Abstract

Foliar application of a benzothiadiazole (BTH), as Bion WG50 (50 mg active ingredient/mL), to glasshouse-grown Cabernet Sauvignon grapevines caused a significant reduction in egg deposition by root-knot nematodes in 10-week-old plants. No change in the number of nematodes in roots of treated grapevines was observed 3 days after inoculation, but fewer mature nematodes were recorded after a further 18 days. BTH was not toxic to the juvenile nematodes in vitro. The activity of β-1,3-glucanase increased in the leaves of BTH-treated grapevines at 7 and 28 days, and increased slightly and transiently in the roots at 5 days after foliar application. The results are interpreted as indicating the activation of systemic resistance to nematode development in the roots.