Caring for New Trees

The way in which trees are cared for will have an important effect on the establishment and future production of the tree.

The key to successful tree establishment lies in keeping the young tree from suffering dehydration, either by adding moisture, or by removing top growth to balance water loss with the capacity of the reduced root system to supply the tree's water requirements. Important factors to be considered include care during transit and storage, soil preparation and planting techniques. Moisture plays a critical role in the time between lifting and final planting. To further ensure optimal tree production, consult us regarding which varieties to grow. We have information and experience about the combination of varieties and rootstocks that will prosper in your particular location.

In Transit 

Trees should never be allowed to dry out at any time between lifting and planting. Trees must be transported in closed containers, with moist roots protected by suitable packing materials, e.g. straw or shredded paper. If the trees are not in a closed container, completely cover with tarpaulin and have suitable packing materials around the roots. To avoid the roots drying out there should be no air leakages or drafts under the tarpaulin. The trees will need protection against freezing if in transit during very cold weather. Check trees immediately on arrival and communicate with the freight company and us if there is a problem. Trees, which arrive in a dried out condition, may be resuscitated by total immersion in a dam or creek for 18 to 24 hours to rehydrate. Do not leave trees in water for any longer than 24 hours, as there is a risk of drowning the trees. This is particularly important with stonefruit, as more than 24 hours immersion can induce Cyanogenesis within the tree.

 

Storage

Ideally, plant all trees as soon as they arrive. Often weather or soil conditions are not conducive to planting, making storage necessary. There are three storage options available:

  1. Outside
  2. Inside
  3. Cool storage

1. Outside

The trees are placed into a sawdust, sand or a fine tilth soil bed. The storage area should be located out of both wind and direct sunlight. For example, the south side of a shed, or in the shade of a shelter belt with access to a hose for daily damping down. Key points to note are that the storage media around the roots must be well tamped around the roots to exclude any air pockets, which may cause root drying. If the trees are going to be stored for more than 2 or 3 day, the bundles should be cut open and the trees spread out so the roots have good contact with the storage media. To ensure the roots are moist, water into the root media beds with a sprinkler or hose. Select a free draining storage area to avoid waterlogged soil (in the case of heavy rain or over watering). At this stage, the root system will be inadequate to supply the requirements of a large tree, which will continue to transpire and lose moisture even though dormant. It is therefore necessary to rehydrate the tops by moistening them. Damping down with a hose to wet the bark but not saturate the roots one or two times a day will keep the trees in good condition.

2. Inside

Draught-proof sheds are satisfactory for 2 to 3 days storage, without the need to plunge the roots into sawdust or similar. Switched off cool stores are ideal. Closely pack the tree bundles, cover with hessian sacking or similar material. Keep the covering moist at all times by sprinkling water over lightly, up to 4-5 times daily. This method is not recommended for stonefruit due to bacterial problems of spot and blast, which favour these conditions for the spread and development of infection.

3. Cool Storage 

Longer-term storage is more difficult, less desirable and rarely used in New Zealand. Advice should therefore be sought prior to the use of this option. Trees must be fully dormant when they go into storage if they are to be held beyond the normal time of bud break. Key points are to store the trees upright in bins or on the floor with damp sawdust tightly packed around the roots as described for outside storage. Exposed aerial surfaces need damping down once or twice a day, taking care to not waterlog the roots. Optimum cool storage temperatures depend on the length of time the trees are likely to remain in storage. The presence of ethylene from stored fruit can injure trees so trees cannot be stored for any length of time in stores, which have fruit in them or have not been properly vented.


Preparation

  1. Soil Conditions
  2. Slurry Dipping
  3. Soil Sterilisation
  4. Monoammonium Phosphate Fertiliser (MAP)
  5. Planting
  6. Time of Planting
  7. Planting Depth
  8. During Planting
  9. After Planting
  10. Common errors to avoid

Soil Conditions

For satisfactory tree establishment the soil needs to be moist but not wet, and tilth enough to exclude air pockets around the roots of newly planted trees. When soil conditions are dry the trees must be watered in at planting. This needs to be done with targeted water application. For example, 15-20 litres per tree directed at the roots. If the soil is very dry and watering the trees in at planting impractical, consideration should be given to irrigating the planting area a few days before planting.

Slurry Dipping

A clay slurry dip will give excellent protection against drying of the roots. This would be a practical method of protecting the roots of smaller numbers of replant trees. 'Alliette' or 'Ridomil' may be added to the dip to give additional protection against Phytophthora.

Soil Sterilisation

In replant situations where sterilants have been used, aerate the ground to remove traces of fumigant. For fumigation to be effective and dangers from fumigant residues eliminated, aerate while soil temperatures are warm (16-27o C).

Monoammonium Phosphate Fertiliser (MAP)

MAP should never be placed in direct contact with roots. No more than 100g per tree should be used near the tree at any single application. Where tree planting machines are used, MAP should either be strip incorporated before planting, strip broadcast ahead of the planter or surface sprinkled in the approved manner for fertilisers after planting.

Planting

Damaged roots should be removed prior to planting.

Time of Planting

High young tree performance is dependent on the time of planting, which ideally should be before mid July. Early planting enables root establishment and root growth to occur before leafing out. This means that a larger top can be retained as roots lost in the replanting are replaced prior to bud break. Late planting into dry soils or planting of desiccated trees often results in trees failing to leaf out completely. If this occurs, photosynthates are not being produced and translocated to generate new root activity. Once the tree exhausts its stored reserves, it will sulk and may even die.

There are a number of inter-related factors that affect whether trees should be transplanted during autumn or spring.  Essentially it depends on balancing the outcome you wish with your skills.  See further information Autumn Planting vs Spring Planting here.

Planting Depth

The depth of planting will depend on soil type, height of budding and rootstock. In thin soils with impervious subsoil, the root system should be planted in the topsoil above the impervious layer. If the topsoil is very shallow, it should be ridged up to allow sufficient topsoil depth for satisfactory planting depth. For dwarf rootstocks such as MARK and M26, the bud union should be as close to soil level as possible, but still sufficiently high to avoid scion rooting. This minimises the burr knot problems these rootstocks are prone to, and gives more uniform tree vigour. When using standard rootstocks (e.g. MM106 or M793) on free draining soils, planting should be as deep as possible after allowing 150mm of rootstock stem between soil and bud union.

During Planting

Particular care is needed to avoid root bending or twisting, especially where planting machines are used. Shoes on mechanical planters must be of sufficient size to take the root system without root bending. The hole must be large enough to take the root system, and any glazing around the sides of the augured holes must be removed. In clay soils the hole must not be filled with lighter textured soil, which will allow water from the surrounding soil to drain into the hole.

After Planting

Trees lose water during winter even though they have no leaves. The lose water through the lenticels on the bark. Frosts also desiccate the trees. Therefore the trees need to be 'watered in' and watering continued throughout the winter into the growing season. This is very important and should be carried out even in colder climates. Take care not to over-fertilise trees after planting to avoid fertiliser burn. Surplus branches or feathers should be removed immediately after planting. Protect all pruning wounds against silver leaf infection and dehydration with a suitable wound protectant. 

Common errors to avoid

Staples vs. Tying or Strapping: We have noticed that some growers use impact driven staples to attach the trees to wires. This appears to be causing a dead area in the bark and cambium and as the tree grows, a flattening of the stem of the tree with a large dead area that definitely effects the growth of limbs and productivity above the staples and also appears to be a perfect site for saprophytic fungi. Tying or strapping the tree is a better technique.

Spray Guards: Spray guards are often necessary for pest control and to avoid the absorption of glyphosate into young trees if spraying is not done in ideal conditions or with care. Certainly the trunks of young trees, especially young stone fruit, should not be exposed to glyphosate. Spray guards act as mini glasshouses and greatly modify the temperatures within the area of the guard. In Central Otago they must be removed from young trees (especially cherry ) during late summer as the development of frost hardiness of the tree under the guards is supressed by this modified climate. Remember that spray guards stop all spray, so that suckers do not get srayed when the tree is being sprayed. When removing suckers inside the guards, the wounds must be painted to avoid invasion of fungi and bacteria.

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