Evaluation of non-chemical agents for control of black rot on grape vine (Guignardia bidwellii) in organic farming

摘要

Originating from the Americas, black rot of grapes caused by the ascomycete Guignardia bidwellii (conidial state: Phyllosticta ampelicidd) was introduced to Europe in 1885. Vineyards in Germany were seldom affected until 2002, when the disease was first discovered in the Mosel valley. In 2004 a severe epidemic occurred in parts of the Mosel wine growing area, and in recent years the disease has appeared regularly. The epidemiology of black rot is not fully understood, and the level of resistance in commercial varieties is not sufficiently known. While in conventional wine growing black rot is controlled by a number of chemical fungicides, organic farmers have little at hand to avoid or minimize the losses from this disease. Copper sprays at the lowrates allowed in organic farming have proven ineffective. Therefore, agents for control of black rot specifically in organic farming are urgently needed. In 2006, a project integrating preventative measures, resistance management and disease control wasinitiated with the aim to improve the current situation of black rot control in organic farming. In the following, the results of greenhouse tests with alternative control agents, like commercially available bio-fertilisers, registered plant strengthening products and experimental agents of natural origin such as microorganisms and plant extracts are reported.