A comparison of management regimes for one-year rotational set-aside within a sequence of winter wheat crops, and of growing wheat without interruption. 2. Effects on vegetation and weed control

Six management regimes for I-year set-aside were compared with continuous winter wheat for their effects on weed control in two following test crops of winter wheat. The experiment was repeated in each of three years (1989-91) on predominantly sandy loam soils in eastern England. The weed flora was dominated by Poa spp., Stellaria media, Matricaria spp., Chenopodium album and volunteer crops, predominantly wheat. Managing set-aside by allowing natural regeneration and cutting it 2-4 times during the growing season resulted in fewest weeds in the following wheat crop. It was also a low cost option. Winter wheat, despite the application of herbicides, was not as effective in minimizing weeds in the winter wheat test crops as the best set-aside options. An Italian ryegrass cover crop set seed despite being cut 2-4 times per year. The only serious weed infestation arising in following wheat crops was from volunteer ryegrass in the second wheat following set-aside. The effects of management in the set-aside year were generally greater in the second of the following wheats than in the first.