Custard apples are an unusual fruit, which once tasted will always be pleasantly remembered. The large green skinned fruit, about the size of a grapefruit, looks anything but appealing. However, any initial disappointment is quickly forgotten when you dip into the fine custard-like sweet flesh. The fruit is virtually unknown on Perth markets, most people who have tried it have done so on trips through South-East Asia. Commercial plantings of Custard Apples have now taken place in Queensland, Northern NSW and Carnarvon in WA.
The suitability of the Perth Climate
Custard Apples originated in the cool mountainous areas of South America and are now grown throughout the tropical areas of the world. They can succeed very well in the metropolitan area where a fairly controlled micro-climate exists. In particular they need to be protected from drying easterly winds, probably the greatest requirement for growth and fruit set. They enjoy a high level of humidity and this can be achieved in a small garden with plenty of summer moisture, especially from overhead sprinklers and heavy mulching with organic material. Custard Apples also need protection from frosts, particularly while they are young. Mature trees can stand temperatures down to around minus 3c but a heavy frost can kill a young tree.
I’ve seen a young four metre high tree in the Perth suburb of Kensington with a crop of about 30 fruits. Custard apples are normally semi-deciduous, meaning that they lose their foliage in early spring before flowering. In cooler situations, in certain backyards they can lose all their leaves throughout winter.
Custard Apple Varieties
Seedling Custard Apples do not produce satisfactory fruit and take many years to produce any fruit at all. As such they are an unreliable proposition for the home gardener and the commercial grower. Grafted trees bear within about three years from planting and the fruit is much superior to that of the seedlings. There are two main varieties – African Pride and Pinks Mammoth. African Pride is a compact tree, will bear in its third year after planting and is more tolerant of the cold and crops on Autumn. Pinks Mammoth is a big open tree and takes up to six or seven years to produce a full fruit set. The fruits are bigger and more irregular in shape than African Pride and the quality is clearly superior.
Position is most important. Custard apples need to be planted in a sheltered position facing north to north-west to maximise winter sunshine. You can plant your tree near a cluster of other trees for protection, not only from wind but also frost. Soil preparation is essential, particularly for our sandy soils. Custard Apple trees need plenty of well-rotted animal manure such as chicken, cow or sheep incorporated into the planting hole. Mulching is essential, to not only improve the humidity situation, but also to insulate the plant from rapid changes in moisture and root temperature. Irrigation in summer is particularly critical. The trees should never dry out and need to be watered even when established, at least twice a week. During very hot
Weather, when the temperature reaches 40c they need watering daily.
It is recommended that you don’t apply any fertilisers to your new plant till it shows signs of a successful take. This usually occurs two to three weeks after planting, depending on the season. The recommended feeding is at six to eight week intervals during the growing season ‘from September to April with Nurserymen’s Brand General Purpose Garden Fertiliser or NPK Blue – both have a balance of major nutrients required for growing and successful fruiting.
It is important to prune young Custard Apple trees to form a vase shape. Their natural tendency is to produce a strong leader and a conical shape. When buying your custard apple choose a plant with two strong shoots. Once these have reached 60 to 70cm in length take out the tip of each shoot with a pair of secateurs. Continue to take out these tips on subsequent growths when they reach that size. This will result in an open, spreading frame for your tree, enable it to support a big crop and allow light into mature the fruit. Mature trees should be pruned lightly in December .to promote young flower growth. Custard apples will fruit on old as well as new wood.
Fruits take up to six months to mature on the tree after setting. Choosing the correct moment to harvest the fruits requires same experience. However, one thing to look for is the skin between the main segments of the fruit, which changes from a green to a cream colour. Cut the fruit stem with a pair of secateurs, leaving a 3 to 5cm stub of stem on the fruit. This helps to prevent the entry of disease spores. The fruit now needs to be left for a couple of days at room temperature to soften before it is ready to eat
What can go wrong
1) A LOW FRUIT SET ON HOT DRY CONDITIONS – you can overcome this problem by hand pollinating individual blooms. Use a small paint brush to transfer the golden grains of pollen from the male part of the flower to the sticky receptive female parts of the flower.
2) SCALE INSECT INFESTATION – this is quickly picked up by the presence of a black sooty mould on your tree. This particular mould is attracted by the exudation of the scale insect. Spray your plant on a cool day with Malascale which is a mixture of malathion and white oil. It is important to follow up this initial spray ten days later with a second application.
3) COLLAR ROT – it is important to avoid this problem early by planting your Custard Apple at the same height in its new soil as it was in the pot. Burying it deeper can cause a ring of bark around the bottom of the trunk to set off rot. It is also recommended that you keep mulch away from the trunk.