This article was originally produced  on  May 19, 1999  as a bi-monthly news column for the Vero Beach Press Journal

Date of release:  May 23, 1999

Daniel F. Culbert, County Extension Agent

BALSAM APPLE: WEED OR VEGETABLE?

"What is this weedy vine - and how can I get rid of it?" Last week our office was asked to identify a weed sample brought to us by a home owner. The Balsam Apple is commonly found in Indian River yards and roadside areas, and is recognized as a plant that is a nusiance and could be dangerous. Information for today’s column comes from our University of Florida’s Extension Specialists David W. Hall and Vernon V. Vandiver.

This plant is found in our hammocks, disturbed sites, turfs and ornamental landscapes, and citrus groves from Florida to Texas. It is native to tropical Africa and South east Asia, and was introduced into Europe in 1710. Balsam Apple has escaped cultivation, and is considered by most local residents to be a problematic weed in our Florida Yards. It can be found growing year round in the most tropical areas of the world, and may be grown as an annual in areas subject to freezes.

A WILD CUCUMBER

Balsam-apple (Momordica charantia L. ) is a member of the Cucumber Family. The genus name comes from the Latin word Mordio, to bite, and refers to the bitten appearance of the uneven seeds. The species name, charantia, refers to the pointed fruit.

Confusion is encountered in references between the species in this group of plants. M. balsamina is native to east India, and is known as Balsam Pear, Bitter Cucumber, La-Kwa, or Bitter Melon. This plant is an article of food in the Orient, but is mainly grown as a curiosity in the U.S. and is described as being a more elegant plant than the Balsam Apple. It is more popularly cultivated as a climbing annual plant cultivated in gardens for the sake of its ornamental fruit which is larger than that of our local weed . Momordica mixta is another species with fruit shaped like a bull's heart, with bright red fruit.

The plant rapidly grows from seed and produces high-climbing vines. The stem is ridged with slightly fuzzy stems. The dark green deeply lobed leaves alternate on the stem, and produce tendrils that wrap around what ever it can to support the vine on fences or other plants. The leaf blades are hairy to smooth, deeply palmately five- to seven-lobed and up to three inches wide. The lobes of the blades can be rounded or pointed. The first leaves of a seedling are unlobed with broad teeth along the margins and it will have a heart-shaped base.

It doesn’t take long for the vines to produce yellow blossoms which have five petals and are an inch in diameter. As with most cucumber plants, the flowers are dioecious: they will have separate flowers with either male or female parts. The flowers usually occur singly on stalks bearing a modified leaf near the middle. The sepals (outermost flower parts) are oval and almost a quarter inch long. The yellow petals are rounded or indented at the tips and up to one-half inch long. Male flowers produce only pollen, while the female flowers produce handsome, oblong, lumpy fruits. Immature fruit are light green to greenish-white, waxy skin that are three inches long and tapered at both ends. The fruit is broadly egg shaped, beaked, bumpy, ribbed, three to four inches long and golden yellow to bright orange. At maturity the fruit breaks, bursting open along three seams. The orange pulp contains bright red arils which enclose the seeds. The seeds are elliptic, flat, and one quarter inch long. The "Apple" in Balsam Apple refers to the bright red pulp surrounding the seeds, which are seen when the mature orange rind ruptures and exposes the seeds. The ripe fruits and seeds are toxic.

TAMING UNWANTED VINES

Most local residents that discover Balsam apple vines invading their fences and crawling though the landscape want to know how to get rid of this invader. There are no magic herbicides that can be used to selectively kill this plant without damaging other landscape plants.

The key to managing this weed is to keep ahead of it. If you regularly observe your landscape, hand removal of small seedlings before they take over is the best course of action. If you observe a seedling that volunteers from the seed left behind from the Balsam Apple fruit, you will then know what a young plant looks like, and train your eye to pick it out from your landscape plant beds while it is small.

For those situations where Balsam Apple has got out of hand, the use of our old standby herbicide glyphosate can help to kill the vine. You know this chemical as Roundup™, a non-selective, systemic weed killer that kills what ever it touches. Reading the label and following all label directions is not only a good idea when using this product, it is FEDERAL LAW!

The weed killer will kill the vine and the roots, but it will not kill mature seed that have already been produced. To prevent further episodes of this vine crawling around your Florida Yard, careful removal of all the fruit from dead vines before they drop their seed will be needed. And since it is unlikely that you will be able to get them all, follow up management is needed . By carefully looking for new seedlings and promptly pulling them up before they grow flowers, you will reduce the chances that Balsam Apple will be a problem.

AN EXOTIC ORNAMENTAL VEGETABLE ?

While most will consider this plant to be a weed, Balsam Apple has been used an ornamental vine, and some persons are known to growing the plant as an exotic vegetable. Plants should be set two feet apart and provided with support such as a trellis, arbor, fence, or wires. A lot of water is needed when the plants are growing actively - if the soil becomes dry, the fruits will drop.

In the landscape the larger fruited Bitter melon has been widely planted as an ornamental in much of the world. Its lobed, deeply veined leaves and small, yellow flowers look striking cascading over a retaining wall or large oak barrel. Our local balsam apple could be used in a similar fashion, but care should be given to prevent it from escaping and becoming a weed.

For those tempted to use Balsam Apple as a vegetable, a word of caution: do not eat fruit with ripe seeds; they are reputed to be a purgative. The large fruited Balsam Pear used in cultivation is harvested immature to reduce bitter tastes due to the presence of quinine. Like most squash, older fruits can be terribly bitter and chewy. The flesh is soft when cooked, reported to be somewhat like that of summer squash. These references are describing the use of M. balsamina, a larger fruited species, not our local escaped weed. I would not recommend using our local Balsam Apple (M. charantia) as a food source because of the potential danger of poisoning.

There are some medicinal action and uses reported by some references, but because the Constituents have not been examined through qualitative research, that can not be recommended by the University. One reference notes that a liniment is made by adding the pulped fruit (without the seeds) to almond oil, but it also suggests caution is required in administering large doses which could result in death.