ISHS Acta Horticulturae 547: III International Symposium on Rose Research and Cultivation
EVALUATION OF REDUCED RISK AND OTHER BIORATIONAL FUNGICIDES ON THE CONTROL OF POWDERY MILDEW ON GREENHOUSE ROSES |
| Authors: | S. Tjosvold, S.T. Koike |
| Keywords: | reduced-risk, biorational, fungicide, powdery mildew, rose, Rosa hybrida |
| Abstract:
Commercial rose growers in the United States are under increasing pressure to use reduced-risk pesticides that have minimum re-entry intervals following application. Along with obvious environmental pressures to reduce toxic pesticide use, the growers are operating under a special exemption that allows re-entry within a pesticide re-entry restriction period. It is therefore of paramount importance to develop and test reduced risk pesticides that have minimal re-entry intervals following their application. Powdery mildew may account for 40% or more of the pesticide volume applied to rosecrops and therefore it is important to find new fungicides to control this serious disease. The experiment reported here evaluated the efficacy of many reduced-risk fungicides on rose powdery mildew, Sphaerotheca pannosa. Phytotoxicity effect was also evaluated because some of these fungicides are known to have considerable potential to cause adverse plant reactions. Fungicide treatments consisted of representatives of several fungicidal groups: strobilurins, bicarbonate salts, horticultural oils, biocontrol agents, contact chemicals, and activated resistance compounds. The strobulurins, as a group, performed well without causing loss in plant vigor. Many other products were moderately effective on mildew control but caused mild to severe loss in vigor due to phytotoxicity. | |
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