Effect of pesticides on the performance of direct-drilled lucerne

Abstract Direct drilling of forage species is a fast method of grassland renovation, but the establishment of newly seeded legumes may be adversely influenced by pests. We examined the effects of fenamiphos, heptachlor, benomyl and methiocarb on the establishment and growth of direct-drilled lucerne in two 2-year field experiments. In Experiment 1, lucerne yields were more than tripled when treated with fenamiphos, and lucerne density was also increased. Fenamiphos reduced the numbers of root lesion nematodes ( Pratylenchus penetrans ) in the soil and lucerne rootlets as well as infection of lucerne tap roots by Fusarium spp. In Experiment 2, dry-matter yields, lucerne densities and nematode numbers varied significantly between the two sites. Broadcasting fenamiphos increased total dry-matter production and reduced nematodes in the soil more than did a band application. Lucerne yield was increased by fenamiphos in the post-seeding year at one site. Compared with fenamiphos, benefits from heptachlor, benomyl and methiocarb in direct drilling of lucerne were not of practical significance.