PROPAGATION OF FRUIT TREES Fruit tress can be propagated sexually or asexually. Sexual reproduction: this involves seeds produced through fertilization process. Pollen from the male part of the flower fertilizes the female part of the flower, leading to production of fruits which contain seeds, which germinates to become a new plant. Disadvantages: 1. It will not grow “ true” although the new plant will inherit many of the characteristics of its parents 2. It will be a new tree with unpredictable characteristics of its own “ Genetic variation” 3. There is a long un economic juvenile period before it comes to bearing 5 – 7 years 4. Produce big trees (huge) 5. Trees & fruits may not be attractive to the taste of growers and consumers Advantages

Sexual reproduction

1) Increasing biodiversity (much genetic variation in seedlings from the same parents) Mundelein law. 2) Increasing the richness of the gene pool – for future breeding purpose. Vegetative propagation – Asexually This involved taking a bud, cutting (or Scion), tissue from a desirable parent tree which is then grown on to produce a new plant or clone of the original – plants of same methods used for vegetative propagation genetic material in plant trees 1) Rooting (Cuttings)-A stem shoot piece of the parent plant is cut and stuck into soil. Artificial rotting homes are sometimes used to assure success eg. IBA – Indolebutyric acid (age of netting and season affects the rooting ability July & August the best true and juvenile cuttings gives higher rotting than adult cuttings). If the cutting does not die of desiccation first, roots grow from the buried portion of the cutting and it become a complete plant. This works well for some plants. 2) Root cuttings – Pieces of root induced to grown a new trunk) This method is suitable for some plants 3) Layering – refinement on roots. This is rooting a piece of wood that is still attached to its parent and continuous to receive nourishment from it. The new plant is severed only after it has successfully grown roots – It is used in propagating Lychee, “etc.

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4. Grafting The most common method of propagating fruit trees suitable for nearly all spices Grafting is the method of join two varieties, ensuring maximum contact between the cambium tissue (the layer of growing plant material just below the bark) of each so that they grow together successfully. The most common grafting techniques are:1) Whip and tongue grafting 2) Budding (3) Cleft grafting Grafting is done onto root stocks Root stocks: are varieties selected for characteristics such as: - Vigour of growth - Hardness - Soil tolerance - Compatibility with the scion, the desire variety The scion: the scion is the aerial part of the part of the desired variety. A scion is grafted on a rootstock. Advantages of vegetative propagation: • Shortening the long uneconomical juvenile stage. When adult vegetative parts are used , such a period is shortened. It takes 2 1/2 to 3 years to produce • Seedlings come true to type • Trees size get reduced 6. In vitro tissue culture. It has been successful for some fruits like banana, lychee, some temperate fruits in USA, Israel, France, Spain, S.A and Australia, but the technique is still under research in developing countries including Tanzania Seedling trees are still common in Tanzania but are gradually being replaced by budded or grafted trees.

AVOCADO GROWING Scientific name: Persia americana Miller Common name: Avocado pear Family: Lauraceae Centers of origin: Mexico, Guatemala (Central America)

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Distribution: Indigenous to Central America ( Mexico, Guatamala,) South America (Peru, Colombia, Venezuela, Chile, Brazil) the Caribbean, West Indies, Madeira, the Canaries, USA, The Dutch East Indies ( Malaysia , Indonesia, Philippines) West Africa, Central Africa, East Africa, Indian Ocean islands, South Africa, Israel and Australia. Avocado is now widely cultivated in many areas outside its center of origin. It is grown in the tropics north and south of the equator, and on subtropical regions to 43o latitude. World major producers (FAO.1990) Country Production t/ha Mexico USA 115,000 to 320,000 Brazil Dominican Republic Colombia Indonesia Haiti 40,000 to 80,000 Venezuela D.R.Congo (Zaire ) Chile San Salvador Israel Cameroon South Africa Guatemala Spain Peru Costa Rica Congo The Philippines Australia Madagascar

20,000 to 38,000

76 % produced from the Americans 11 % from Africa 9 % from Asia 2 % from Europe 2 % from the South Pacific Ecological conditions Climate: altitude from sea level to 2500 masl Longitude equator to 43o Temperature: 7oC to 20o C Rainfall: 1200 – 1600 mm

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Soils: loamy sandy, well drained soils pH : 5.5-6.6 Avocado varieties and races Avocado varieties are classified in 3 groups • Western Indian races( p. Americana Miller var. drymifolia )- grown in tropical low lowlands • Guatemala races( P. nubigenaL. Williams var. guatemalensis) grown in tropical highlands • Mexican races ( P americanaMiller var.americana ) grown in tropical highlands Varieties 220 cultivars of avocado are known, about ¼ of which are hybrids. Each cultivar is of interest in its own right. Those of great commercial value also introduced in Tanzania include: Hass, Fuerte, Weisal, Simmonds, Nabal, Peterson, and Booth 8). In Tanzania a wide diversity of local cultivars exist especially in the northern and southern highlands notably, Mbeya, Iringa, Rukwa, Tanga, Kilimanjaro, Arusha regions •

Avocado require a pronounced dry season to induce effective flowering, abundant and less staggered flowering • The three races was probably the result of selection for different climates in ancient times. It is due to this selection that avocados today present a wide range of cultivars adapted to highly diverse conditions, allowing cultivation in many different parts of the world ( tolerant to cold to extreme heat ) Choice of cultivar Given this diversity the success of a new orchard depends critically on the careful choice of cultivars and roots stocks in accordance with local conditions. • Cultivars from the Mexican race eg. Duke, Gottfried, Mexicola and TopaTopa are adapted to low to relatively cool temperatures with lower water requirement. The race grows from 1500 to 2500masl • Cultivars from the Guatemala race eg. Hass, Nabal, Gwen and Edanon require average temperatures and average water requirement. The race grows from 800 t0 1800masl • West Indies race eg. Pterson, Pollock and Waldin, require high temperatures and average water requirement. The race grows from sea level to 1000masl The tree races are completely compatible and can interbreed. Most of the widely grown commercial cultivars are inter-racial hybrids. • Guatemala x Mexican hybrids: Fuerte, Zutano, Ryan and Ettinger • Guatemala x West Indian hybrids: Booth 7, Booth 8 and Lula. Propagation by grafting technique Most avocado varieties do not come true from seeds (i.e. seed will not render the same variety). So they must be propagated vegetatively • Young vigorous growing seedling s are used for rootstocks • Terminal of the leafy shoots are used for scion material Rootstocks The rootstock which forms the root system and the base of the tree normally have the quality that forms well developed system. It must also have important characteristics such as earliness, vigour, dwarfing or tolerance to biotic stress to be transmitted to the scion 4

Scion The scion which later on forms the “head” of the tree and is the part that bears the fruit. Choice of cultivar to give the scion part should put emphasis on: - longevity - vigour - high yield - earliness - good quality Grafting techniques The technique of grafting can be acquired through practice. The grafting technique s to be used depends on local practices, preference and skills of the grafter. The major grafting techniques are: - side grafting - vertical cleft grafting* - whip or tongue grafting - top grafting • Vertical cleft grafting most commonly used as it allows very young plants to be grafted. It also provides direct contact with the primary areas of tissue growth. The rootstock is severed at the height of 15 t0o 20 cm .It then split centrally and vertically to a depth of 2 to 4 cm, depending on the size of the scion. The scion should be about 12 to 15 cm long, with 3 to 4 buds. The lower 3 to 4 cm are again trimmed into a wage shape before being inserted in the cleft. The graft is then bound with grafting tape. Planting and management of avocado trees 1.Land preparation: Avoid flat areas prone to floods. Minimum tillage is required. Prepare planting holes 1m x 1m x1m or 0.75m x 0.75 m x 0.75 m 2. Time of planting : at the start of the rain season ( SH in November / December) 3. Spacing and planting density depends on the cultivar, growth habit and climate. The following can be advocated: 8m x 6m = 208 trees/ha 7m x 7m = 204 trees/ha 6m x 6m = 277 trees/ha 4.Watering after planting is necessary. Young seedling 20 -40 lt per tree per week 5. Weed control either manually or by using herbicides. Use mulching to suppress weeds or permanent cover crops 6. Pruning: training or shape pruning consists of removing branches that are in the wrong place and trees about 4-5 m high should be pooled or headed to allow the trees to expand and reduce the tree height. Prune all shoots emerging from the rootstock 7. Fertilizer use: before planting mix soil with 1 debe FYM – and put in the planting hole. At planting add little TSP – 50 gm per hole. Apply CAN at a rate of 50 gm per tree 30 days after planting. Apply fertilizer every year during the rain season 50-250 gm TSP and 50-250 gm CAN per tree per year depending on the tree age.

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Diseases and Pests Fungal diseases: • Root rot:Causal agent : species of Phytophthora of which P. cinnamomi is the most wide spread. The fungi cause root and seeding rot. Infected trees have small yellowish leaves, sparse canopy and the end of branches are bare and desiccated, roots become dark brown and much of the tissue in rotten and crumbles. In the final stage the tree dries out and collapses. • Stem canker: causal agent P. cinnamomi. In the early stages watery blotches appear on the back. They turn dark brown , surround the stem and eventually the tree dies. • Cercospora spot ( Cercospora purpurea). Infection appear on the fruit and leaves as small irregular brown spots. The spots form entry sites for decay organisms such as anthracnose. Sray copper sprays such as Kocide for control. • Avocado sacab (Sphaceloma perseae) • Anthracnose ( colletotrichum gloeosporoides) Infection occurs through lesions caused by other organisms. The fungus causes fruit rot as the fruits ripen • Powdery mildew ( Oidium spp) . Powdery mildew covers underside of the leaves with white powdery growth. Insects Many insects attack avocado but they seldom limit production significantly. Insects are highly localized and rarely controlled unless large populations occur. The most important ones are: Avocado Looper ( Epimecis detexta) Avocado red mite (Oligonychus yothersi) Avocado banded thrips ( Selenothrips rubrocinctus) Maturity. Avocado fruit do not ripen on the tree so it has to be picked kept for 3 to 8 days to ripen and ready to eat. The interval between flowering to fruit maturity is six months. All fruits from one tree do not mature at the same time as such the harvesting operation must be repeated several times. Un-mature fruit do not ripen properly-it shrivels, become rubbery, no aroma and have a bad taste. Yield: Average yield 10 t/h (120 fruits per tree) Uses: • Table fruit Avocado (Persea Americana) is a very nutritious fruit. The large oil fraction is one of the distinguishing features of avocado containing more fat and there fore more calories than any other fruit except olives. Fresh avocado contains from 5-30% oil of fresh pulp. The high fat content of the avocado makes it a valuable source of energy, about 245 calories from every 100 g of fresh fruit. Calorific value is high but sugar content is low 3 - 10 %. Water 60-80%. Its vitamin content also makes avocado highly nourishing. The fruit is rich in vitamins A and B2 and moderately rich in vitamins C, D, E, K, H and PP. The fat soluble vitamins A,D,E, K are of particular value since other fruits contain little or none. It also contains 1-5 % protein together with niacin. The amino acid content has been reported as palmitic, 7.0, stearc, 1.0 oleic, 70.0 and linoleic, 13.0. Some selected and local cultivars have significant quantities of beta-carotene and 6

Vit.C. It is also rich in minerals (1-2 %) especially potassium, phosphorus, magnesium and sulphur. The pulp residue after oil extraction is used as stock feed • Industrial use The oil is used in cosmetics and pharmaceutical industries as raw material for making cosmetics and drugs. Other uses: -Wood for fire wood and for making utensils -Medicinal uses: Extract from the back is used as ink to mark cotton and linen textiles The fruit skin and leaves have ant biotic activity use as remedy for dysentery, the leaf decoction is taken as remedy for diarrhea, sore throat and hemorrhage. The leaves are chewed as remedy for pyorrhea. Leaf poultices are applied on wounds The seeds are roasted , pulverized and given to overcome diarrhea and dysentery, to cure dandruff and oil extract fro the seeds is applied on skin eruptions.

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