Journal of Chemical Ecology (2002) 28, 1871-1885

Zeyaur R. Khan, Ahmed Hassanali, William Overholt, Tsanuo M. Khamis, Antony M. Hooper, John A. Pickett, Lester J. Wadhams and Christine M. Woodcock (2002)
Control of witchweed Striga hermonthica by intercropping with Desmodium spp., and the mechanism defined as allelopathic
Journal of Chemical Ecology 28 (9), 1871-1885
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.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Zeyaur R. Khan, Ahmed Hassanali, William A. Overholt, John A. Pickett, Antony M. Hooper

Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Striga hermonthica (weed)	Maize/corn (Zea mays)	Kenya