growing pawpaws

 

Pawpaws can help you to get an additional income and to diversify the crops on your shamba.

It is important to know some general characteristics and requirements of pawpaws. In natural forestry systems, the pawpaw grows in open spaces where giant trees have been felled. It is capable of dominating the new growth during a few years. It has high light demands and disappears when the place becomes overgrown and shady as new trees grow higher.


Fertile, light soils rich in organic matter are important. Pawpaws have a flat root system; they do not require a very deep soil. But because pawpaws are not tolerant of stagnant water, the soil must be well drained. Drenching that lasts longer than 48 hours may cause the death of the plants. On the other hand, if dry periods are longer than 2 months, irrigation is necessary. But a drier period at the time of ripening is beneficial for fruit quality.


Pawpaw does not like strong wind. It should be grown in sheltered places, but in full sunshine. It may need staking and windbreaks for proper growth and fruit production. Wind breaks should be spaced at distances of about 10 to 20 times their height. For example, a tree strip that is 4 metres high can protect a strip of land that is 40 to 80 metres wide. Grow wind breaks such as silver oak (Grevillea robusta), leucaena, gliricidia, but also mango or avocado. Continuous cropping in the same field may result in poor growth and cause disease problem to pawpaw trees. After a 3-5 year period of use, the area cultivated with pawpaw should be used otherwise for some years. A second cycle with pawpaw can then be initiated. Large areas of sole pawpaw are not recommended. Pawpaw can be combined very well with cocoa and bananas for example, or be planted together with slower growing trees like mango and citrus. Short term crops such as corn or vegetables may also be considered.


The pawpaw plant has male, female, hermaphrodite (bisexual flower) and some other complex forms. Typically, the fruits from female plants have a short shape, while fruits from hermaphroditic plants are longer.


Seeds
You will need 20 to 30g of seeds per acre, if two thirds of the seeds germinate and most of the seedlings are planted successfully. Seeds are collected from the ripened fruit and spread out on mats or wooden planks to dry in the shade. They should be sown within one week. In order to harvest own seeds of a certain variety, it is essential to remove any unidentified male plants in the proximity of the plantation. Otherwise they will fertilize the flowers of your female plants, and the seeds of these fruits will bring forth cross-variety trees (and fruits) with unknown properties.


Purchased seeds: If you want to be sure to have trees of the desired variety, it is best to buy seeds. They must be from a dependable source and of good quality. They should be sown as soon as possible.


Sowing and germination The seeds are sown 1-2 cm deep. The optimum temperature for germination is 21-27° C. It takes 1 to 4 weeks from sowing to germination depending on the temperature. Pawpaw can be sown directly or at tree nurseries. Prepare the nursery about 2 months before the actual planting time. This is the period the seedlings require to be ready for transplanting.


Direct seeding: Before you sow them directly, work a mixture of ash, composted poultry dung or compost into the soil. This helps the trees to establish quickly and to dominate the system within a few weeks. Sow 3 to 5 seeds per hole to compensate for poor germination, virus infection, insect damage and removal of male plants at the time of flowering.


Pot or bag sowing: The substrate consisting of tilled clay and sand soil mixed with compost should be placed into the pots or Polyethylene bags around 2 weeks before sowing. Sow 2-3 seeds per pot.


Nursery beds: Sow the seeds in raised beds. The soil should be fine and mixed with generous amounts of decayed farmyard manure or compost. Sow the seeds 1-2 cm deep and 2-3 cm apart. Rows are spaced at 15 cm. Sprinkle the seed beds daily with a watering can except on rainy days. Avoid water logging as this may lead to fungal diseases and “damping off” of the seedlings.
When the seedlings are 2 to 3 weeks old, they may be sprayed with a fungicide solution. Dissolve 1g of copper oxychloride in 1 litre of water.


Transplanting
Transplant the seedlings when they are about 20 cm tall, or up to 40 cm if they are grown in larger containers. They can be planted year round if irrigation is available. If the soil is not well drained, a 40-60 cm high bed is required.
Drill planting holes about 45cm in diameter and 30cm in depth. Mix the soil with plenty of well rotted compost for planting. The plants and rows should have a distance between 2m and 3m in the end, but this should be coordinated with the requirements of any additional crops. Usually, you will want to uproot virus-infected plants and excess male and female plants later, so the distance between plants at transplanting may be about 1m.


The seedlings should be well watered one day before transplanting. Transplant them on a cloudy day or in the late afternoon to minimize transplanting shock. The roots of pawpaws consist of a tap root and hair roots in the upper parts. Make sure not to damage the hair roots during replanting. Take care not to plant too deep; otherwise collar-rot disease may affect the buried part of the stem. Then water immediately after planting.



Thinning out
When the first flower buds appear after about 3 to 5 months, the seedling’s sex can be determined and plants should be thinned out. For pollination of female plants, 10-20% hermaphrodite plants or 1 male per 25 females are required. If hermaphrodite varieties are planted, only virus-infected plants and excess plants are eliminated.


Nutrition
Pawpaws prefer very fertile soils with high organic matter content. This should already be considered when choosing a site. Pawpaw is a heavy feeder and has a continuous demand for nutrients. Increased nutrient uptake is observed after flowering. For fertilization, use mature and composted animal manure at a rate of 2 to 5 kg per plant and per year, plant teas and compost. A sufficiently thick layer of mulch is very beneficial and especially important in dry seasons.


Weed control
Mulch the bed with rice or sugarcane straws or any other organic material like hedge cuttings within a few days after transplanting. This controls weeds, soil erosion and water loss, and adds organic matter and nutrients. Weeds should be frequently and lightly removed at a young stage. Be careful when weeding as the plant has shallow roots. Cut down mature weeds to use for mulching, and remove grasses with their roots intact.


Tips for the maintenance
• Diseased and dead plants need to be removed and composted.
• Remove the side shoots of the stem.
• Cut back all bushes and young trees that loom over the pawpaw after 6-8 months.
• Remove fruits which are poorly pollinated, malformed or pest-infected.
• Support the plant with stakes when bearing heavy fruits and during stormy seasons.


Pawpaw may live as long as 15 to 20 years, but it is profitable only for about 3 years. As the tree grows taller and older, the fruits become sparser, and they are borne at greater height on the trunk. The growth slows down after 3 years, and fruits and leaves diminish in size. Remove the plant at this stage, as it will be uneconomical to maintain it any longer. A good strategy is to plant other trees on papaya plots and to plant new papayas where free plots appear on the farm, or where old trees (other than pawpaw) were removed.