Search

Black rot on grapevine is a fungal disease caused by Phyllosticta ampelicida (syn. Guignardia bidwellii) affecting grape leaves as well as clusters. A novel black rot decision support system termed VitiMeteo Black rot was assembled based on existing sub-models and incorporated into the established VitiMeteo forecast and decision support platform. Based on local weather data and a 5-day weather forecast, VitiMeteo Black rot simulates the relative susceptibility of grape clusters, the occurrence and severity of infection events as well as the duration of incubation periods. Data sets obtained in extended international (14 case studies; eight monitoring locations; 11 cultivars; seven countries in Europe and North America) field monitoring campaigns in 2012 and 2013 were used to evaluate the model predictions of newly expressed symptoms on leaves. In the case of the Vitis vinifera cultivars, on average 26.3 disease assessments took place per season. On average, 9.9 predictions were classified as true positive, 8.0 as true negative, 5.2 as false positive and 3.2 as false negative. Model precision, sensitivity and accuracy were on average 64, 77 and 67 %. Potential reasons for false positive and false negative predictions are discussed. VitiMeteo Black rot is freely available for several locations in Germany, Luxembourg and Austria on the internet via the VitiMeteo platform and might be expanded to other regions in the future.

Germination of Phyllosticta ampelicida pyc- nidiospores was followed from attachment through development of mature, highly melanized appresso- ria. Using time- lapsed video microscopy, it was de- termined that mature appressoria formed within 6 hours of attachment of the spores on hydrophobic substrata. Pycnidiospores germinated in the presence of tricyclazole did not produce pigmented appresso- ria indicating that the darkening agent is melanin, which in normal appressoria reached maximum lev- els within 6 hours following germination. Pycnidio- spores were binucleate. Prior to development of the septum separating the pycnidiospore and germ tube from the appressorium, the two nuclei divided mi- totically and three of the four resulting nuclei mi- grated into the appressorium. The fourth nucleus re- mained in the pycnidiospore where it degraded ul- timately. Mature appressoria formed penetration pegs capable of penetrating polycarbonate.

Phyllosticta ampelicida, the causal agent of black rot of grape, is one of the most damaging fungal pathogens in viticulture in North America. The interactions of the pathogen with host leaf tis- sues were studied to better understand the behavior

The presence and extent of the extracellular matrix surrounding pycnidiospore germlings and appressoria of Phyllosticta ampelicida was assessed using cryo-scanning and light microscopy. Conidia of ...