Intensity of Anthracnose on Three Wintercreeper Euonymus Cultivars as Influenced by Fungicide Program

Abstract

Abstract Plants of three cultivars of wintercreeper euonymus (Euonymus fortunei (Turcz.) Hand.-Mazz. ‘Emerald Gaiety’, ‘Emerald ‘n Gold’ and ‘Canadale Gold’) in containers were sprayed at 7-or 14-day intervals depending on label directions with mancozeb, propiconazole, or thiophanate methyl alone or in tank mixes of two fungicides to determine efficacy in controlling anthracnose symptoms caused by Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. Each fungicide was applied at the maximum label rate and half the maximum label rate when applied alone or at the maximum label rate when applied in combination. Plants were rated for disease symptoms monthly at two sites in 2002 and at one site in 2006. At Stillwater, disease ratings were typically lowest on ‘Emerald Gaiety’ and highest on ‘Emerald ‘n Gold’ on all rating dates in both years. Plants of all three cultivars and in all fungicide treatments at Stillwater had sufficient disease symptoms in July, August and September of both years to be considered nonsalable. When applied alone, mancozeb typically provided better anthracnose control than propiconazole or thiophanate methyl. Disease ratings from plants receiving any fungicide mixture were generally similar to those of plants receiving mancozeb alone. At Park Hill, disease ratings differed among cultivars only in August and September, and ratings did not differ among fungicide treatments on any rating date. Disease severity was substantially less at Park Hill than Stillwater in 2002, presumably the result of greater shade intensity and lower temperatures.