Nematicidal activity of fipronil against Pratylenchus zeae in sugarcane

No nematicide has been registered for controlling plant-parasitic nematodes in sugarcane in Japan. Greenhouse and field experiments were conducted to evaluate the efficacy of the phenylpyrazole insecticide fipronil (0.3–0.45 kg a.i./ha) against the root-lesion nematode, Pratylenchus zeae, which is an important plant-parasitic nematode species associated with sugarcane (Saccharum spp. hybrids) in Okinawa, Japan. Both experiments showed a reduction of P. zeae population densities in sugarcane roots to 27 to 56% of the non-treated control after 7 wk in the greenhouse experiment and 3 months in the field experiment (two trials). In contrast, P. zeae population densities in soil were not reduced by the fipronil treatment. At harvest, sugarcane yields in the field experiment were significantly increased by 6 to 8% in the fipronil treated plots compared to the non-treated control. The data showed that fipronil reduced numbers of P. zeae in sugarcane roots at the early stage of sugarcane seedling growth resulting in increased sugarcane yields. This is the first report of nematicidal activity of fipronil against P. zeae under field conditions.