Neonicotinoid seed treatments for managing potato leafhopper infestations in snap bean

Thiamethoxam- and imidacloprid-treated seed were evaluated for controlling infestations of potato leafhopper, Empoasca fabae (Harris), in snap bean in Minnesota in 2001 and in New York and Illinois in 2002. Efficacy of these seed treatments was assessed by rating leafhopper damage to foliage or by monitoring densities of nymphs through the season in small field plots. Thiamethoxam provided longer and more consistent protection of the crop from leafhoppers than imidacloprid. In thiamethoxam-treated plots, there was no damage to foliage and densities of nymphs were maintained below economically damaging levels from the seedling stage through bloom. Thiamethoxam at a rate of 30 g (a.i.)/100 kg of seed controlled leafhoppers for 31 d to over 38 d. Additionally, as the rate of thiamethoxam, increased, the duration of protection also increased. In contrast, imidacloprid at a rate of 60g (a.i.)/ 100 kg of seed protected early growth stages of the crop from leafhoppers in only 1 of 4 plantings. Snap bean seed treated with thiamethoxam will provide growers with an option for controlling potato leafhoppers that is safer and more environmentally friendly than using soil-applied, systemic organophosphate insecticides such as disulfoton or phorate. Furthermore, difficulty associated with properly timing foliar sprays, inadequate coverage and reduced efficacy often encountered when treating young snap bean plants are avoided using seed treatments. (C) 2003 Elsevier Ltd. All rights reserved.