British growers warned of dual threat to potato crops: Wireworm risk rises amid wet soils

As potato planting continues apace, to make up for lost time, growers are being warned that wet soils over the winter and spring could increase the risk of wireworm damage in potato crops this season. Research over recent years has identified high soil moisture as a precursor for pest activity, with wet areas and flood plains increasing pressure levels.

Coupled with other risk factors of reduced cultivations in the autumn last year and the capability for overwinter cover crops to harbour wireworm populations, there is a double whammy of potential problems in potato crops planted this spring, warned Syngenta Technical Manager, Andy Cunningham.

“Wireworm is an increasing issue in cereal rotations, particularly where there’s grass weeds in stubble or left as cover – be that with stewardship scheme compliance or limited chance for cultivations in the autumn that disrupt the pest,” he highlighted.

“Weather conditions have severely curtailed growers’ opportunities for Integrated Pest Management (IPM) cultural controls of wireworm.”

Results of Syngenta trials in Lincolnshire last year showed Nemathorin incorporated at the wireworm rate of 15 kg/ha at the time of planting reduced the proportion of wireworm damaged tubers to just 2% of the harvest, compared to 9% in untreated areas.

Furthermore, the severity of damage was also reduced, with no tubers in the Nemathorin treated areas showing more than five holes, and significantly fewer with 1 to 5 holes. Over 2.5% of the untreated crop had an unacceptable 3 or more wireworm holes. He also reported trials had shown using Nemathorin at a higher rate of 30 kg/ha in a high-pressure field situation had halved the number of tubers seriously affected by wireworm.