Tropical Gardening: Are GMOs good or bad?

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The answer to the questions posed in the above headline depends on how the technology is used.

The answer to the questions posed in the above headline depends on how the technology is used.

The issue of genetically modified plants or animals is very complex as is any new technology. Actually, the GMO issue is just a new twist on what we humans have done for centuries.

By hybridizing, creating and selecting advantageous mutations, we created thousands of varieties of orchids, citrus, bananas and many other plants. Because it is a great leap of this technology, we tend to be wary and that is good.

For example, electrical power can be used in a way as to make our lives better or it can kill. Even the discovery of nuclear power and its use or misuse can be argued. Probably the first human to create a fire was considered a witch.

That is not to say we should rush head on into new technologies without recognizing they might have serious downsides. In the other extreme, do we want to simply reject advances in science because we might create a Frankenstein monster?

A healthy and respectful dialogue is important as we explore any new technology. To totally ban all GMOs to be grown or sold would be throwing out the baby with the bath water.

Farmers need to have the opportunity to choose if they want to grow their crops organically or with safe use of pesticides or GMO-free as long as consumers know what we are buying. At the very least, foods should be labeled GMO or not GMO so we have a choice.

Let’s take a look at just one example.

Papayas have been valuable food and medicinal plants throughout the tropical world. In the early 1950s, a devastating disease called papaya ring spot mosaic wiped out the papaya industry in Florida and many areas of tropical America, including the Caribbean. Later, the disease hit Hawaii.

Luckily, some scientists were working on the problem and developed a genetically modified papaya that is resistant to the mosaic virus. Today, we can grow papaya plants in regions previously infested with the virus thanks to those efforts.

There are many examples of new technologies being misused.

Taken to the extreme, genetically modified organisms could be used to create neon cats that glow in the dark. Or, we can work with the technology to give humans protection from such diseases as Ebola, dengue, Zika, chikungunya and other viruses that are causing havoc in many parts of the world. Several experimental vaccines are now being tested because of this technology.

Can you imagine using the technology to help our endemic honeycreepers resist the ravages of disease, thus allowing them to again populate our islands in abundance?

Since folks will be discussing the pros and cons of GMOs for years to come, let’s just focus on growing healthy, virus-free papayas in your home garden.

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Papaya plants are a natural for almost any garden. They are prolific and nutritious as well. Probably no other plant supplies the home gardener so much for so little effort.

This tropical American, herbaceous, tree-like plant will grow and produce fruit all year with a minimum of care.

Green, unripe papayas are high in papain, which helps digestion. The leaves also are high in papain and can be used in cooking. Ripe fruits are high in calcium and vitamins A and C.

Your garden can supply a generous amount of these delicious fruits. By following modern methods, you also can grow many other tropical fruits. But one of the best is papaya.

Start out with good plants, proper attention to fertilizer and moisture needs, and keep insects under control. You’ll harvest some very good fruit that will repay you for your trouble.

There are several varieties, from the big watermelon fruit to the small solo types. Most folks prefer the bisexual, or solo, strain of papaya. This type produces a high percentage of top quality fruit.

Seeds from the large watermelon types produce male, female and bisexual trees. Most of the male trees must be eliminated as soon as they are detected. They are identified by means of their bloom stems. These are sometimes up to more than a foot in length and have many flowers.

Female blooms are produced close to the stem but have no pollen bearing stamen. Bisexual flowers have ovary and stamen, thus can self-pollinate.

Occasionally, garden shops and nurseries offer solo papaya plants for sale, and the gardener who needs a few plants will do well to buy his plants rather than attempt to grow them from seed.

For larger numbers of plants, you can grow seed from selected fruit. Seed order forms are available from the University of Hawaii Cooperative Extension Service.

The papaya is a relatively short-lived herbaceous plant, reaching a height of 15 feet or taller in five years. A top quality plant should produce more than 150 pounds in a two-year period. Commercial growers often harvest up to 300 pounds from a plant during a two-year period. After that, the plant becomes so tall it is difficult to pick fruit. Production also drops rapidly.

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Here are some tips for successful papaya production.

Select seeds from a fruit you like or purchase University of Hawaii seed. Plant three of four seeds in individual containers, preferably those from which the plants and soil can be removed without injury to roots. Paper potting cups are OK for planting, as long as they have good drainage.

When seeds begin to sprout, fertilize with a soluble fertilizer once a week, mixing according to the manufacturer’s directions. It takes six to eight weeks to raise plants large enough to set out in permanent locations.

Set plants in permanent sunny locations at least 8 feet apart. The area should receive as much sun as possible. Put about three plants to a hill, 1 foot apart. Keep them there until you determine the sex, then remove the males and weak females.

If the soil in which you are to set young papaya plants is poor, prepare it two weeks ahead of planting by spreading complete garden fertilizer such as 8-8-8, 16-16-16, or 10-30-10 over a 4-square-foot area about the size of each hill and dig the fertilizer into the soil. Wet it down so the fertilizer will dissolve and mix well with the soil.

Soil also must be free of nematodes that can cause root knot damage in papaya.

Fertilize newly set out plants once a week with soluble fertilizer for the first month. Then, begin fertilizing with a regular dry garden fertilizer, applying once a month.

The papaya requires large amounts of fertilizer for best production. Spread the fertilizer out over an area roughly covered by the leaves.

A papaya plant won’t thrive in soil that is very dry or poorly drained. Young plants must be kept well-watered until they are established, then watered every four or five days during the dry season. Mulching will help conserve moisture. In wetter areas of the island, irrigation will only be necessary during drought periods.

Pests can give papaya growers trouble. The worst pests are aphids, mites and fruit flies.

There has been no insecticide that offers satisfactory control of the fruit fly in dooryard plantings. Harvesting fruit before they become over-ripe will help keep damage to a minimum.

Sanitation also is important. Do not leave fruit to rot in the garden, thus allowing fruit flies and other unwanted pests to proliferate.

Mites, almost microscopic spider-like creatures, sometimes cause visual damage. This does not usually affect the taste of the fruit.

Nematodes, microscopic worms that feed on papaya roots, also are a problem. Good fertilization practices and mulching will minimize nematode damage.

With little effort your papaya plants should reward you with abundance.

For other home garden questions, call the University of Hawaii College of Tropical Agriculture and Human Resources Master Gardener helpline in Hilo and Kona.