The pawpaw tree (Asimina triloba), is a small deciduous tree native to the eastern United States and southern Ontario, Canada producing a large, yellowish-green fruit. Its range extends from southern Ontario and the Great Lakes region down to Florida and westward into Texas, Nebraska, and Kansas. It's commonly found in the understory of forests, particularly in moist areas like bottomlands and along streams. The pawpaw was first documented by Europeans in 1541 when Spanish conquistador Hernando de Soto encountered Native Americans cultivating and consuming it in the Mississippi Valley.
Asimina triloba is still little known in our country. It belongs to the Annonaceae family. You can sometimes find its closest relatives in fruit markets. However, these are the fruits of tropical or subtropical trees that are not suitable for growing in Central European climate conditions. Although the taste of asimina also resembles tropical fruits, it is the only frost-resistant representative of the subtropical to tropical group of fruit trees that is grown for its fruits.
Despite its very short shelf life, vulnerability to bruising, and inability to fully ripen if harvested early, pawpaw has developed a specialty market appeal in some regions of its native range. There are more than 50 selections in the USA, but only about 15 to 20 varieties are used commercially. Commercial plantations of pawpaw are limited, primarily consisting of small private orchards less than 1 hectare in size. The primary barrier to the success of pawpaw as a commercial fruit outside of its native range are the fruit's short shelf life and difficulty shipping. Pawpaws ripen quickly and have a limited time before they become overripe and lose their quality.
Pawpaw tree
The pawpaw is an exceptional tree. This is due to its unusually large leaves, its characteristic growth habit, and its beautiful autumn coloring. It usually grows tree-like and can sometimes reach up to 8 m in height when fully grown. In our latitudes, however, its growth will stop at about 4 to 5 m. Forms upright, broad pyramidal canopy. Sprouting occurs relatively late, only then do the 12 to 25 cm large, highly decorative leaves develop. They are arranged alternately and give the plants a "tropical" appearance.
Flowering and pollination
The flowers open before the leaves emerge, which only occurs very late. Depending on the variety, latitude, and altitude, the flowering period is about six weeks. In our latitudes, this occurs around the end of April/beginning of May. Now the thick, swollen, rounded flower buds, which had already formed in the previous autumn, open. They are reddish to chestnut brown, bell-shaped, about 3 to 5 cm in size, and sit in the leaf axils of previous year's shoots. Their structure is very simple, consisting of only three sepals and two rows of three petals each. Interestingly, however, each individual flower has several ovaries. This also explains why a single flower develops not just one, but several fruits (clusters). Because the flowers are self-sterile, several varieties must be planted to ensure good fruit set. The female parts of the flower (stigmas) are already receptive to pollen when the stamens are not yet fully developed. By the time the stamens release their pollen, the stigmas have already withered. Due to the specific smell of the flowers, pawpaw is not attractive to bees. Pollination in our conditions is provided by the housefly, the goldenrod beetle (Cetonia aurata), the beech beetle (Cerambyx scopolii), the alpine beetle (Rosalia alpina) and other species of beetles.
Fruits, ripening and harvest
The fruits are grouped in clusters of 3 to 9 individual fruits. Selected varieties and cultivars can grow up to 15 cm in size. The individual fruits weigh between 60 and 240 g, but can reach a maximum weight of up to 470 g. At around 1.3 to 3.0 cm, they have relatively large seeds that are dark brown to black in color. Fortunately, the fruit varieties usually contain only 8 to 10 bean-sized seeds in 2 rows. The flesh of ripe pawpaws is soft and tender, enclosed in a thin greenish to greenish-yellow skin. The consistency of the creamy-white to yellowish flesh is similar to a banana or a ripe avocado. Ripe fruits have a pleasant aroma, similar to mango or banana.
Pawpaw fruits ripen over a period of about six weeks from late August to mid-October. The fruits ripen when the color of the skin turns from fresh green to a light yellow, and sometimes, it can have flecks on the skin like a banana. To check if it’s ripe, the fruit should feel soft to the touch. You can squeeze it like you would a peach. A ripe pawpaw should also give off a sweet, exotic fragrance. Due to the long ripening period, three to four pickings are required. Grafted trees can fruit in 3-4 years after planting.
How to eat and process pawpaw fruit
Pawpaw fruits are sweet, with a custard-like texture, and a taste reminiscent of a tropical fruit cocktail of banana, mango, pineapple and vanilla. Most enthusiasts agree that the best way to enjoy pawpaw is to eat the fresh fruit straight from the tree when it is perfectly ripe. But there are also a number of ways to use them in the kitchen and extend the enjoyment of their tropical flavor after the harvest is over. The fruits are also good for cooking, baking and freezing. You can use the soft, fleshy insides in pies, cookies, ice cream, cakes and frosting. Ripe pawpaw fruits can be peeled, the seeds removed and the flesh can be pureed and frozen for later use. However, the bark, leaves, skin, and seeds contain the potent neurotoxin anonacin! Fresh fruits of the pawpaw are commonly eaten raw without the skin. Before you eat it, a pawpaw needs to be fully ripe. However, they can be kept only 2–3 days at room temperature, or about a week if refrigerated.
Location, planting and care
The pawpaw prefers a humid continental climate with moderately moist, nutrient-rich, and slightly acidic soils. Supplemental irrigation (drip irrigation) is recommended if pawpaws are to be used commercially. Since they do not tolerate waterlogging, permeable soil is important. Areas with favorable climatic conditions (such as wine-growing climates) are most suitable, so that the fruits ripen in time before the first frosts. Nevertheless, the pawpaw requires a minimum of 400 hours (about 16 to 20 days) of winter cold and at least 160 frost-free days. Due to their deep winter dormancy, the plants are very frost-hardy and can tolerate temperatures as low as -25°C. However, they can also cope with temperatures as high as +35°C. However, they are sensitive to extremely dry air, dry winds, and cool, humid summers.
An area of approximately 4 x 2 m or 4 x 3 m should be available for each tree. The side shoots grow about 15 to 30 cm annually. Apart from supplemental watering, no further maintenance is required. Pruning is generally unnecessary and is limited to removing injured or frozen parts of the plant. Competing shoots should be removed from spindle trees and steeper branches should be pruned. To keep the trees low, the crown can be thinned out; light pruning is also recommended for older plants. Pawpaws develop a taproot and are very sensitive to damage.
Nutritional Value
Pawpaw fruits have a very high nutritional value, with 80 kcal per 100 g of pulp. In terms of nutrients, they are similar to bananas: They contain 1.2% protein, 1.2% fat (with peel), 18.8% carbohydrates, and 18.3 mg/100 g vitamin C. Furthermore, their high mineral and amino acid content is also noteworthy, as these are much higher than those of apples, oranges, or bananas.
