An evaluation of seed-pellet insecticides in a precision drilled crop of sugar beet

The control of soil pests of sugar beet by means of seed-pellet insecticides was investigated on each of two farms in Co. Wexford from 2000 to 2002. The farms on which trials were conducted differed each season. A number of seed-pellet insecticides were compared with the standard methiocarb seed treatment, methiocarb supplemented with the in-furrow applied granule insecticide carbofuran-isofenphos and with an untreated control. Imidacloprid, Montur and thiamethoxam significantly reduced onychiurid numbers around seedlings compared with the untreated control and significantly reduced pest damage to seedlings compared with the standard methiocarb treatment. Imidacloprid gave best control of pest biting of seedlings and was as effective as the in-furrow incorporated granule insecticide in preventing pest damage and plant mortality at sites having moderate onychiurid infestations. Montur, while less effective than imidacloprid in controlling pest bites on seedling roots, gave consistently good plant establishment. Thiamethoxam was less effective than imidacloprid in some trials at reducing plant damage and mortality. The retardation of seedling growth and establishment recorded for insecticide proparnocarb combinations relative to insecticide-hymexazol combinations in some field and glasshouse trials could be overcome by replacing propamocarb with hymexazol.