The effect of insecticide seed treatments on pests of sugar beet in Europe: results of the IIRB co-operative trials with pesticides added to pelleted seed in 1991, 1992, 1993

Three series of trials to examine the effect of imidacloprid, tefluthrin and carbofuran on plant establishment and sugarbeet protection were carried out in 16 countries in 1991, 1992 and 1993 using the same batch of seed each year. Imidacloprid was tested at 3 rates (30, 60, 90 g a.i./100,000 seeds) and two pelleting types (SUET, GERMAIN'S EB) in 1991 and 1992, and at 4 rates (30, 45, 60, 90 g a.i./100,000 seeds) with SUET pellet in 1993. It was compared to carbofuran at 30 g a.i./100,000 seeds, tefluthrin at 6 and 12 g a.i./100,000seeds and to untreated seed. In some trials microgranules (carbofuran or aldicarb) were used as standard treatment. In 1991, the pellet type had no influence on plant establishment. The best establishment was obtained from tefluthrin-treated seed at 12 g a.i./100,000 seeds. Imidacloprid showed a delay of some days in plant establishment. In some bad germination conditions, carbofuran and imidacloprid at 90 g a.i./100,000 seeds showed slight phytotoxicity. Imidacloprid gave the best control of Atomaria linearis and millipedes, even when severe attacks occurred. Tefluthrin was better when applied by GERMAIN'S EB. Imidacloprid was superior to the other insecticides against Chaetocnema tibialis and Myzus persicae, and in controlling virus yellows. There were no differences between rates of imidacloprid on the protection given against pests. In 1992, the SUET pellet gave a better overall plant establishment than GERMAIN'S EB. Imidacloprid showed light phytotoxicity in several countries, but gave very good protection against Atomaria linearis and Agriotes spp. but the 30 g a.i./100,000seeds rate was a little less efficient than the other doses. Tefluthrin performed better when applied by GERMAIN'S EB, but was too low when severe attack of Onychiurus armatus and Atomaria linearis occurred. All rates of imidacloprid gave, like carbofuran, a good control of foliar attacks of Chaetocnema, Lygus and Pegomyia. Imidaclopfid gave the best protection against Myzus persicae, Aphis fabae and virus yellows. In 1993, imidacloprid gave interesting results against the Mediterranean pests, Bothynoderes sp. and Tanymecus, although 90 g a.i./100,000 seeds was phytotoxic. Root protection was also better with imidacloprid than tefluthrin 6g a-i./100,000 seeds when Onychiurus or Aloniaria were present. Carbofuran and imidacloprid (all rates) gave good control of Pegomyia, Chaetocnema and Lygus damage. The three highest rates of imidacloprid gave a better protection than aldicarb against Myzus persicae and virus yellows.