VLIV ÚČINNÉ LÁTKY FUNGICIDU (IN VITRO) NA RŮST MYCELIA, KLÍČENÍ KONIDIÍ A SKLEROCIÍ HOUBY Botrytis convoluta

Abstract

In the years 2005–2007 in a collection of 527 cultivars of tall large-flowered irises (Iris × barbata group Elatior) in the Botanical Garden and Arboretum of MZLU in Brno the fungus Botrytis convolute in­fes­ted the plants. Within three years, as a consequence of the infestation, some cultivars showed symptoms of poor growth, in isolated cases the plants died. Control of irises against this pathogen has not yet been satisfactorily solved. At the present time no fungicides against B. convolute have been re­gis­te­red, only fungicides protecting ornamental plants against Botrytis cinerea. We explored the effect of seven active substances – captan, carbendazim, fenhexamid, iprodione, mancozeb, pyrimethanil and tolylfluanid (in vitro) in four different concentrations on the growth of the mycelia, germination of conidia and sklerotia. We evaluated the germination of B. convoluta conidia over 24 and 48 hours, my­ce­lium growth and germination of sclerotia over 5 days. In control plants the germination capacity of conidia over 48 hours reached 98–99 %. Over 24 hours all the tested concentrations of preparations containing the active substances tolylfluanid and captan markedly affected the germination of conidia; their effectiveness ranged between 88 and 100 %. All the active substances in the registered concentration (mancozeb 0.2 %, tolylfluanids 0.2 %, carbendazim 0.2 %, pyrimethanil 0.25 %, ipro­dio­ne 0.3 %, fenhexamid 0.15 % and captan 1 %) prevented, or considerably reduced, the growth of B. convoluta mycelia (98.8–100 %). The active substances carbenazim, iprodione and fenhexamide very effectively (96.4–100 %) inhibited mycelium growth, at all the tested concentrations. Without an addition of fungicide all the sclerotia on the nutrient solution germinated and formed a mycelium disk 36 mm in diameter. The active substance carbendazim inhibited sklerotia germination at all concentrations; the other active substances, i.e. tolylfluanid, pyrimethanil, iprodione and fenhexamid did not prevent mycelium growth, or the formation of conidiophores with conidia.