GLYPHOSATE AND FUNGICIDE EFFECTS ON CERCOSPORA LEAF SPOT IN FOUR GLYPHOSATE-RESISTANT SUGAR BEET (BETA VULGARIS) VARIETIES

摘要

Glyphosate continues to be a valuable weed management tool for growers with the introduction of glyphosate-resistant crops. Michigan sugar beet growers were quick to adopt glyphosate-resistant sugar beet with 98% of Michigan's sugar beet area plantedto glyphosate-resistant varieties by 2009. Cercospora leaf spot (CLS), caused by Cercospora beticola Sacc, is one of the most important foliar diseases of sugar beet. When severe it can reduce root and sugar yield and may reduce viability of roots in storage. CLS is managed by a combination of tillage, rotation, host plant resistance and fungicides. The objectives of this research were to investigate potential interactions between a conventional herbicide standard-split program and glyphosate programs with fungicide applications of a standard CLS management program on the development of CLS in four glyphosate-resistant sugar beet varieties with a range of tolerance to CLS.Controlled field experiments were conducted in 2008 and 2009 to determine if glyphosate and glyphosate-fungicide combinations improved the management of CLS in four commercial varieties of glyphosate-resistant sugar beet.