Tropentag, October 11 - 13, 2006 in Bonn "Prosperity and Poverty in a Globalized World – Challenges for Agricultural Research"

Enhancing Striga Management Using Pesta Granular Mycoherbicidal Formulations: Synergy Between Striga-mycoherbicides and Nitrogen Fertiliser

¹University of Hohenheim, Institute of Plant Production and Agroecology in the Tropics and Subtropics, Germany
²International Potato Center, Integrated Crop Management Division, Peru
³Ahmadu Bello University, Institute for Agricultural Research, Nigeria

Abstract

Root parasitic weeds of the genus Striga constitute a major biotic constraint to staple food production in Africa, and consequently aggravate hunger and poverty. An integrated approach in which biocontrol represents an important component, appears to be the ideal strategy for reducing Striga infestation. Therefore, the synergistic effect between Striga-mycoherbicide Fusarium oxysporum (isolates Foxy 2 and PSM 197) and nitrogen fertiliser (urea) formulated into Pesta granules, in controlling Striga was investigated under glasshouse conditions. Pesta granules were made by encapsulating the inoculum of fungal isolates and urea in a matrix composed of durum wheat-flour, kaolin, and sucrose. Two g of each granular preparation were incorporated pre-planting per pot (4 kg soil) together with Striga seeds. An apparent synergistic effect between Foxy 2, PSM197 or of their mixtures and urea, encapsulated into Pesta granules, in controlling Striga was observed. All Pesta combinations totally inhibited or significantly reduced the emergence of Striga compared to the control, where a steep increase in Striga emergence was recorded. Even all the few emerged shoots in the pots treated with fungal mycoherbicide/urea combinations became diseased. None of the emerged plants reached flowering stage, whereas in the control treatment 13% of the Striga plant flowered. All Pesta preparations were very effective, with ≥92 % efficacy, indicating similar excellent potential of Striga control. When considering the improvement of the sorghum plants, however, the highest increase in the total biomass (85%) and in the panicle yield (40%) was achieved with preparation containing the mixture of Foxy2+PSM197+2g urea, confirming the synergistic effect of the fungal isolates and urea. However, the significant reduction in Striga emergence and flowering as a result of combining mycoherbicides and urea is an important feature to prevent further Striga distribution and infestation. These findings are highly relevant to the realisation of an integrated Striga control approach adoptable and applicable by subsistence farmers in Africa.

Keywords: Fusarium oxysporum, Integrated approach, Mycoherbicide, Nitrogen fertiliser, parasitic Weed biological control, Striga hermonthica

Contact Address: Abulegasim Elzein, University of Hohenheim, Institute of Plant Production and Agroecology in the Tropics and Subtropics, Garbenstr. 13, D-70599 Stuttgart, Germany, e-mail: gasimuni-hohenheim.de