Tree Planting & Aftercare Guide

Recommendations on Tree Planting and Aftercare

The establishment of an avocado orchard is a long-term undertaking, and it is up to the
grower to ensure that their orchard gets off to a good start by purchasing high quality trees. Lynwood Avocado Nursery Ltd strives to provide superior quality trees and service at all times.

Seedling verses Clonal Rootstocks

A clonal rootstock is grown from a cutting and so is genetically identical to its parent (be it Dusa, Bounty, Latas or Duke7). We recommend using clonal rootstocks in a replant situation or when planting into heavy low oxygen soils. This potentially has great tree health advantages in the orchard, but they also require specific care to get them established.
A seedling rootstock is the result of male/female fertilization producing a fruit and a tree is propagated from the resulting seed. The root system from a seedling generally stores more carbohydrates than that of a clonal tree, but they also have a wide genetic variation (up to 400%) causing variation in the field.

Site Preparation

Site selection is of prime importance and soil should be deep and well drained. Apply base fertilizers (lime, gypsum, phosphate) according to a soil analysis. Depending on the site, pan breaking, drainage, and deep ripping (to a depth of 60 cm) may be required. As avocado trees are highly susceptible to both water logging and Phytophthora root rot disease, any practice that will improve the soils aerobic capacity and drainage rate could be the difference between success and failure. Other techniques include planting on humps (make sure the hump has a flattish top to stop the soil eroding away from the roots). In sites under high Phytophthora pressure an application of chicken manure (six months before planting), and/or an application of Metalaxyl-m 480g/l at 2.6 mils per square metre, will help to reduce disease levels.

Planting

1. Clonal trees respond very well to heat, with warm soils promoting optimal root growth. For this reason, we recommend planting between mid October and mid March. Planting outside these periods is possible but extra care to protect from frosting and maintaining leaf quality is necessary.

2. Young trees are fragile and should be transported in a covered, well ventilated vehicle. Always pick up a clonal rootstock tree by the bag and NEVER by the trunk.

3. Growers should plant the young trees as soon as possible after delivery. A long delay between nursery care and planting may cause unnecessary tree stress. If trees do need to be stored ensure they don’t dry out, by watering thoroughly a minimum of once per week.
4. Water the planting sites before planting to ensure the area is moist at planting time.

5. Drench the root ball (whilst in the bag) in a weak solution of a 40% Phosphorous Acid product, at a rate of 2 mils per litre. (Rate as per Ken Pegg) This means putting the entire bag into the solution so the potting mix is covered. Within a few seconds the bag will be drenched (no more bubbles) which both hydrates the tree totally and gives the tree some early protection against Phytophthora.

6. Paint stems with a white acrylic paint watered down to 50% strength, to protect against sunburn.

7. Dig a hole slightly deeper and wider than the bag. Put some soil back into the hole to ensure that when planted the top of the potting mix is 25mm above the surrounding ground level. (With soil pulled up to this level)

8. To remove the plant from the bag, cut the base of the bag and remove the base. Care must be taken when cutting the polythene bag to minimize root damage. Then cut a slit half way up the bag. Place the tree in the hole, fold up the cut bag and cover the exposed root ball. Slit the remainder of the bag, remove, and cover the remaining roots with the top soil, gently pressing the soil into contact with the root ball from the sides towards the centre. Care must be taken at this stage as the roots of avocado trees are very brittle and break easily. NEVER TEASE OUT THE ROOTS! Do not tamp the soil down with your feet. Position the tree in such a way that most of the branches and leaves face the direction of the hottest sun in order to protect the tree against sunburn.

9. It is very important to check the planting depth as planting too deep may result in collar rot and planting too shallow will expose the unplanted stem and prop roots to sunburn. The top of the nursery potting mix should be slightly above (25mm) the surrounding soil level. (With soil pulled up to this level)

10. Soon after planting, the young trees should be supported with a strong wooden stake. Do not push the stake through the nursery growing medium as this will damage the roots. Tie the tree firmly to the stake attaching above the side branches. Regularly check that the ties are still effective (every four to six weeks) and note that it may be necessary to loosen the ties to prevent them from strangling the tree.

11. Protect tree with a wind break box of 1.2 metre square and 1.8 metres high. This height will allow growth for the first eighteen months. Shelter should be erected so as to also protect from rabbits and hares.
We see growers using a variety of imaginative ideas for wind protection that we’d be happy to discuss with you.

12. Irrigate well the day after planting as this helps to bring the soil into close contact with the root ball.

Aftercare

1. Proper irrigation of young trees is very important! It is important to water your trees, then let them have a chance to dry out-the oxygen they get is just as important as the water they get! Lynwood uses a coarse, free draining potting mix which will dry out faster than the surrounding soils. This helps us grow great roots in the nursery, but in hot windy conditions the media will dry out within a week. If the media is allowed to dry out too much it becomes hydrophobic and can be difficult to re-hydrate. When a decision to water is made is it important to completely hydrate the growing media and surrounding area. Always be aware of where your roots are (have a dig from time to time); this is the crucial area. Tensiometres or other moisture probes are very useful for accurate irrigation scheduling. Once the roots have grown into the surrounding soil (1-2 months after planting), a 60cm tensiometre should be placed in the major root zone (to be used in conjunction with the 30 cm tensiometre) and the 15cm tensiometre can be removed. BEWARE: more trees die because of too much water than too little-they can literally drown! When we say too much we mean too often! Do not be panicked into watering because the tree is wilting during the day-the tree is simply having difficulty drawing enough water to keep itself cool. Rather examine morning or evening for a better visual indicator.

2. Mulch trees well to increase the soil organic matter, improve the soil structure, reduce evaporation and fluctuations in root temperature. Keep the mulch away from the stems to avoid collar rot; however, mulch can be used to cover newly exposed roots. Remember to also apply mulch around tensiometres.

3. Trees should be protected against Phytophthora with foliar sprays every 4-6 weeks. Use Aliette WP at 250 grams per 100 litres or alternatively use a 40% Phosphorous Acid product at 7.5 mils per litre. If the trees are planted in an old orchard, the treatment should commence 4 weeks after planting and continue until trees can be injected.

4. Foliar feed with a combination Nitrosol and Wuxal Ascafol (at label rates) every 4-6 weeks. These sprays should be alternated with the phosphonate spray (but not combined). We advise applying these foliar sprays for 6 months after planting until the roots have started to colonize surrounding soils.

5. In addition, granular fertilizers and/or fertigation can be applied to the soil 40cm around the stem, being careful to avoid contact with the stem. Apply as per consultant’s recommendations.

6. Weeding is important to prevent competition with the avocado tree roots. Hand weed an area 1 metre diameter around the trees. Herbicides are not recommended at this stage anywhere near the root zone. Avocado feeder roots can be very close to the surface and even grow up into the mulch so don’t risk exposing the tree to herbicide.

7. Regularly inspect trees for pests. Remember Grass Grub and Fullers’ Rose Weevil can start feeding on plants the night of planting. Also pay attention to Leaf roller Caterpillar, Thrips and Six Spotted Mites.

8. If planting in a cold region it is necessary to protect the young trees against frosts.

9. Remove all flowers for the first 18 months as these will compete for limited tree reserves. If trees are particularly strong (lots of vegetative growth is apparent) consider leaving the flowers and fruit on.

10. Remove any shoots that develop below the graft union as soon as they are seen to be pushing out. These are mostly found to grow in spring.

PLEASE CONTACT LYNWOOD OR YOUR CONSULTANT WITH ANY ENQUIRIES OR UNCERTAINTIES OVER THE MANAGEMENT OF YOUR SMALL TREES.