Frutogard® is an algae extract containing potassium phosphite (Potassium Phosphonat in German). The use of copper products is permitted in organic viticulture, however copper only provides a preventative action and research is now being undertaken to test the effectiveness of low copper formulations and alternatives to copper for organic growers. A four year trial 2004-2007 in Germany by Uwe Hofmann showed that it is possible to use sprays with a reduced copper content (1.5–2 kg/ha/year) in combination with Myco-Sin, an acidified clay mineral product, and plant strengtheners including algae extracts, plant extracts, and phosphonate. In years with low and medium disease pressure a good level of control was achieved. A combination of copper hydroxide at low rates with 2-3 applications of K-Phosphonate (Frutogard®) between flowering and fruit set provided a high level of protection.
‘Optimisation of downy mildew (Plasmopara viticola) control in organic viticulture with low copper doses, new copper formulations and plant strengtheners, results of 20 years of on farm research,’ by Uwe Hofmann of ECO-CONSULT, Geisenheim, Germany.