Wheat volunteers in Lolium perenne effects on Gaeumannomyces graminis var tritici carryover and takeall

Abstract

Crop rotations can be used to manage the buildup of inoculum of Gaeumannomyces graminis var tritici (Ggt) an important pathogen that causes takeall in wheat crops This study investigated whether the value of a perennial ryegrass (Lolium perenne) break crop is impaired by the presence of wheat volunteers Soil Ggt concentrations after perennial ryegrass without wheat volunteers were approximately 20 of those with wheat but perennial ryegrass was less effective than fallow at reducing soil Ggt Wheat volunteers reduced the value of a perennial ryegrass break when they were present at densities of 40 volunteers/m2; below this density soil Ggt concentrations and takeall incidence levels were similar to the perennial ryegrass only treatment After the volunteer season under low volunteer densities (115 plants/m2) Ggt concentrations declined to below the detection level (< 5 pg DNA) within 1 year