(a) Weeding:
Passion fruit is a comparatively shallow-rooted plant and reacts fairly quickly to a sudden reduction in soil moisture. Except during periods of wet weather, weeds must be controlled to prevent possible shedding of leaves due to competition for water when the soil moisture is low.
When cultivating or hoeing close to the plant, care should be taken to avoid any injury to he base of the stem or the main roots. Such injuries are liable to result in basal rot and the ultimate loss of the vine. For this reason, it is preferable to remove all weed adjacent to the stem or the vine by hand. Chemical desiccants such as Gramaxone, Round-up or Dalapon can be used for weed control. Care should be taken with the foliage and stems of the plants. Shallow cultivation may be carried out in inter row areas or a sward may be allowed to develop which can be slashed as required.
(b) Pruning
Pruning is the systematic removal of dead or living parts from a plant so as to increase fruit production.
Commercial passion fruit vine-yards require regular periodic pruning. Pruning serves a variety of purposes.
Dead wood is removed and the vines are opened up to assist in disease control. Pruning stimulates the production of new fruit bearing laterals. As the fruit is borne on new wood, pruning facilitated the control of cropping and may be used, to some extent, as means of spreading or varying the harvesting period.
While the main leader of the vine is trained on the wire, the fruiting laterals are trained so that they hang down freely from the wire. Once a lateral reaches the ground it should be cut off at ground level.
To ensure the laterals hang freely, the tends which cause the vines to become entangled must be moved regularly. During the normal growing season this operation should be carried out fortnightly.
Pruning may be limited to alternate vines and cutting the hanging growths as they trail on the ground. However, more severe pruning or cutting back to the main stem is done, it is best to wait until the vines begin to active growth at the onset of rainfall. Severe pruning of dormant or relatively inactiveness may result in a severe set-back or even death of the vine. There has not been experimental evidence as to what extent pruning should be done under Uganda conditions.. But a farmer might be advised to light prune the vines during the first harvest to give rise to new lateral growth which will develop to bear fruits in the second year of cropping.
In pruning, the lateral is cut back to a newly developing side shoot as close to the main stem as possible. Once it has borne its last fruit and where no new side shoots have formed, the expansed lateral should be cut at the second fruit nodes from the main stem. Dense vines promote the development of leaf and fruit diseases such as the serious brown spot and woodiness. Brown spot is considerable hazard during periods of high temperature and high humidity.
By pruning and regular removal of dead and dried leaves, reduces the density of the vine during season of high humidity, conditions are made less favourable for the spread of the diseases.
Some advantages of Training/Pruning of the Passion fruit vine.
(1) More light and air penetrates the vine to improve fruit colouring and to create
Conditions less favourable for pests and disease.
2. Fruit picking is facilitated
3. The remove all dead, old, injured and diseased parts of the vine
4. To prevent vine over-lap
5. To encourage and stimulate development of new growth which will bear the flowers and fruits.
(c) Fertilizer Schedule
Passion fruit plants require a plentiful supply of mineral and organic materials. On fertile land, artificial fertilizers may not be needed for the first year or two but thereafter they will usually be required to maintain optimum growth and yields. Less fertile land requires the use of fertilizers from planting onwards. In Uganda experiments have produced no special recommendation as to how much fertilizer should be applied and at what time.
Experiments carried out at Namulonge Research Station to determine how NPK fertilizer influenced the yield of passion fruit did not furnish enough information to enable precise conclusions be drawn. Optimal fertilizer application appears to vary from one place to another. But well rotted farm yard manure or poultry manure can successfully be used at planting time and after every pruning. An application of about 025 kg (1/2 Lb) of single super-phosphate per plant at planting time will be beneficial.
(d) Interplanting
It is deserving idea not to waste the large spaces left in between the passion fruit rows. Annual crops such as egg plant, onions, carrots and some other short term vegetables can be interplanted with passion fruit in the first year when the fruit crop is just getting established.
Other crops such as maize, bananas, sugarcane which tend to drain the plant nutrients heavily from the soil should not be planted.
Disease and pest management
A number of insects are associated with the passion fruit plant. Some of these insects are beneficial while others are harmful. The role of the beneficial insects as pollinators is well known:
Experience in passion fruit growing at Namulonge Research Station has identified a number of troublesome insect pests of which the most important are:
(a) Mealy bugs
(b) Passion fruit mite
(c) Fruit flies and
(d) Aphids
(a) Mealy bugs:
These are small, oval, sucking insects with a cottony white waxy covering to their bodies. Infestation generally occurs on the tender floral buds and fruits. Adults and nymphs pierce the attack parts and suck the sap. The insect secrets a sugary substance over which a black coating develops. Such development interferes the food manufacture by the leaves and it downgrades the quality of the fruit.
(b) The Passion Vine Mite
The passion mite may cause serious damage to the vines. Unless damage from these mites is checked the vines may die or the growth may be so adversely affected that there is a marked reduction in fruit. To the naked eye this mite appears as scattered, reddish patches on the lower surface of the leaves along the mid-rib and veins as well as on the fruit surface. The mites attack the young leaves and suck the sap, the affected leaves are generally curled. As a result a heavy infestation may cause complete defoliation and the plant may eventually die.
(c) Fruit flies
These insect pests puncture the immature fruits while the rids are still tender. As the fruit enlarges a woody area develops around the puncture. If the fruit is still quite small and un developed, the damage may be sufficient to cause it to shrivel and fall from the vine. If the fruit is well developed, it may grow to maturity. At the time of opening, the area around the puncture has the appearance of a small woody crater which disfigures the outer appearance of he fruit but apparently does not impair the quality of the juice.
(e) Aphids
Aphids infest passion fruit and plants and suck the sap. On fully grown vines, severe damages seldom results. On seedlings, however, aphids may cause severe damage. Aphids are known to be efficient vectors of passion fruit woodiness virus, which is proving to be a serious disease of passion fruit in Uganda.
Routine Pest Control Measures
The control of pests, which attack the passion fruit, involves two basic problems:
(1) The destruction of insects which attack the plant
(2) The preservation of the insects whose function in pollination is of vital importance to fruit se.
The problem is complicated because both beneficial and destructive insects are so closely associated with the plant. The injurious insects must therefore be eliminated without destroying the beneficial ones.
An approach to this problem is the proper timing of spray applications. Less damage to the beneficial insects ma be caused when a farmer schedules his chemical spray application during periods when the pollinating insects are not active. Some of the chemical insecticides currently available in Uganda include Diazon, RogorM40 and Ambush. These can effectively be used too control most of the insect pests with instructions from agricultural extensionists. Furthermore farmers are advised to read very carefully the instruction provided on the labels since most of them covers the range of insect pests they can destroy.
PASSION FRUIT DISEASES
Passion fruit diseases were not considered to be of any serious economic importance until 1969 when the vines were planted at Makerere Farm., Kabanyolo as an estate crop. During the experiments, it was observed that one of the main drawbacks to the development of passion fruit growing could be the disease problem especially brown spot disease and woodiness virus, although the latter was not very serious at that time.
(1) Brown spot disease – Alternaria passiflorae
The disease is caused by fungus known as Altrnaria pasiflorae; this is characterized by the development of brown spots and lesions on the leaves, stems and fruits.
The attacked stem normally turns brown and this leads to ring barking. As a result the functions of the plant tissues, which are responsible for carrying food from the leaves to the roots and vice versa, are interfered with and there is subsequent dieback. As the infection progress, the spots enlarge forming a series of concentric rings and the infected leaves and fruits may fall prematurely. The vines may wither from the affected parts upwards particularly after the stem has become desiccated. The quality may also shrink and drop from the vine. When the attacks are very severe, fruits begin rotting either from the stalk or from the bottom producing a brown color in the attacked parts.
The disease may infect vines of all ages. Humid conditions, accompanied by slightly higher temperatures than normal may accelerate the spread of the disease.
Control of Brown Spot Disease
(a) Field hygiene
This involves the constant removal of all infected material, which should be burnt at least once a week. The pruning frequency should also be increased during humid periods when the disease appears to spread very rapidly.
(b) Chemical control
Besides keeping the cines reasonably exposed to the sun by judicious pruning, regular spraying is very necessary to reduce losses where the disease is prevalent. Fortnightly to monthly spraying with Dithane M45 at the rate of 30g in ten litres of water, depending upon weather conditions is recommended. If the attack is very severe spraying can even be done weekly.
Thorough coverage of the spray is very essential and, to improve this a soluble strength wetting agent (Teepol) should be added to the spray. Although there is no experimental proof, some farmers have found the use of powdered detergent like OMO to be very good substitute for teepol.
(3) Woodiness disease
Virus causes the disease. The infection is characterized by grossly misshapen fruits, which show abnormal thickening and hardening of the tissues of the fruit wall and a reduced pulp cavity. The foliage becomes mottled with dark green areas localized on the raised portions of the leaves. The leaf color between dark green and the raised areas is yellow green (mosaic appearance). The leaves are frequently misshapen and reduced in size. In some instances there is lack of growth of the terminal shoot accompanied by a bunchiness of the harsch-textured terminal leaves. The disease is one of the most serious diseases of passion fruit and may curtail the commercial life of a vineyard. Aphids spread the virus, by at the transfer of sap from diseased to healthy plants during pruning and other cultural operations.
Control Measures
Fungal sprays cannot control woodiness, it is therefore recommended that plants
Showing typical symptoms of the disease be uprooted and burnt.
Plant hygiene measures should be practiced, especially during training and pruning.
Pruning knives should be sterilized either is a solution of bleach or any other disinfectant, both before and after use. Passion fruits should never be planted again in the same field or in the immediate vicinity particularly where a severe attack has occurred.
3. Fusariam Wilt
Fusariam wilt is ye another serious disease in Passion fruit particularly the local purple and the Kawanda hybrids. The disease is soil borne, which means that the fungus lives in the soil from where it attacks the rooting system of the affected plant. The disease spreads upwards along the stem and one can easily recognize brown patches scattered on the stem. The brown patches can easily be mistaken for the brown spot disease and can only be diagnosed by an experienced person. Since the attack originates from the roots the transaction of water and minerals from the soil are interfered with, the plant starts to wither and eventually it dies.
Control Measure
There is no control of this disease once it attacks the plant. A farmer is advised to uproot and burn it and never again to plant that passion fruit which is very susceptible to this disease on the same soil.
Yellow passion fruit is somehow resistant to this disease, which Kawanda researchers are trying to use as a rootstock against this disease.
HARVESTING
Passion fruits mature in about 70 days after fruit setting when they should show a pronounced purple color. Mature fruits fall to the ground and when harvesting, vines should be shaken to dislodge any fruit, which have been caught in the foliage. Fruits should be harvested in the early morning and kept as cool ass possible during handling. During hot seasons, when temperatures are high, it is usually necessary to harvest two to three times daily to avoid fruit sun scorches. Alternatively, to reduce frequent harvesting during hot weather, a narrow strip under the rows of vines is often allowed to develop a cover of weeds and grass to protect the fallen fruits from the sun burn Care should be taken to avoid bruising the skin and the fruit should be placed not dropped into the picking container.
It is extremely difficult to determine an average yield per plant, since yields vary considerably according to climatic conditions, age and number of plants per unit area, the trellising system adopted, the pruning methods, disease and insect pests problems and the type of clone or cultivars planted. The bearing behaviour of most Kawanda hybrid passion fruit forms has a characteristic pattern, namely a small crop in the first season after planting, followed by a heavy crop in the second and possibly third season, thereafter, a fairly rapid decline.
Owing to the fact that the economic life span of this hybrid is considered to be three to five years, a yield of about 15,000 – 18,000kg/hactare could be expected in a good fruiting year.
PACKING AND MARKETING
Passion fruit is generally wet when parked in the morning. The fruit should be allowed to dry before packing, and all shriveled deformed or damaged fruit should be discarded. The fruit should if possible, be graded into “small”, “medium” and “large” sizes to facilitate packing.
Excellent opportunities have existed for increasing the export of passion fruit abroad, notably in Continental Europe. The fruits are packed in paper containers provided to the specifications of the importers. The approximate count and weight is marked on the containers.
Locally, the fruits might have several markets. The passion fruit for processing are harvested in hessian bags since the appearance of fruits in not important.
Fruits are sold almost in all consumer stores in all towns in Uganda and it is very uncommon to find vendors moving from hospital, shops or house to house looking for passion fruit buyers.