| September 2003. How to control Balsam pear, Momordica charantia; that was the question asked by NARI, the National Agricultural Research Institute, Papua New Guinea. The weed is infesting a conservation areas run by NGO.
Glyphosate (Roundup) should work effectively against Mormordica sp. Follow the recommendations for acidifying your tank mixture before application. The target pH is between 5.5 – 6.0 for best results. Ammonium sulfate or plain vinegar can be used to achieve this.
It is also easy to uproot, simply by pulling! But note a combination of hand weeding and herbicides might be required. Also, if the infestations being tackled are quite large, it is important to be determined, systematic, well-timed, organised and persistent – it may take a number of years to peg the target species back, and it may never be eradicated (depends on the extent of the problem). By well-timed, spraying and hand pulling may need to be done before the annual flowering of the plant, to make sure not to spread more seeds when the plants are being cleared.
There are a number of useful websites:
The FAO website stated:
Momordica charantia – balsam pear
A vigorous, twining vine with soft, mid-green leaves, deeply divided into 5 to 7 lobes. Flowers are yellow and about 2 cm in diameter. Balsam pear is an invader of recently cleared, plateau soils in areas of high rainfall. It is generally kept under control by trampling and light grazing by cattle. In ungrazed situations balsam pear may become dominant, smothering out less aggressive species.
Balsam pear can be substantially controlled by hand or tractor slashing or by heavy, rotational grazing. It is resistant to 2,4-D but can be killed by spraying with Grazon at 0.5%.”
…. and information from Guyana: www.uog.edu.gy/faculties/faf/Agric_abstracts.htm
The Biology and Control of Momordica charantia (Band Carilla)
Momordica charantia is a problem weed to some cultivated crops in Guyana e.g. sugar cane. Its life cycle was investigated from germination to the production of matured fruits. Factors such as dormancy, mode of germination, seedling emergence and stages in developmental growth of plant after emergence were examined and recorded, with respect to germination percentage and new plant parts related to time. The weed’s response, to four chemicals (Aclonifen, Banvel, Grandstan and oxytril) was tested using a visual method to measure these responses. It was shown that dormancy does exist (55% germination) when compared with seeds treated to break dormancy (80.81% germination). A seed could remain viable for at least 6 months. The mode of emergence is active hypocotyl and this vine emerge best at the planting depth of 1-3 inches. 12-15 days is the time period for maximum emergence after planting, and six weeks later mature fruits are produced. Alconifen and Grandstan completely controlled the weed 3 weeks after application, as against Banvel and oxytril which showed little or no control.