Arrowleafed monochoria

Scientific name: Monochoria vaginalis
Synonyms: Heartshape false pickerelweed, Monochoria, Pickerelweed



Photo courtesy of IRRI and University of Queensland

Habitat

Irrigated fields

Affected crops

Mostly irrigated rice

Distribution

Worldwide

Description

The stem is slightly erect and fleshy. The leaves are heart-shaped, shiny, and with rounded bases. The flower head is clustered and composed of up to 25 flowers. The flowers are lilac or violet-blue. The roots are submerged under water or rooted in the mud and the rest parts are above the water surface. The plant is propagated by seeds or whole plants.

Effects and impacts

Monochoria can reduce rice yield as high as 82%, when left uncontrolled. Sixty individual plants/sq. m. can reduce yield by up to 35% (Rice IPM, 2001).

In India, the plant is used as vegetable and the roots are used for medicinal purposes.

Studies show that when the weeds infest some rice fields in South Korea, they are found to be resistant to Bensulfuron-methyl (Weed Science, 2005).

Methods of control

1. Proper seed selection
2. Regular field monitoring
3. Thorough land preparation by plowing and harrowing
4. Keeping seedbeds free of weeds
5. Hand weeding
6. Crop rotation

External links

• PAN Pesticide Database. Bensulfuron methyl - Identification, toxicity, use, water pollution potential, ecological toxicity and regulatory information. http://www.pesticideinfo.org/Detail_Chemical.jsp?Rec_Id=PC33787
• Weed Science. Bensulfuron-methyl. http://www.weedresearch.com/summary/ChemFamilySum.asp?lstActive=52&btnSub1=Go&lstHRAC=
• Weed Science. GroupB/2 resistant arrowleafed monochoria. http://www.weedscience.org/Case/Case.asp?ResistID=151

References

• IRRI & Queensland University. (2001): Rice IPM. An interactive information and identification system for integrated pest management in rice. University of Queensland and IRRI.
• Moody, K.; Munroe, C.; Lubigan, R.; Paller , E. (1984): Major weeds of the Philippines. University of the Philippines, Los Baños. Laguna, Philippines.
• Reissig, W.; Heinrichs, E.; Litsinger, J.; Moody, K.; Fiedler, L.; Mew, T.; Barrion, A. (1986): Illustrated guide to integrated pest management in rice in tropical Asia. IRRI. Los Banos, Laguna, Philippines.