Crop management

1. Pollination

Avocado flowers need to be pollinated before the fruit will set. Flowers are either male or female, so pollination requires transfer of pollen from a male flower to the stigma of a female flower, even when a variety is self fertile. All varieties yield better when pollen comes from a different variety, and this even applies to Hass, which is sometimes considered to be highly self fertile. Ettinger is a particularly good pollinator for Hass. Pollination is usually carried out by insects, and if they are experimentally excluded from flowers, no fruit sets. Honey bees have been found to be the most important pollinators, even when wasps and flies are abundant, so the presence of honey bee hives in or near the orchard is recommended.

2.Tillage, weed control and cover crops

During the early years of an orchard it is desirable to plant a cover crop to protect and maintain the soil until the trees can cover it with shade. Such a crop must not, however compete with the trees and must be restricted to the strip between the tree rows. The area around the base of the tree must be free of grass and other weeds and. If possible, this area should be covered with an organic mulch.

3. Training and pruning

Pruning during the first years is desirable to encourage lateral growth and multiple framework branching. In order to reinforce this shaping of the tree, sucker growth must be continuously stopped by removing all shoots originating from below the grafting joint. These shoots grow from the rootstock and are not part of the grafted cultivar.

Training a tree means creating a strong central shoot from which extend spaced side branches at the desired height and the creation of a bare main trunk about 50 - 70cm in height. Keep in mind that excessive pruning of a young tree in its juvenile stage will definitely delay the productive phase.

In later years, pruning is mainly undertaken to influence the size, quality and quantity of the fruit. It includes the removal of undesired shoots inside the canopy, the pruning of broken or diseased branches and the shortening of those touching the ground. The best time to prune is during the dormant season.

4. Fertilization

Young trees must be fertilized very judiciously since their roots could easily be burnt. Avocados can take up and utilize adequate amounts of essential elements without much fertilization, provided a suitable fertile plot has been chosen for planting. However, manure applications of 50 kg per tree per year are common.

Table. Nutrients recommendation per one avocado tree (g/year)

Age	N	P	K
1	42	22.6	75
2	84	45.2	150
3	126	67.8	250
4to5	168	101.7	300
6to7	224	135.6	400
8to9	280	169.5	500
10to12	336	203.4	600
Max	420	203.4	750

Zinc: Most soils are either naturally low in zinc or the zinc is not available. The following quantities should therefore be applied annually: Zinc oxide at 200 g/100 l water

Boron: Many avocado orchards are also low in boron and the trees should be sprayed every year with 100 g borax or 75 g Solubor/100 l water.

Table. Fertilizer recommendation per one avocado tree (g/plant) per year

Year	NPK (17-17-17)	Urea (46-0-0)	KCl (0-0-60)	Zinc	Boron
1	133	42	87	Zinc oxide at 200g/100L of water, to be applied annually	100g borax/100L of water, to be applied annually
2	266	84	175
3	399	127	304
4 to 5	598	144	331
6 to 7	798	192	441
8 to 9	997	240	551
10 to 12	1,196	288	661
Max	1.196	471	911

Time of application: 2 equal applications in beginning of season A and B.

5. Irrigation

Irrigation will be beneficial to plant growth and crop yields during prolonged dry periods. Avocados are sensitive to moisture stress. Critical stages of moisture demand occur during flowering, fruit-set and fruit development. Irrigation at 3 weeks interval resulted in early maturity, increased fruit size and oil content. In dry period, water is given at 10 days interval. Sprinkler irrigation is better than flood system as avocado plants have shallow root system and cannot stand water logging. Drip irrigation gives better results than other irrigation methods.

6. Intercultural and intercrops

Avocado orchards should be kept free from weeds. Shallow cultivation is preferred, otherwise it will damage roots. Mulching with grasses and leaves can be done as a practice that will impede weed growth and conserve soil moisture. Weedicide can be applied annually to check weed growth. Shallow rooted and leguminous crops are grown as intercrop in avocado plantations during first few years.

7. Thinning fruit

Larger fruits are preferred by the market, but when a tree bears a very high number of developing fruits they tend to be smaller. Removing (thinning out) some of the developing fruits will tend to produce the desirable heavier avocados. This process also discourages biennial bearing, which is a tendency for some trees to produce bumper crops one year and poor ones the next.