Following extreme, dry conditions, potato growers are urged to risk assess and where necessary, carry out a pre-harvest residue test of tubers.
This is for where granular nematicide has been applied at planting, to assess where low soil moisture levels throughout spring and early summer have potentially caused higher than expected levels to remain in the soil profile later into the growing season.
The issue could be compounded for growers with limited or no irrigation resources, especially earlier in the growing season.
Independent agronomist, Simon Alexander, explains that growers should take a representative sample from the treated area, selecting tubers from multiple plants across the field in a ‘w’ shaped pattern. “A sample of at least 2.5kg of tubers should be submitted for testing.”
Harvest interval
The product label for fosthiazate states the product requires a minimum of 119 days (17 weeks) from planting to haulm burndown or harvest, and regardless of any residue test results, the harvest interval must be complied with.
Several independent residue testing facilities are available across the UK; any laboratory used should be ISO17025 accredited to satisfy the Red Tractor Fresh Produce scheme and other assurance schemes.
Patrick Mitton, chair of the Nematicide Stewardship Programme (NSP), endorses a proactive approach. “The NSP has a long history in promoting best practice use and handling of granular nematicides.
“The advice being offered for this extremely dry season helps to guide the end of season actions of growers in their collective support for the continued use into the future of granular nematicides, such as Nemathorin 10G.”
Find NSP best practice guidelines here: www.nspstewardship.co.uk
