New lupin cultivars are sufficiently tolerant to selected herbicides to allow effective application of those herbicides in a variety of weed infestations.
WA Department of Agriculture scientists have come to this conclusion after a series of trials using Simazine and a suggested alternative, Metribuzin. The trials were partly funded by growers through the GRDC.
Gungurru lupins tolerated the highest rate of Metribuzin tested at all sites without any loss of grain yield, and were more tolerant than other cultivars to Simazine. Merritt showed intermediate tolerance, and Yorrel, Danja and Illyarrie were sensitive.
Generally, with exceptions noted below, the required rate of Metribuzin application was from 70-100 g/ha, depending on the target weeds.
Metribuzin gave good control of doublegees, but a mixture of Metribuzin and Simazine or Metribuzin and diflufenican was needed to give the best control of large transplanted doublegee. The only herbicide option for large wild radish (up to 1 metre in diameter and height) is 105 g/ha Metribuzin plus 50 g/ha diflufenican.
Fumitory was controlled by 50 g/ha Metribuzin but 0.5 kg/ha Simazine gave the same result.
In certain trials Simazine controlled grasses better than Metribuzin, but some grass control was a bonus in Metribuzin's control of broad-leaf weeds.
Growers are already able to adjust their herbicide rates as a result of these findings.