Rhamphicarpa fistulosa

Rhamphicarpa fistulosa is a herbaceous plant belonging to the Orobanchaceae family. It is recognized as a facultative root hemiparasite, meaning that while it possesses chlorophyll and can perform photosynthesis, it relies on attaching its haustoria to the roots of a host plant to obtain water and mineral nutrients, particularly during its later growth stages.

This weed is primarily found in sub-Saharan Africa and poses a significant threat to agricultural stability. It is most notorious for infesting rice crops, including both upland and rain-fed systems. Its presence in fields can significantly diminish the quality and quantity of rice yields if left unchecked.

The biology of Rhamphicarpa fistulosa is highly adapted to parasitism. Its seeds are minute and can remain viable in the soil for several years. The germination process is strictly triggered by chemical signals (strigolactones) released by host plant roots, which ensures that the germinating seedling establishes a parasitic connection immediately.

The damage caused by this weed is severe, often resulting in heavy crop failure. By extracting nutrients and water directly from the rice roots, the weed causes the host plants to stunt, wilt, and exhibit yellowing. In heavily infested areas, farmers can experience yield losses ranging from 50% to almost total loss of the harvest.

Management strategies focus on reducing the soil seed bank and preventing attachment.

• Utilizing trap crops to induce suicide germination of seeds.
• Implementing crop rotations with non-host species.
• Hand-weeding before seed set to stop future infestations.
• Using resistant or tolerant rice varieties.
• Applying targeted herbicides at the seedling stage of the weed.