Passion Fruit Growing in Kenya T R E V O R C H A P M A N 1

A brief account is given of a minor fruit-growlng industry in Kenya. It is an interesting enterprise, because it exemplifies some problems which are apparent in fruit-growlng, especially in the tropics, including pest and disease control and commercial outlets. Marketing diflficulty is due often to the small quan- tities involved, which make sales firms reluctant to handle the product not only from the point of vlew of the initial quantity but also the possibility of repeat orders being unavailable (11) .

Passion frui t is grown commercially in several countries. Examples are Australia, Hawaii and South Africa. The two main types found in cultivation are the purple, Passiflora edulis, and the yellow-skinned, Passiflora edulis forma flavicarpa. The lat- ter is grown widely in Hawaii, whereas the former finds favour in most other countries. Apa r t from the obvious differences in skin colour, there are differences in the fruits themselves; P. edulis has a much sweeter juice which is more deeply coloured.

The frui t is used for making juice which, in some countries is relished as a beverage. The following short account concerns the production of this f rui t in the Sotik district of Kenya (latitude 0.40S; longitude 35.08E, altitude 6000 feet; average rainfal l approxi- mately 52 inches per annum, well dis- tr ibuted).

Propagation and Nurseries Passion frui t can be propagated by seed or

by cuttings, but where commercial plantings are carried out, seeding is the most common method. I f cuttings nmst be taken, however, neither the very young nor the older par ts of the vine should be used. Two internodes suffice for a cutting, and rooting nmy be en- couraged by the use of a hormone such as indoleacetic acid.

Propagation by seed is a relatively simple operation. Seed is extracted f ~ m the frui t during processing and is readily available. This is sown rather thickly on a well pre- pared seed bed, lightly covered with soil and well watered. A light grass mulch may be

1 Faculty of Agriculture, Imperial College of Tropical Agriculture, University of the West Indies, Trinidad, W. I.

Received for publication Aug. 3], ]962.

placed on the soil to prevent rapid drying out of the soil surface and to prevent wide fluctuations in soil temperature. I t is also a common practice to put a shade over the nursery beds at a height of approximately three feet.

Af ter about three weeks, under Kenya Highlands conditions, the seeds germinate, and the plants begin to grow. The seedlings remain in the seed bed long enough to de- velop two true leaves, when they are trans- planted to pots for subsequent growth before planting out in the field. Polythene sleeves may be used instead of pots or tins, and 12- inch lengths of 31,/2 inch diameter are quite satisfactory.

The plants remain in pots or tins until they are about one foot tall before being planted in the field. The timing of opera- tions is rather important, in that the plants must reach the correct stage of growth to coincide with the onset of the planting rains. Generally, planting the seed in the nursery in December will allow the plants sufficient time for development to be r~ady to be put out in the field in late March or early April . Ferti l isers are not widely used in nursery beds.

F i e l d Planting The land should be well cultivated before

planting and all weeds eradicated. In areas where African couch grass (Digitaria scalar- urn) is rife, this should be completely elimi- nated before the planting.

Planting holes are dug several weeks be- fore planting out, to accommodate the young seedlings and also to facilitate the placement of farmyard manure, if this is to be applied.

The spacing of the crop varies widely. In Austral ia and Hawaii, for example, common spaces are 10 feet X 20 feet (3, 5). In the

165

166 ECOI~'OMIC BOTANY

TABLE 1 YIELDS OF MAIZE IN BAGS (200 LBS.) PER ACRE

Superphosphate Muriate of Potash (42% P~Oa) cwts./ac cwts./acre 0 2 4 0 1 2 Mean

• 1.94(1) ~ 1.12(2) Sulphate of O 10.61 17.33 20.95 16.04 19.23 13.62 16.30 Ammonia 2 11.04 20.26 18.28 18.97 15.52 15.09 16.53 cwts./acre 4 9.31 18.63 18.11 14.92 16.38 14.75 15.35

Superphosphate 0 11.47 11.55 7.93 10.32 42% (P.oOs) 2 18.63 21.13 16.47 18.74 cwts./acre 4 19.83 18.45 19.06 19.11

1.12(2) Mean 16.64 17.04 14.49 16.06

early 1930's, when the passion fruit was first grown commercially in Kenya, the seedlings were spaced at 20 X 10 feet or 20 X 15 feet (2), and good yields were obtained; but since the incidence of 'woodiness' or 'bullet dis- ease', the tendency has been for a shorter cropping cycle and, consequently, a higher plant population to get the maximum amount of fruit off an area before it becomes ravaged by disease. The result is that the common spacing is six feet inter-row and 10 feet intra-row.

Manuring

Little benefit appears to result from either fertilisers or manures, contrary to evidence from Hawaii (3) and Australia (7), and even early recommendations in Kenya (2). This is in spite of growing the crop on phos- phate deficient soils on which annual crops, such as maize, respond well to applications of superphosphate. Table 1 shows the re- sults of fertiliser applications to maize on the type of soil under discussion.

This indicates a good response to 2 cwts. of superphosphate (42%P205) per acre on maize (81.6%), but no significant response to either potash or nitrogen.

On a trial in the same field, comparing a 'blanket' dressing of phosphate and farm- yard manure versus nil, no response was re- corded in passion fruit yields. Farmyard manure was applied at the rate of 12 tons per acre in the planting holes together with 4 cwts. of basic slag, 2 cwts. of snperphos- phate and 1 cwt. of muriate of potash per acre.

Training and Pruning Passion fruit, being a vine, must have a

framework on which it can grow. This was provided by wattle posts (Acacia spp.) cut to eight-foot lengths and sunk two feet in the ground at 20-foot intervals in the rows. Wire was fixed to the tops of the posts using staples and was kept taut by strainers placed at each end of the rows. Two leaders were allowed to grow from each seedling, the rest being removed, and sisal twine was tied to each leader and to the overhead wire to al- low the vines to grow up to it. Sideshoots were removed, until the vines reached the wires, after which no further pruning was done.

Instead of the sisal twine, sticks could have been used, and this, in fact, was a common method in the area. The crop must be clean- weeded, especially in the early stages of growth, and as many as eight or nine weed- ings may be required per annum. The use of single axle tractors for this type of work has been investigated, and these have been found to be reasonably satisfactory.

Harvesting

Generally no crop was harvested for 12 months. The first big crop was obtained some time after the passage of the first year. Two main flushes of fruit were obtained in May/June and September/October follow- ing flowering and fruit set in the drier months of the year, January-March and July (1).

The fruit was allowed to drop on the ground and was collected every two or three

PASSION FRUIT GROWING IN KENYA

TABLE 2 YIELDS OF PASSION FRUIT IN LBs./ACRE IN FIRST YEAR OF TRIAL

167

No fertiliser Fertiliser Mean

-----1505.6(1) ----- 1074.3(2) Control 22814.6 23372.7 23093.7 Metasytox sprays 0.1% at 3 weekly intervals 26538.4 24171.3 25264.8

• 24586.5 23772.0 24179.3

days; it could be allowed to remain in bags for up to a week on the farm without serious risk of deterioration before being sent for processing.

Yields vary considerably, but an average crop would be approximately 15,000 Ibs. of f rui t per acre per annum. Approximately 42 lbs. of f rui t are required to make one gallon of juice.

Pests and Diseases Passion frui t suffers from several diseases

in Kenya, but the most important by far is ~woodiness' disease. Two strains are recog- nised in the country: namely, the Trans- Nzoia and the Sotik strains, of which the former is the more aggressive (9, 10). The disease is caused by a virus identified in Austral ia as cucumber virus 1 (8.

The Trans-Nzoia strain can be transmitted by the normal tests for viruses and affects the plants at an earlier stage than the Sotik strain, which cannot be transmitted on prun- ing knives. I t is thought that the disease is aphid-transmitted, although there is no ex- perimental evidence to show that this is so in the field. I t was noticed, however, that in plantings made in open situation the inci- dence of woodiness was less than where plantings had been made in sheltered spots. On the assumption that the disease was aphid-transmitted, daily counts were made by t rapping aphids in water t raps placed in plantations in open and sheltered situations. I t was found that the maximum numbers were found in the t raps when the three week- ly moving rainfal l total dropped below two inches. I t was found also that in the shel- tered area the number of aphids caught was many times that in the open situation.

Symptoms of the disease are found on both

leaves and fruit---the leaves appear leathery and are malformed, and the frui t gradually decreases in size as the disease progresses; the ratio of skin to pulp increasing markedly. Control measures must ultimately depend upon resistant var iet ies-- the spraying of systemic insecticides on the crop itself is not likely to be of any long term advantage; at most, it can only slow down the spread of the disease and even this is unlikely. In the trial quoted in Table 2, spraying with Meta- systox had no significant effect on yield, and observations on the trial showed that woodi- ness was beginning to appear regardless of treatments. The other main disease is brown spot (Alternaria passiflorae), which can be controlled by the use of copper sprays (4). This disease can reach alarming proportions, completely defoliating the vines in a severe attack.

Processing and Marketing The processing of the frui t is relatively

simple and does not require expensive ma- chinery. Fo r juice production, the pulp must be extracted from the skin, and then the seed must be separated from the juice. A simple 'home made' machine has been developed for the first process, and it works extremely well. The last stage is accomplished by means of a centrifugal type of machine; the pulp being fed into a revolving cylinder which is perforated to allow the seed to be retained, while the juice passes into an outer jacket and is run off to be pasteurised and canned. A continuous process centrifuge has recently been developed in Hawaii (6). All par ts of machinery in contact with the juice are made of stainless steel.

~1arketing is difficult because of the small quantities produced, but there seems no

16~ E('.ONOMIC BOTANY

doubt that, if a market could be obtained, production would increase considerably. I t is the initial breakthrough that is required to cm/ble this small industry to im'rease. The industry in Kenya has had a somewhat chequered c~|reer in that it was just get t ing well est~/blished in one or two areas when the war broke out in 1939. The incidence of disease and other factors, such as marketing, delayed the resumption of its cult ivation un- til recently, when the search for cash crops as al ternatives to maize, in part icular , was initiated. Whether or not the industry will grow depends for the present on this ques- tion of market ing, because, with the mild str~lin of the virus in the main growing area, it is possible that economic crops can be pro- dueed for three years before the vines finally succumb to the disease. As stated above, the long term answer must lie in finding resistant varieties, and this is being actively pursued at the present time.

Acknowledgments

The permission of the Director of Agricul- ture of Kenya to publish the figures in Tables 1 and 2 is gra teful ly acknowledged. These results were obtained while the author was an Agr icul tura l Officer in the Kenya De- par tment of Agriculture.

References 1. Akamine, E. K. and G. Girolami. Pollination

and fruit set in the yellow passion fruit. Hawaii Agr. Exp. Sta. Tech. Bull. 39. 1959.

2. Anon. The culture of granadillas (Passi- flora cdldis). E. Aft . Agr. Jour. 1: 384. 1936.

3. Anon. Passion frui t culture. Univ. Haw:lii Ext. Circ. 345. 1954.

4. Anon. Brown spot of passion fruit. Agr. Gaz. N. S. W. 67: 490. 1956.

5. Ebbott, I. E. Passion fruit growing in N. E. Victoria. Jour. Dept. Agr. Vic- toria. 46(11): 508. 1948.

t;. Kinch, D. M. A continuous process centri- fuge. Trans. Amer. Soc. Agr. Eng. 2(1) : 52. 1959.

7. Levitt, E. C. and K. D. McGillivray. Grow- ing passion fruit. Agr. Gaz. N. S. W. 69:518 and 601. 1958.

8. M:Jgee, C. J. Woodiness or mosaic disease of passion fruit. Agr. Gaz. N. S. W. 59: 199. 1948.

9. Nattrass, R. M. A preliminary note on the woodiness disease of passion fruit in Kenya. E. Afr. Agr. Jour. 5: 130. 1938.

10.-- . Further notes on the woodiness dis- ease of passion fruit in Kenya. E. Aft. Agr. Jour. 6: 54. 1940.

11. Stambaugh, S. U. Tropical fruit products of the Caribbean area. Proc. Amer. Soc. Hort. Sci. (Caribbean Region) 3: 52. 1959.