Evaluation of chemical and biological fungicides for controlling brown leaf blotch in horse chestnut nurseries

Horse chestnut (Aesculus hippocastanum L.) seedlings are affected by brown Leaf Blotch caused by the fungus Guignardia aesculi (Peck) Stewart. The sprouts and seedlings of horse chestnut are more susceptible to the disease. It is necessary to effectively protect sprouts and seedlings from the damage by diseases during the stages of plant development. Timely treatment of plants with modern systemic fungicides allows them to keep their leaves and shoots healthy, which allows the normal process of photosynthesis in plants, resulting in stable growth and development of plants. Experiments were conducted to test synthetic chemical fungicides and biofungicides belonging to the group of triazoles and strobilurins against brown Leaf Blotch disease in one- and two-year-old seedlings of horse chestnut. Treatments with fungicides were carried out in the nurseries in 3 replications for each option, the biological efficiency of the used preparations was determined by comparing the disease severity with the control option. None of the fungicides tested in the experiment showed biological efficiency higher than 75 per cent. Among the fungicides, relatively high biological efficiency was noted for the preparations Rayok EC (67.8% and 74.6%) and Altis SC (66.3% and 73.4%). Biofungicides Orgamika C, Fitosporin and Orgamika F did not show high biological efficiency (15.2-29.6%) against Guignardia Leaf Blotch. It was found that the disease severity of Guignardia brown Leaf Blotch of Horse chestnut was higher in the Angren district than in the Zangiata district of the Tashkent region.