Survey of root rot diseases of sugar bett in Central Greece

An extensive survey was conducted during the summer and autumn of 2004 in sugar beet fields in the area of Larissa, Thessaly region, with plants showing symptoms of root rot diseases. The aim of the monitoring was to identify the causal agents of root rot diseases. In total, 76 sugar beet fields were surveyed and 5-10 diseased roots were examined from each field. Isolations, carried out on PDA, showed that two main fungal pathogens causing root rot were Rhizoctonia solani and Phytophthora cryptogea. The former was isolated in 46% of the fields and the latter in 38% of the fields. In addition, Rhizopus stolonifer, Fusarium spp., Scerotium rolfsii and Rhizoctonia violacea were isolated in 14%, 7%, 4% and 1% of the fields respectively. In most of the surveyed fields only one pathogen species was isolated and only in a few of them more than one fungal species was identified

Root rot diseases of sugarbeet (Beta vulgaris L) as affected by defloliation intensity

The aim of this work was to study the effect of sugar beet re-growth after water stress defoliation on root rots of three cultivars (Europa, Rival Corsica), which were spring sown in Thessaly, central Greece, for two growing seasons (2003-04). At the beginning of July, sugar beets were subjected to water deficit with irrigation withholding. A month later, three defoliation levels (control - C, moderate - MD, severe - SD) and irrigation were applied. Thus, sugar beets were forced to re-grow and three harvests (15, 30 and 40 days after defoliation - DAD) were conducted. Rotted roots per hectare were counted and pathogens were identified. Data were analyzed as a four-factor randomized complete block design with years, defoliation levels, sampling times and cultivars as main factors. The number of rotted roots was increased with the defoliation level and was significantly higher for SD sugar beets (3748 roots ha–1). No significant differences were found between C and MD treatments (1543 and 2116 roots ha–1, respectively). Rival was the most susceptible cultivar to root rots. Sugar beets were more susceptible to rotting 15 and 40 DAD (2778 and 2998 roots ha–1). The causal agents of root rots were the fungi, Fusarium spp., Rhizopus stolonifer, Macrophomina phaseolina and Rhizoctonia solani