The tamarillo (Cyphomnadra betecea (Cav.) Sendt) is a member of the Solanaceae family, along with the potato, tomato, eggplant and capsicum peppers. The genus Cyphomandra contains about 30 species of soft-wood shrubs, all natives of Central and South America and the West Indies.
The tamarillo was first introduced into New Zealand from Asia in the late 1800s. Only yellow and ‘purple’ fruited strains were produced from the original introductions. The red types were developed by an Auckland nurseryman during the 1920s from seed sourced from South America. Other red strains, developed independently, appeared soon afterwards. Since then, continued reselection of these original red strains by growers has led to the large, high quality varieties available today.
On 31 January 1967, after almost unanimous agreement amongst growers and with the consent of what was then the New Zealand Department of Agriculture, the fruit’s commercial name was officially changed from tree tomato to tamarillo. This change was made to provide a more appealing and exotic name, especially for export promotion and also to avoid any confusion with the common garden tomato, Lycopersicon esculentum, to which the tamarillo bears only a superficial resemblance. The flavour and general uses of the tamarillo are, however, quite different from those of the ordinary tomato.
The tamarillo is an extremely nutritious fruit, containing good quantities of several important vitamins – A, B6, C and E as well as being rich in iron and potassium and low in sodium. An average tamarillo contains less than 40 calories.
The tamarillo is a subtropical shrub and is extremely frost intolerant so its growth is restricted to those areas where frosts are infrequent and only slight.
The plant prefers a light, well-drained soil. It is highly intolerant of excess soil moisture and rapidly succumbs in waterlogged soil, conversely its large, soft leaves and shallow rooting system cause it to react unfavourably to drought conditions – it needs ample moisture during summer.
The tamarillo’s large leaves and extremely brittle wood make it very prone to wind damage. When heavily laden with fruit the branches break off easily, even in quite light winds. This is especially apparent on both pruned trees heavily laden with large fruit and on unpruned trees. Tamarillos produce their fruit on the current season’s growth. If trees are left unpruned, the new fruiting wood gradually extends from the ends of the branches and the laterals leaving the centre of the tree more or less barren. Frequently the weight of the fruit produced on the end of a long, weak, spindly branch or lateral causes it to break. Pruning is therefore recommended.
Pruning can commence in early spring (August onwards) once the danger of frosts is past and the majority of the previous crop has been harvested. This may continue through November and even into December but will vary from district to district, and from site to site within a district. However, most blocks are pruned by the end of October.
The timing of pruning influences the time at which the following year’s crop will mature. Pruning in early spring, or not pruning at all, normally results in early maturity. Delaying pruning until November results in a later crop due to a delay in spring shoot growth upon which new flowers will be borne. Flowering generally begins 10 weeks after shoot emergence. Fruit matures from fruit set after a fixed period so the delay in the onset of the harvest season due to later pruning is approximated by the delay in the timing of pruning.
Light pruning (up to half of the old canopy) gives rise to weak regrowth that quickly branches and sets flowers, and in turn leads to a heavy, early maturing crop of small to medium sized fruit.
Hard pruning (back to near the original forks of the tree) gives rise to vigorous regrowth and usually a smaller crop of larger-sized fruit that matures a little later than that of trees pruned lightly at the same time (Figure 1).
Figure 1: Fruit size response to the degree and timing of pruning in mature tamarillos.
Tamarillo flowers are produced in successive trusses or inflorescences
like tomatoes. Flowers are functionally male and female and are self-fertile,
thus only one tree is required in a garden. Pollination is carried out
by honey and bumble bees. Lewis & Considine (1999) have studied flowering
of tamarillos in some detail (1999) and the following is a summary of
The production of excessive amounts of flowers may offer the tamarillo
some advantages in its native habitat. This strategy may ensure some fruit
sets if pollinators are not present at specific times, or if fruit set
early in the season do not develop.
The major diseases of tamarillos are tamarillo mosaic virus, powdery mildew and sooty mould. The major pests are whitefly, aphids and green vegetable bug.
Six species of aphid are known to attack tamarillos but by far the most important of these is the green peach aphid (Myzus persicae).
It is most important to control aphids. Although not particularly deleterious to plant growth, the main concern is their role as the carriers and transmitters of viruses in tamarillos. Aphids are potentially present on tamarillos the whole year round but are present in greater numbers from spring to autumn. Their peak flights occur in early spring, late summer and autumn.
Ladybirds feed on this pest so practices that encourage the presence and activity of ladybirds will prove beneficial.
Tamarillo mosaic virus (TaMV)
Symptoms of TaMV are a mosaic mottling on the leaf, and on the fruit
skin unsightly irregular blotches which are a darker red than the normal
skin colour for that cultivar. No symptoms appear inside the fruit and
eating quality is not affected. On golden tamarillos, the darker red blotch
is most unsightly due to the paler background colour typical of this class
Fletcher, W.A. 1979: Growing tamarillos. Bulletin/New Zealand Ministry
of Agriculture and Fisheries No. 307: Wellington, New Zealand. New Zealand
Department of Agriculture. 27 p.