Executive Summary
This project had two components. The first and most significant focus was to develop for the first time reliable information on the herbicide selectivity and cultivar tolerance for a range of annual pasture legumes to commonly applied herbicides. The second component involved working with the National Annual Pasture Legume Improvement Program to assist in the selection and release of aerial seeding annual legumes that could be harvested using a conventional header.

1. Herbicide screening: Meeting seed crop purity standards is an important part of the production and certification of annual pasture legume seed. To meet these standards seed crops are often sprayed with herbicides to control various invasive weeds. A high level of selectivity is achieved where grass weeds are removed. However, where broadleaf herbicides are used the level of selectivity is often much lower than that recorded for grass selective herbicides. Despite this, broadleaf herbicides do differ in their level of selectivity and this can also vary across species and cultivars of annual legumes. To better identify herbicide selectivity and cultivar tolerance, this project evaluated a range of herbicides applied to annual pasture legume cultivars. The results from this research provide clear guidelines that can be used by seed growers to make more informed decisions on herbicide choice in annual legume seed crops. For many other farmers this information will also allow them to choose more tolerant annual legume cultivars for sowing and will ensure they avoid any unnecessary dry matter and nitrogen fixation losses.

The safest pre-emergent herbicides were Yield ® and Treflan ®. The safest post-emergent herbicides were Simazine, Dual ®, Verdict ®, Broadstrike ®, and Raptor ®. It is important also to recognise that significant cultivar by herbicides interactions occurred. For example Broadstrike caused large and significant reductions to biserrula but averaged over all cultivars it was considered one of the safer herbicides to use. The most tolerant cultivars tested were Bolta, Paradana and Frontier balansa clovers, Prima gland clover and Hykon rose clover.

2. Cultivar development: In this project cultivar development was undertaken in collaboration with the National Annual Pasture Legume Improvement Program (NAPLIP). The focus was to develop an aerial seeding cultivar that would reduce the cost of seed production and avoid the need for the environmentally degrading procedure of vacuum harvesting. This required the selection of a plant that could be harvested using a conventional header. Gland clover (Trifolium glanduliferum) cv. Prima, a plant developed by Brad Nutt (Department of Agriculture Western Australia) and evaluated in this project was selected for commercialisation. Prima can be header harvested and is resistant to red legged earth mite. Herbicide studies as part of this research project also identified it as a herbicide tolerant cultivar. Prima is now in commercial production and certified seed is produced by a consortium of seed growers. Prima was commercialised through NAPLIP with the consent of RIRDC.