Research Summary Abstract
At the IR-4 Ornamental Horticulture Program Workshop in 2013, leaf spots and anthracnose efficacy was selected as a high priority project to expand the knowledge and list of fungicides available to growers for these diseases. In addition to research collected through the IR-4 program, this summary includes a review of experiments conducted from 1987 to 2015 on ornamental horticulture crops. Species tested included: Alternaria alternata, Apiognomonia quercina, Cercospora cornicula, Cercospora lythracearum, Colletotrichum navitas, Colletotrichum sp., Corynespora cassiicola, Diplocarpon rosae, Discula destructiva, Drechslera setariae, Elsinoe corni, Entomosporium mespilii, Marssonina populi, Myrothecium roridum, Phaeocryptopus qaeumannii and Septoria sp. During this time period, numerous products representing 45 active ingredients were tested as foliar applications against these species causing various leaf spots and anthracnose. Most products are registered and commercially used. Although there were insufficient data for definitive conclusions, two new products that were included, Orkestra, and Mural, looked promising. Compass, Pageant and Palladium provided variable efficacy depending on species. F9110, Proud 3, MBI-110, Milsana, Disarm, SP2770, SP2773 and ZeroTol were generally ineffective. Limited data on other relatively new products (NUP 09092, S2200, Tourney and Trinity) were inconclusive. The established standards Daconil and Eagle generally provided excellent efficacy; Chipco 26019 provided good efficacy, and Medallion provided variable efficacy depending on species. The data from these trials suggest that the effectiveness of some fungicides in controlling leaf spots and anthracnose is variable, depending on the pathogen species.