Papayas not native to isles, but thrive in sunny weather

Question: I’ve heard the term "Hawaiian papaya." Is papaya a native plant?

Answer: No, papaya was introduced into Hawaii from Barbados in 1911. The introduced species was later named "Solo" in 1919 and is known to the trade as "Hawaiian" papaya because it is primarily grown here.

Q: What conditions does papaya grow best in?

A: Papaya is considered to be a short-lived perennial, although some trees have been known to live as long as 20 years. While papaya will grow in a variety of soils, it requires excellent drainage and prefers a soil pH of 5.5 to 6.5. To improve drainage, it can be planted on slopes or in raised beds. Papaya grows best in full sun in warm areas below 500 feet elevation. The plants should be protected from strong winds and can suffer from salt damage if planted too close to the shore.

While papayas thrive in warm areas, they do require sufficient water. In areas of low rainfall, they may need supplemental watering. Insufficient water results in low fruit production, leaf drop and eventually death. In addition, it can cause hermaphroditic plants to shift toward maleness.

Only fertilize after a soil test to determine what the plant’s needs are. Your local University of Hawaii Cooperative Extension office can help you submit a soil sample to the UH Agricultural Diagnostic Service Center (www.ctahr.hawaii.edu/oc/freepubs/pdf/AS-4.pdf).

Q: My papaya tree makes flowers but they never turn into fruit. What’s the problem?

A: Papayas can be either dioecious or hermaphroditic. Plants that are dioecious have male and female flowers on different individual plants. The female flowers have conical buds, free petals, a large ovary and no stamen. Male flowers have a smaller, slender, spoon-shaped bud with petals fused at the base.

Female plants require cross-pollination to produce fruit, while male plants will not produce fruit at all. You may have a female tree that is not being pollinated, or a male tree.

Hermaphroditic plants have perfect flowers, which contain both male and female organs. These plants are self-pollinating. UH cultivars Kapoho, Waimanalo, Sunrise and Sunset produce only female and hermaphroditic flowers. To ensure success in fruiting, it’s best to plant more than one plant to avoid having one single female. Allow the plants to flower so you can see which they are, and then remove all but the healthiest hermaphroditic plants.

You can buy cultivars through the UH Seed Program (www.ctahr.hawaii.edu/seed/index.asp) or from your local master gardener program.

Q: What are some pests that attack papaya?

A: Pests include several types of mites, thrips, leafhoppers, fruit fly, aphids, mealybugs and whitefly. When the plant is infested with honeydew-producing pests such as aphids, mealybugs and whitefly, ants are usually present as well, and they will also need to be managed along with the plant-feeding insects to gain control of these pests.

Papaya diseases include papaya ringspot virus, anthracnose, phythophthora, powdery mildew, several fruit rots and nematodes. If you suspect a disease on your papaya, contact your local Cooperative Extension office.

For more information on papaya and other fruits, visit the College of Tropical Agriculture and Human Resources Publication and Information Central (www.ctahr.hawaii.edu/site/Info.aspx).

Lorraine Brooks is an urban horticulture extension agent and the Maui Master Gardener coordinator with the University of Hawaii’s Cooperative Extension Service, part of the College of Tropical Agriculture and Human Resources. Email her at llb@hawaii.edu.