Abstract
An important goal for mycoherbicide research and development is to produce a viable and consistently efficacious product with a long shelf life. The efficacy of 5-year-old Pesta granules of Fusarium oxysporum Foxy 2 in comparison to freshly prepared Pesta granules in controlling the root parasitic weed Striga hermonthica was studied. Pesta granules were made by encapsulating fresh chlamydospores of Foxy 2 in a matrix composed of durum wheat-flour, kaolin, and sucrose. Samples of Pesta granules were stored at 4°C over a period of 5 years. Two g per pot (4 kg soil) of each granular preparation were incorporated pre-planting to sorghum together with Striga seeds. The application of the 5-year-old Pesta granules (2.4 × 105 Cfu g–1) as well as the freshly prepared Pesta granules (1.5 × 106 Cfu g–1) of Foxy 2 sharply reduced the total number of healthy emerged S. hermonthica shoots and/or caused severe disease on the emerged Striga plants compared to the control. None of the emerged plants reached flowering stage in Foxy 2-treated pots, whereas in the control treatment 19.2% of the Striga plants flowered. Maximum efficacy (i.e., 100% reduction in healthy emerged Striga shoots compared to the control treatment) of both Pesta preparations in controlling Striga was achieved, indicating similar potential of both old and fresh formulations. The result revealed that encapsulation of Foxy 2 into “Pesta” formulation did not adversely affect its virulence and efficacy even after 5 years of storage under cold conditions. This represents an important attribute to support wide-scale deployment, storage, handling and delivery of Striga-mycoherbicides Pesta technology in Africa.
Zusammenfassung
Ein wichtiges Ziel der Mycoherbizid-Forschung und -Entwicklung ist die Produktion eines lagerfähigen und konstant wirksamen Produkts mit langer Haltbarkeit. Die Wirksamkeit eines 5 Jahre alten Pesta-Granulats von Fusarium oxysporum Foxy 2 gegenüber der wurzelparasitären Samenpflanze Striga hermonthica wurde mit frisch produziertem Pesta-Granulat verglichen. Das Granulat wurde durch Einkapselung frischer Chlamydosporen von Foxy 2 in einer Matrix aus Hartweizen-mehl, Kaolin und Saccharose hergestellt. Proben dieses Granulats wurden fünf Jahre lang bei 4°C gelagert. Zwei g jeder Granulatprobe pro Topf (4 kg Erde) wurden vor der Pflanzung von Sorghum zusammen mit Striga-Samen mit der Erde vermischt. Sowohl das 5 Jahre alte (2,4 × 105 Cfu g?–1) als auch das frisch hergestellte (1,5 × 106 Cfu g?–1) Pesta-Granulat von Foxy 2 verminderten die Anzahl keimender S. hermonthica deutlich und/oder erzeugten schwere Krank-heitssymptome an den gekeimten Pflanzen. Keine der Striga-Pflanzen entwickelte sich in den mit Foxy 2 behandelten Töpfen bis zur Blüte, während in den Kontrolltöpfen 19,2% der Pflanzen blühten. Eine maximale Wirkung (d.h. eine 100%ige Verminderung gesunder Striga-Pflanzen im Vergleich zur Kontrolle) wurde mit beiden Pesta-Präparaten erzielt, was auf ein ähnliches Wirkungspotenzial frischer und älterer Formulierungen hindeutet. Die Ergebnisse zeigen, dass eine Verkapselung von Foxy 2 mit einer Pesta-Formulie-rung die Virulenz selbst nach fünfjähriger Kühllagerung nicht vermindert. Diese Eigenschaft kann bei der großflächigen Entwicklung, Lagerung, Handhabung und dem Einsatz von Striga-Mycoherbiziden mit Hilfe der Pesta-Technologie in Afrika von Nutzen sein.
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Elzein, A., Kroschel, J. & Cadisch, G. Efficacy of Pesta granular formulation of Striga-mycoherbicide Fusarium oxysporum f. s p. strigae Foxy 2 after 5-year of storage. J Plant Dis Prot 115, 259–262 (2008). https://doi.org/10.1007/BF03356274
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DOI: https://doi.org/10.1007/BF03356274
Key words
- biological weed control
- encapsulation
- Fusarium oxysporum
- mycoherbicide
- shelf life
- Striga hermonthica
- virulence