promoted with judicious pruning at planting.
Care should be taken to avoid damage to young trees from residual herbicides from previous land use. Growing a green manure crop is recommended before replanting becausemost common residual herbicides are broken down by biological activity. Adding organic matter. in the form of animal manures will also accelerate the breakdown of these residualherbicides.
Young trees can be planted between existing mature trees either to make greater use of the orchard area or in anticipation of removing old trees. It is not recommended in thelatter case as it is better to completely remove old trees and follow the guidelines already mentioned.
If interplanting to make greater use of the orchard area, it is recommended that container grown trees be planted. They will have more extensive canopies and root systemsthan bare-rooted trees, giving them an advantage under competition from existing trees. Good irrigation is necessary to cater for the needs of the young trees rather than theestablished trees.
Consider heavily hedging the established trees prior to interplanting to reduce their competition with the new trees.