Some crops need to be both heavy rolled and wild oat sprayed before plant growth regulator (PGR) application. It is important that there are at least a ten-day gap between each of these operations. For many the sequence will be closing and immediately after heavy roll; followed ten+ days later by a wild oat spray; followed by PGR after another ten+ days.

Where there hasn’t been enough grazing pressure on crops before closing, controlling growth with split rates of PGR is an option. However the first application should be applied at GS31 and this becomes difficult if both heavy rolling and wild oat spraying are required. Topping to close may be needed in this situation.

Nitrogen (N): Apply about half the total spring N at closing and the other half about PGR is not critical. Total spring N application is calculated as:

Applied N (kg/ha) = 175 - soil mineral N [0-30 cm] for perennial ryegrass: For annual ryegrass the amount required is probably 20 kg/ha less than for perennial. FAR says ‘probably’, as it has less field data than the 26 trials used to predict perennial ryegrass requirements.

Source: FAR