Influence of mancozeb fungicides, chlorothalonil, manganese and zinc on bentgrass color and disease incidence

Manganese (Mn) and Zinc (Zn) are important plant mi-cronutrients involved in chlorophyll synthesis, photosynthesis, various enzyme systems, and possibly auxin synthesis, Mancozeb-containing fungicides deliver small quantities of manganese (Mn) and zinc (Zn) to turf as part of their active ingredient. This field study determined that two mancozeb-containing fungicides, Fore 80 WP and 4 Flowable Mancozeb, increased leaf tissue levels of Mn and Zn in Penncross’ creeping bentgrass (Agroslis stoloniferous Huds.) more than Daconil Ultrex (a chlorothalonil fungicide) having Mn and Zn added to it, or foliar]y applied Mn/Zn with or without a spreader-binder (Latron CS-7). Turf color improved through the use of all fungicide treatments, as well as with the use of Mn/Zn. The Mn/Zn solution without the spreader-binder was as effective as Fore 80 WP in reducing dollar spot (Sckrotinia homoeocar-pa F.T. Bennett) infection, and was better than 4 Flowable Mancozeb. The Mn/Zn solution, with or without Latron CS-7, also reduced the severity of red leaf spot (Drechslera erythrosphila [Drechs] Shoemaker).