Abstract. All the tested compounds used in carrot control against Alternaria blight reduced the leaf infestation. In the field conditions the best protective efficacy had standard fungicide Amistar 250 SC, slightly poorer had Biosept 33 SL. However in laboratory conditions the size of necrosis of petioles was the smallest, after the application of Biosept 33 SL.

The application of natural compounds in protection
of carrot against Alternaria blight

Summary

In the years 2005 and 2006 the influence of protection on infestation of carrot cultivar ‘Koral’ by Alternaria leaf blight in field and in laboratory conditions was studied. During the studies Bioczos (extract of garlic), Biochokol 020 PC (polymer of chitosol) and Biosept 33 SL (33% extract of grapefruit) were used. As the standard fungicide was Amistar 250 SC (azoxystrobin 250 g·dm^-3). The tested substances during the vegetation period were used three times as spray. The results of health status of carrot leaves analysis showed, that each of the tested compounds used in carrot protection reduced the leaf infestation. The best efficacy in control of Alternaria blight in field conditions showed Amistar 250 SC and Biosept 33 SL. In laboratory conditions slightly better was Biosept 33 SL, which significantly limited the size of necrosis of petioles infected by Alternaria radicina, A. alternata, and A. chartarum.