The basis of our black rot model is the model published by Spotts (Spotts. R. A. 1977. Effect of leaf wetness duration and temperature on the infectivity of Guignardia). Through discussions with Daniel Molitor we modified the original Spotts model toward a model seperating into light, moderate and severe infections similar to the design of Apple Scab models. (Daniel Molitor: Untersuchungen zur Biologie und Bekämpfung der Schwarzfäule (Guignardia bidwellii) an Weinreben. Dissertation Justus-Liebig-Universität Gießen, 2009. ).
An infection just fullfilling the Spotts criteria is rated to be a light infection. Infections fullfilling the Spotts criteria by 150% are rated to be moderate and infection fullfilling the Spotts criteria by 200% are rated to be severe.
The model shows the infection dates for light, moderate and severe infections. When 100% of an infection has been fullfilled conditions for spore discharge, germination and infection of the plant tissue have been given. The severity of the infection depends on the time period of optimal temperature and wetness period of the fungus. In dependence of the infection pressure the infections should be covered preventative or a curative spray has to be applied short after the infection. In the moderate semi arid climate of the Mosel or the most Austrian wine growing areas a spray after light infections occurr, would not be needed.