SOURSOP (Anona Muricata L.).

GENERALITIES
Family: Annonacea
Species: Annona muricata
Origin: Central America, West Indies.
Principle Producers: Tropical America and Southeast Asia.

The fruit of the soursop (Annona muricata) is generally large, with a dark green skin, adorned with pronounced nipples, a conical shape, although this can sometimes be irregular and variable depending on the variety, it has a white pulp and an impeccable crust, the stem is cut flush. The fruit should be physiologically well developed without being too mature, with a firm texture to the touch and sufficiently ripe for subsequent maturation during storage.

The word Annona is derived from the Latin "annual harvest". It is a tree or perennial shrub that can grow between 3-12 metres high. It reaches full development between 4-8 years and its longevity, depending on the methods and practices during cultivation, can exceed 15 years.

Soursop grows well between 300 and 1200 metres above sea level. The ideal growing temperature is between 25-28 degrees Celsius, when temperatures drop below 12 degrees defoliation occurs as well as damage to branches and difficulties during the blossom phase. The soursop requires a great deal of sunlight and behaves very well in areas where rainfall distribution is between 800-1000mm per year, the relative humidity should be above 80% for a good natural pollination and consequently a good fruit production. The recommended soil for planting should have a pH between 5.5 and 6.5 and should be deep with good physical properties. In clay soils, a good system of drainage should be considered, the properties of loam soil are the most appropriate.

As is the case with almost all types of fruit, knowing the phenology of the crop is vital for the consideration of factors such as cultivation management, fertilization, pests and diseases as well as harvesting and marketing.

The soursop’s productivity is affected by insects and diseases and this crop requires a high level of phytosanitary management, as there are several agents capable of causing critical damage to the development of the tree.

Identifying these agents, understanding the symptoms, the damage they cause, the ecological conditions that favour them and the specific periods during which risk of attack is greatest are key aspects of ensuring a healthy development of the tree.

Among the most debilitating pests we encounter: the Soursop seed boring wasp (Bephratelloides maculicollis) the Green Parrot insect (Empoasca sp.) the Citrus Mealy bug (Planococcus citri); the “Pegapega” Moth (platynota sp) and the fruit boring Annona moth (Cerconota anonella sp.) And among the diseases the anthracnose fungus (Colletotrichum gloeosporioides), which is particularly aggressive.

As the tree has a tendency to ramificate, pruning is very important and is recommended during soursop cultivation, enabling greater light penetration, tighter pest control and facilitating an easier harvest. Similarly, it is necessary to make a plan for maintenance and health pruning.

Harvest: Soursop trees tend to flower and bear fruit throughout the year. As a very delicate but relatively large fruit with an extremely thin shell, it should be harvested before fully ripening using scissors or by hand.
Fruits should be clean, healthy and free from damage caused by pests, disease or abuse, and general physiological defects; no breaks in the skin; free of toxic fumigants, sunburn or other burns and without traces of anthracnose; fresh with no signs of dehydration, replete with its characteristic aroma and flavour.

Post-harvest: In order to provide superior specimens of soursop to the fresh market, a process of classification is undertaken, a judgement of quality based on criteria, the general requirements being: dark green fruits around 15 to 20 cm long and 10 to 25 cm wide; covered with soft spines turned toward the apex; a thin and leathery skin; a creamy white, meaty pulp that is juicy and slightly acidic. The weight ranges from 1 to 5 kg but examples weighing up to 25 kg can be found. Fruit should be between ½ and ¾ ripe, but fully ripe is acceptable where immediate consumption is desired. The fruit must be complete, no scratches or bruises and very clean, no smell other than their own distinguishing aroma.

Storage: Normally in Colombia the fruit is left for several days in bags, or newspaper in a warm place to ripen well and procure the best flavour before consumption. The shelf life of the fruit after cutting is 6 days.

Benefits: The soursop is one of the most desired of all tropical fruits for industrial production of juices, ice cream and sweet pulp.