PINEAPPLE PRODUCTION Introduction The pineapple is a tropical and subtropical fruit grown in many countries in Africa. In Uganda it is mainly grown south of Lake Kyoga and western Uganda. Ii is a tradable crop and generates reasonable income. It is used as a fruit as well as for producing juice. It is also used for making jam. In addition it contains a protein digesting enzyme bromelain. Therefore it can be used as a meat tenderizer. Leaves are used for making ropes and coarse cloth. Waste products from the juice canning industry are used as animal feed. Ecological requirements Pineapple is fairly drought resistant but for high yields a well distributed annual rainfall of at least 1000mm is required. A regular supply of soil moisture is essential. Medium altitudes of 1350-1750m above sea level are the best. Below 1350m the fruit has little fibre, leading to a mushy fruit. The fruit also contains too much sugar leading to a bland taste. At high altitudes growth is slow and the fruit contains much acid. Deep sandy loams with a lot of organic matter are ideal. Other soil types can be used as long as they are not water logged and organic matter is added. Types (Cultivars) Cultivars: Smooth Cayenne is by far the most important pineapple cultivar throughout the tropics, the leaves are almost spineless except at the apices. Queen is still grown in some areas. This cultivar produces smaller but sweeter fruits than smooth cayenne, but the leaves are spiny and difficult to work with. The Red Spanish is a semi spineless cultivar grown mainly in West Africa and South Africa. Its fruits are intermediate between those of smooth cayenne and queen but are of better quality than those of smooth cayenne. It has some resistance to mealybug wilt disease. Management Practices Propagation 1
Pineapples are propagated vegetatively by planting crowns, slips or suckers; although seed can be used in breeding. Pineapple fruit and propagation materials Tissue culture can also be used. The propagules are extremely resistant to desiccation and root readily when planted in the nursery or in the field. By planting various types of propagules the period of harvest can be extended since offshoots (suckers) fruit in about 17 months, slips in 20 months and crowns in 22-24 months. Planting takes place at the start of the rainy season or it can start any time in the irrigated areas. The propagule stem should be allowed to air dry for one week prior to planting so that the callus layer is formed over the damaged tissue thereby making them resistant to disease infection after planting. Scaly leaves should be removed from the lower portion of the propagule stem to expose the primodia (future roots). If this is not done, establishment will take long. Spacing Some farmers use double rows, others 3 rows, others more. For practicle purposes, however, pineapples are generally planted in double rows spaced at 2 ft (60cm) between the rows, 1 ft (30cm) between plants and 4 ft (120cm) between adjacent double rows. This gives an approximate plant population of 36,250 plants/ha. 2
Field layout and spacing specifications The rows are marked using pegs, string and tape. Holes are dug shallowly (7-10cm deep) using a small hoe or just insert a large stick in the ground and only the pedal part is planted and firmed. The propagules are planted on a level ground and later ridged. Ridge planting helps provide a deep bed for a better root growth and also creates water between the double spaces or draining away excess water in water logged areas. Fertilizers Nitrogen is the nutrient most used by pineapples. It can be applied at the rate of 50 kg per hectare top dressed one month after planting. Additional 41-670 kg per hectare applied three to six months interval is recommended before maturity. An additional 200 kg per hectare of nitrogen can be applied to each ratoon crop. Where phosphorus is lacking, plants have narrow brittle leaves with a dark red color spreading the entire leaf. Potassium deficiency produces a poor quality fruit; few suckers and slips will be formed. The best method of application is preplant broadcast mixed with the top 15 cm of soil. Iron deficiency is identified by a general chlorosis (pale yellow or yellow-white colour) similar to that typical of nitrogen deficiency. Zinc deficiency causes a mottled yellowing of the leaves. Weed Control Weeds can be controlled in three ways notably by: hand, use of mulch and use of herbicides. To obtain maximum production, perennial weeds should be dug out prior to planting and all newly germinating weeds should be controlled while in seedling stage. If a crop is planted with pineapples, weeding should be done in the early stages. It is advisable that after harvesting the intercrop hand weeding should not be continued. The pineapple has a shallow root system which should not be disturbed. Different materials can be used for mulch for example, dry elephant grass, leaves or other organic materials such as chopped debris from previous pineapple crops. They are beneficial in 3
restricting weed growth, decreasing erosion, adding humus and nutrients to the soil and conserving moisture. However, the common and effective mulch is coffee husks. A good layer should be maintained for effective weed control. Higher yields of good quality fruits are obtained. Pre-emergence herbicides like HYVAR-X (Bromacil) are applied soon after planting and the crop remains weed-free for about 12 months. No crop should be interplanted as it will be killed off by the herbicides. Post emergence herbicides applied when the weeds are growing actively are also available e.g. GESAPAX and GESATOP. Harvesting Pineapples should mature 15-24 months depending on the planting material used. In harvesting it is best to cut, rather than to break the fruit by the stalk. With adequate management, the main crop should yield about 70 tonnes/ha, while ratoon crops yield on the average 50 tonnes/ha. At least two ratoon crops can be grown after the plant crop. Stripping for ratoon crops A number of ratoon crops can be taken if management is good but fruit size decreases. They give profit to the undertaking as the main crop plant pays for crop establishment. Stripping involves the removal of all slips and all unwanted suckers. Only one sucker should remain as the basis of the ratoon crop. It should preferably arise from below the ground. Stripping should start at around the time of harvesting. If correct sized suckers and slips are needed as propagation materials from the main crop, two to three operations at monthly intervals will be needed. Insect Pests and Disease Control Nematodes, particularly the root knot nematode may become a problem and is a serious pest in many pineapple growing regions. Soil fumigation (if funds allow) should be carried out to reduce nematode damage. Furadan, Nemacur, or Temik can be used. Infestations by pineapple mealy bug result in yellow spots appearing on the leaves but, more importantly the insects spread black spot (Penicilium funiculosum and Fustrium moniliforme). Insecticides such as Salut, Decis, Rogor etc. can be used to kill mealybugs. Dipping pineapple planting material before planting in a fungicide-insecticide solution can help to eliminate them e.g. mix about 30 ml sumithion in 20 litres of water. 4
Wilt of leaves due to infestation with mealybug Thrips may be important as vectors of yellow spot virus which causes deformed fruits or the production of fruits with several dead fruitlets. Hosts of the virus other than pineapple are weeds such as Black jack, Datura stramonium, Emila sonchfolia and vegetables such as pepper, tomato egg plant, broadbean, spinach and peas. Yellow spot of pineapples is usually more severe when these plants are grown nearby. Yellow spot virus spread by thrips Heart and root rots caused by the fungus Phytopthora cinnamon and P. parasitica are sometimes serious. The leaves rot from the tips and the base of the heart resulting in an offensive odour. It is common in young plants of 3-8 months. Splashing rain, irrigation water and biting insects act as agents to spread disease. For effective control of the disease one has to ensure good drainage, avoid overhead irrigation and control insect pests. Soil should be prevented from entering the hearts by covering lightly with grass and removing the grass later. Planting materials can be 5
dipped in copper fungicides before planting or use resistant plants. Fungicides can be used to control any fungal complications. Heart rot caused by Phytopthora cinnamon Pink disease, caused by a bacterium transmitted to ripe fruits by insects causes a browning of canned fruits but can be prevented by early harvesting. The disease enters fruits via wounds and causes the fruit to ferment, producing a yeasty, alcoholic smell and undesirable off-flavour. Control is by careful handling to prevent injury and by sorting so that injured fruits are consumed or processed rapidly and only uninjured fruits are sent to the market. 6