Journal of Chemical Ecology

, Volume 28, Issue 9, pp 1871–1885

Control of Witchweed Striga hermonthica by Intercropping with Desmodium spp., and the Mechanism Defined as Allelopathic

  • Zeyaur R. Khan
  • Ahmed Hassanali
  • William Overholt
  • Tsanuo M. Khamis
  • Antony M. Hooper
  • John A. Pickett
  • Lester J. Wadhams
  • Christine M. Woodcock
Article

DOI: 10.1023/A:1020525521180

Cite this article as:
Khan, Z.R., Hassanali, A., Overholt, W. et al. J Chem Ecol (2002) 28: 1871. doi:10.1023/A:1020525521180

Abstract

During investigations into the control of insect damage to maize crops in subsistence farming in Kenya, which involved intercropping with repellent plants, the fodder legumes silverleaf (Desmodium uncinatum) and greenleaf (D. intortum) were also found to reduce dramatically the infestation of maize by parasitic witchweeds such as Striga hermonthica. This effect was confirmed by further field testing and shown to be significantly greater than that observed with other legumes, e.g., cowpea, as were the concomitant yield increases. The mechanism was investigated, and although soil shading and addition of nitrogen fertilizer showed some benefits against S. hermonthica infestation, a putative allelopathic mechanism for D. uncinatum was observed. In screenhouse studies, a highly significant reduction in S. hermonthica infestation was obtained when an aqueous solution, eluting from pots in which D. uncinatum plants were growing, was used to irrigate pots of maize planted in soil seeded with high levels of S. hermonthica. Growth of the parasitic weed was almost completely suppressed, whereas extensive infestation occurred with the control eluate. Laboratory investigations into the allelopathic effect of D. uncinatum, using samples of water-soluble chemical components exuded from cleaned roots, demonstrated that this involved a germination stimulant for S. hermonthica and also an inhibitor for haustorial development.

AllelopathymaizeStrigaDesmodiumnitrogenshadingsilverleafgermination stimulantsuicidal germination

Copyright information

© Plenum Publishing Corporation 2002

Authors and Affiliations

  • Zeyaur R. Khan
    • 1
  • Ahmed Hassanali
    • 2
  • William Overholt
    • 2
  • Tsanuo M. Khamis
    • 3
  • Antony M. Hooper
    • 4
  • John A. Pickett
    • 4
  • Lester J. Wadhams
    • 4
  • Christine M. Woodcock
    • 4
  1. 1.The International Centre of Insect Physiology and EcologyMbita Point Field StationMbita, S. NyanzaKenya
  2. 2.The International Centre of Insect Physiology and EcologyNairobiKenya
  3. 3.Chemistry DepartmentJomo Kenyatta University of Agriculture and TechnologyNairobiKenya
  4. 4.Biological and Ecological Chemistry DepartmentIACR-RothamstedHarpenden, HertfordshireUnited Kingdom