Bitter Melon (Momordica charantia).
Bitter Gourd is also known as Bitter Melon and Balsam Pear, and is an herbaceous, annual vine. It is up to 3 to 4 m long, and is a weed of the tropics and sub-tropics. Bitter Gourd is grown for its edible fruit, which is among the most bitter of all fruits due to its high levels of momordicin.
Momordicin is used to treat Parkinson’s disease and strokes. The mature fruit and seeds are toxic and should not be eaten.
Bitter Melon lives about three months, and it has a bad smell if you crush the leaves. It has a taproot system with a spreading root network.
After you read this, you will be able to:
- Identify Bitter Gourd, Balsam Pear or Bitter Melon.
- Know where Bitter Melon grows.
- Know the best options to control Balsam Pear.
Bitter Gourd is found in Northern Queensland, and also NSW and the NT. It competes with crops and native plants, and also interferes with the growth of vegetables, orchard and plantation crops. As it climbs over these, it aggressively competes for light, nutrients and water.
There are several reasons why this weed is so invasive:
- It tolerates 500 to 4000 mm of rain a year.
- Bitter Gourd grows in a wide soil pH range (4.3 to 8.7).
- It grows rapidly.
- There are only 30 days between when it germinates and when it flowers.
- Bitter Melon has tenacious tendrils that coil and act like a spring to raise the stem.
In Australia, Bitter Gourd is not a prohibited or restricted invasive plant. By law, everyone has a general biosecurity obligation to take reasonable and practical measures to minimise the risks associated with invasive plants under their control.
The distribution map for Bitter Gourd is from The Atlas of Living Australia.
How to Identify Bitter Gourd.
Category: This is Broadleaf (Dicot) weed.
Photosynthetic Pathway: Bitter Melon is a C4 Weed.
Flower: Bitter Gourd has yellow flowers with five petals, that are about 2 cm across. These flowers open early in the morning before daylight with the flower buds being fully open and functional at dawn (anthesis).
Height: Vine.
Leaf length: Each deeply lobed leaf of Bitter Gourd is 4 to 10 cm long, and has a round outline.
Leaf width: The soft, mid-green leaves are on stalks. They are deeply divide into 5 to 7 shallow scalloped lobes, that are up to 15 cm across.
Reproduction: Bitter Gourd spreads by seeds and alo by underground stems. The ripe fruit is orange to yellow, 10 to 20 cm long, ridged and has a cover of blunt warts. Once the fruit matures, it bursts along its length and curls back to expose the edible scarlet flesh around its many black seeds.
If you keep the seeds in dry storage, they remain viable for up to 24 months.
Comments: Bitter Gourd does not tolerate frost.
Habitat: You often find Bitter Gourd in roadsides, gardens, fencelines and around houses and farm buildings.
For more information on weeds check out our weed ID Chart.
How to Control Bitter Gourd.
You can control Bitter Gourd or Bitter Melon by cultural and chemical means, but successful management of this weed is best if you adopt an integrated approach.
Cultural control:
- Hand pull individual plants and small popumations, but you must make sure that you remove all the roots and stem fragments. You should either bag these off and take them offsite or hang them up off the ground to prevent any re-growth.
- You can also cut plants down to the soil. This is very labour-intensive as you need to repeat this several times to achieve control. This is because the roots regrow from the taproot.
Chemical Control of Bitter Gourd.
The key to the control of Balsam Pear is to reduce the seed bank, and then keep it at a low level. In Australia, Flumioxazin is currently the only registered herbicide for the control of Balsam Pear in commercial and industrial areas.
APVMA Permit (PER11463) is for this weed, but you must read and understand the conditions of the permit. Products on this permit include:
- 2,4-D and
- Fluroxypyr. Work in sugar cane shows that a mixture of fluroxypyr at 260 g a.i /Ha and Dicamba is an effective control method that achieves an 83% plant mortality.
Overseas work has shown that effective control occurs after three rounds of spraying with a post emergent herbicide.
- In Brazil they use the following herbicides to control this weed: Glyphosate, Dicamba and Triclopyr.
Non Selective Control of Bitter Gourd.
The non-selective Glyphosate, controls this weed although there are repoprts of herbicide resistance overseas. If you use Glyphosate and water quality is an issue then use ProForce Manta Ray.
Other Non selective options to look at are Numchuk Quad and Cortex Duo. Both of these are great knockdowns but also have a long term residual of up to 12 and 3 months respectively after you use them. These are ideal for along fencelines or around buildings.
