Seventeenth Australasian Weeds Conference Summary Extensive

use of flupropanate over the last 20 years has selected for resistance in Nassella trichotoma ( serrated tussock) across Australia. To determine its genetic basis, reciprocal crosses were made between resistant and sensitive parents. In the F1 generation, both sensitive and resistant plants produced seedlings true to type when mated with the same type and 7–10 % of the opposite type when mated with the opposite type. The heritability of flu-propanate resistance from both the parents suggests a genetic origin. The 80–90 % matching of seedling type to maternal parent type strongly indicates mostly a maternal component in the inheritance, with a minor proportion through pollen