K.F. LOWE1, T.M. BOWDLER1 and J.C. MULDER2
1Department of Primary Industries, P.O. Box 96, Ipswich, Qld, Australia 4305.
2Department of Primary Industries, Oonoonba Veterinary Laboratory, P.O. Box 1085, Townsville, Qld, Australia 4810.
The effect of four sowing times, early March, mid March, late March and mid April, on the establishment, growth pattern and rust incidence of annually sown ryegrass cultivars (Lolium spp.) was investigated in irrigated experiments at Gatton in southeast Queensland.
Late March and mid April sowings gave better plant establishment than earlier sowing dates. Ryegrass establishment was negatively correlated with maximum and minimum daily temperature and with relative humidity.
In three of the four years, sowing in early March produced up to 2.2 t ha-1 more forage in autumn than sowing in late March and up to 3.8 t ha-1 more than sowing in mid April. Annual, broadleaf weeds contributed up to 45% of this early forage. There was a compensating loss of production in winter from early March sowings but all sowing times gave similar spring yields. Late March sowings produced the highest ryegrass, and the lowest weed, yields over the fill growing period (March to December). Sowing time had little influence on the incidence of rust and there were no cultivar/sowing date interactions.