History and Basic Information for PawPaw Trees and Fruit
Asimina Triloba, or Pawpaws are a great tree for yards and gardens. As an ornamental, it has an attractive tropical look with long, full, oval leaves and a small pyramidal stature suitable to smaller yards. Although there is some maintenance in the first two years, it is very low maintenance afterwords. It supplies delicious, nutritious fruit, which will set on 5-6 years on a seedling or 3 years on a grafted tree after planting.
Certain strains of Asimina Triloba pawpaw has been adapted to the southern UK climate and soil conditions. It is hardy (to -30 Celsius when dormant), and needs at least 300 hours in annual chilling requirements (depending on the cultivar). This is a low chill requirement compared to other tree fruit species (apples 800 to 1,700 hours), and once met, the trees will begin to flower early in the spring. A long, warm season is required to mature fruit (2,600 degree days; ~160 frost-free days). From 30 to 35 inches of rainfall is needed annually, with the majority falling in the spring and summer. Contrary to popular belief, pawpaw performs best in full-sun exposure. However, sunlight protection is needed in the first two years in the field, as young tree shoots are sensitive to sunlight. This accomplished by using commercially available tree shelters or making a cover to block full sun in the first two years. Grafted trees do not have this issue as the scion wood previously built up protection.
Pawpaws should be planted at a site that would be appropriate for production of tree fruit such as apples, peaches or plums. A sloping orchard with good air drainage will reduce the risk of damage from spring frosts. Soil should be augments with loam, peat moss and leaf mould if possible.The location for planting should have deep (3 feet is optimal), well drained, fertile soil with a pH of 5.5 to 7.0. Irrigation and weed control is also important for tree establishment. We recommend a planting distance of 8’ between trees.
Wild trees seldom grow higher than 25 feet, some grafted trees only reach 12ft and develop a nice pyramidal shape in full sun. For maturing trees, we recommend only corrective pruning. Remove limbs to about 2.5 feet from the ground. Remove limbs that cross and any diseased wood. Prune in late winter or early spring before bud break.
Historically, Asimina Triloba or Pawpaws have been a difficult tree species to propagate. What appear to be small pawpaw trees in a wild patch are often be rootsuckers that have poorly developed root systems and often do not survive transplanting. Pawpaw seeds are desiccation sensitive and require proper stratification to germinate effectively. Pawpaws have very long tap roots that are easily damaged. As such, it is best to buy a tree from a clonal propagation source of select cultivars. When purchasing trees, consider the advantages of grafted trees over seedlings. Seedlings undergo a period of juvenility and require a period of 5-8 years before producing flowers. Seedling fruit quality can also be poor. Grafted cultivars can produce flowers 2-3 years after planting. Grafted trees also have a known fruit quality, but take about 4-6 years to reach full fruit production. The first two years of he pawpaws life are the most important.
Pawpaws have few pests and can be grown organically. When there is poor fruit set on a tree, it can often be from a lack of sunlight, or poor soil conditions. If genetically different trees are not nearby for pollination, fruit set can also be low (with the exception of Prima or Sunflower). Therefore, it is critical to have genetically varied trees if you seek to grow your own fruit. Finally, remember, flies and beetles, not bees are the major pollinators of pawpaw, and a lack of pollinators can also lead to poor fruit set. This cam be overcome with simple hand pollination.
Nutritional Value of PawPaws
The pawpaw is a unique/unusual fruit crop with high nutritional value and potential for both fresh and processed uses. As a food source, pawpaw exceeds apple, peach, and grapes in vitamin, mineral, amino acid, and food energy values.
Major Nutrient Makeup: Pawpaw fruits vary in size, usually ranging from 5 ounces to a pound each. A 100-gram serving, or about 3.5 ounces, of pawpaw fruit provides 80 calories, 1.2 grams of each protein and fat and 18.8 grams of carbohydrates, including 2.6 grams of fiber, or 10 percent of the daily value. Fiber helps fill you up on fewer calories and may lower your risk for heart disease, constipation, and Type 2 diabetes.
Vital Vitamin Content: A serving of pawpaw fruit contains about 31 percent of the daily value for vitamin C, as well as small amounts of vitamin A, thiamine, niacin and riboflavin. Vitamin C acts as an antioxidant, helping to keep your cells from becoming damaged by harmful substances called free radicals. You also need vitamin C for forming collagen and healing wounds.
Manganese, Magnesium and Other Minerals: You’ll get a significant amount of many of the essential minerals each time you eat a pawpaw fruit. For every 100 grams, pawpaw fruit provides approximately 10 percent of the daily value for potassium, 39 percent of the daily value for iron, 130 percent of the daily value for manganese, 11 percent of the daily value for magnesium and 25 percent of the daily value for copper. Potassium helps counteract the blood pressure increases caused by sodium, iron helps form red blood cells and manganese helps form bones and process cholesterol in the body. You need magnesium for proper muscle and nerve function and copper for a healthy immune system.
American and European History of Pawpaws
The pawpaw is a true native to North America and has a long history in the United States, and is now available in the United Kingdom. The fruit of the pawpaw was a key component of Native American Indian diets; indeed, the Shawnee Indians even had a “pawpaw month” dedicated to the fruit in their calendar
The Spanish discovered the pawpaw in 1541. The first European mention of the pawpaw dates to Hernanado de Soto’s 1540 Mississippi expedition, where a fellow traveller noted the fruit being cultivated by American Indians. From journal entries it is reported that it was the pawpaw that fed the Lewis & Clark expedition on their return trip in the fall of 1810. The Pawpaw fruits saved the expedition from starvation and death when in western Missouri their food rations ran low and no food was to be found. Two U.S. presidents favoured Pawpaws: George Washington reportedly enjoyed them as his favourite dessert, and Thomas Jefferson was known to have grown Pawpaws at Monticello where he too enjoyed the delightful fruit.
Pawpaws did not become popular in Europe until the end of the 20th century. During the Great Depression, the pawpaw was also frequently consumed as a substitute for other fruits and were thus called the “poor man’s bananas”. Though the pawpaw continued to be an important fruit in the North American diet, interest waned after World War II with the introduction of other fruits. Nowadays, most Pawpaws are very difficult to find outside of a few local farm markets.
Uses of PawPaw Bananas
The pawpaw is a unique/unusual fruit crop with high nutritional value and potential for both fresh and processed market uses. As a food source, pawpaw exceeds apple, peach, and grapes in vitamin, mineral, amino acid, and food energy values.
The current and primary market for fruit in the USA and Canada is as a fresh product in farmers markets and other direct sales outlets. Though large-scale commercial processing markets do not yet exist, the fruit’s intense flavour and aroma have significant potential in blended fruit drinks, baby food, ice cream, and as a substitute for banana in various baking recipes. In Kentucky and Ohio, various entrepreneurs are utilizing Pawpaws in alcoholic beverages such as beer and as a local cuisine item for restaurants and in frozen custard and ice cream products.
There are valuable natural compounds in the plant, which have both anti-carcinogenic and pesticide properties. Aromatic compounds in the fruit have potential for use in cosmetics and home products. Research has shown that Pawpaws have a diversity of natural compounds in fruit, leaves, bark, and twigs. One class of compounds known as annoaceous acetogenins occurs in the Asimina Triloba leaves and bark and has reported anti-tumor properties. The term 'annonaceous acetogenin' derives from the plant family, 'Annonaceae', which includes the custard apple family of plants. 'Acetogenin' refers to 'being generated from acetate', and relates to the polyketide origin of these chemicals. Purdue University has patented an extraction procedure and the development of an herbal formulation is underway by a private company. An alkaloid, asimicin, is found in the seeds, leaves, and bark of pawpaw and is reported to have pesticide properties. Pawpaws are resistant to insect and disease pressure. This may be due to asimicin and other natural defence compounds.
Most recently, Pawpaws have become a hit with distillers and craft brewers. Some of the newest micro-brews in the USA are now are being made with Pawpaw extracts. Pawpaw also make sweet, flavourful beers, wines and an exquisitely tasting schnapps.