On farm trials about the suppressiveness of compost against Rhizoctonia solani in organic potato cultivation (2006-2012)

• Oliver Hensel, Agricultural Engineering
• Maria R. Finckh, Ecological Plant Protection

• • Landwirtschaftskammer Niedersachsen
  • Fa. Ökokontor und Fa. Europlant (Kartoffelzüchter)
  • Fa. Grimme, Damme

2006 - 2012

Black scurf of potato is caused by the fungus Rhizoctonia solani and has become a steady problem in potato production. It is visible through various symptoms which can lead to substantial losses of quality and quantity. The pathogen can survive on a long term either in soil or on tubers. While chemical pesticides are common in conventional production systems successful control strategies are nearly unavailable for organic growers. As seed potatoes from organic propagation (quite often infected) are compulsory this has even worsened the problem. Since 2006 our group has successfully performed research work to control the pathogen with strip application of composts while planting potatoes. Particularly mix composts from biogenic waste (source separated) or yard waste (shredded shrubs and trees) or pure yard waste composts showed significant reductions of the disease between 30-50% in all symptoms of the disease (black scurf, dry core, malformed tubers). This has resulted in explicitly increased marketable yields. In 2008 at several sites we could reproduce the data form the preceding years, in 2009 these were also confirmed form other groups at different sites. In 2010 and 2011 we checked with composts from commercial composting plants if the strategy was continuing reproducible. In 2012 our main interest is the assessment of composts from commercial plants with different decomposition levels and different carbon content at 3 sites of the experimental farm (Staatsdomäne Frankenhausen). These investigations are following the results of the past years as we could see that model-composts were more effective than composts from the practice and apart from this stronger site specific deviations resulted in weaker effects compared to the results from 2006 to 2009. We will quantify both the symptoms during the season and on harvested tubers as well as yield.

A further focus was put on the development of a technical solution for the strip application technology in collaboration with Grimme (Damme). Meanwhile a prototype was developed which was checked during 2011. The machine is equipped with a compost bunker and different tools for the strip application of composts. At the moment the bunker will be modified to avoid some problems with bridge-set ups of the composts.

In addition our running work is also focused on the identification of mechanisms of the composts to control the disease and the characterization of successful material in order to give comprehensible advice for compost productions.

• Christian Bruns
• Tina Behrens
• Elmar Schulte-Geldermann
  (till the end of 2008)

• Bohne, B., O. Hensel & C. Bruns (2011). Reihenapplikation von Komposten im Kartoffelbau. Kartoffelbau, 4/2011, 42-45.
• Bruns, C., J. Heß, Maria R. Finckh, O. Hensel & E. Schulte Geldermann. (2010). Kompost gegen den Pilz. Brandenburger Bauern Zeitung, 04/2010
• Bruns, C., J. Heß, Maria R. Finckh, O. Hensel & E. Schulte Geldermann (2009). Komposteinsatz gegen Rhizoctonia solani im Ökologischen Kartoffelbau. Kartoffelbau, 3/2009, 84-88.
• Schulte-Geldermann, E., Schüler, C., Hensel, O., Heß, J., Finckh, M.R. & Bruns. C. (2008): Control of Rhizoctonia solani in potatoes with a new application technique of suppressive composts in organic potato production In: J.G. Fuchs, T. Kupper, L. Tamm & K. Schenk (Eds.). Compost and digestate: sustainability, benefits, impacts for the environment and for plant production. Proceedings of the international congress CODIS 2008. February 27-29, 2008, Solothurn, Switzerland. FiBL, FiBL Report, 1st Edition, 2008, 325 Seiten, ISBN 978-3-03736-016-3.
• Schulte-Geldermann, E., Hensel, O., Finckh, M. R., & Bruns, C. (2008). Einsatz von Komposten als Reihenapplikation zur Reduzierung von Rhizoctonia solani an Kartoffeln - Ergebnisse aus Feldversuchen 2006/2007. 56. Deutsche Pflanzenschutztagung in Kiel, 22.-25.Sept. 2008 Mitt. Julius Kühn-Institut, 417, 250.
• E. Schulte Geldermann, C. Schüler, O. Hensel, J. Heß, Maria R. Finckh & C. Bruns (2007). Einsatz von Komposten als Reihenapplikation zur Reduzierung von Rhizoctonia solani an Kartoffeln – Ergebnisse aus Feldversuchen 2006/2007. In: Kühne et al. (Hrsg.) Pflanzenschutz im ökologischen Landbau – Probleme und Lösungsansätze – 12. Fachgespräch. Anwendung von Pflanzenschutzmitteln und innovativer Verfahren im Ökologischen Landbau neue Wirkstoffe und Applikationstechnik. Berichte aus der BBA, Heft 141. Braunschweig 2007.