Loss of actives remains a key concern for potato growers. However, alternatives are being investigated, delegates attending BP2019 heard.
Some growers have seen promising results from trialling Saltex – a salt brine using sodium chloride from mined sources – for potato desiccation. The product is currently used on carrots and sugar beet as a fertiliser, but potatoes do not have a nutritional requirement for it.
David Booty, technical development manager at Omex, which markets the product, said Saltex has a known herbicidal effect and is good at controlling volunteer potatoes. While the time and cost of seeking approval for sodium chloride as a herbicide is unlikely to be worthwhile, Mr Booty said the company is looking into the possibility of gaining basic substance approval for the salt - a less onerous process - which could allow it to be used as a desiccant.
Mr Booty said: “Quite a lot of growers have taken a look at it on a small area of potatoes and results have been encouraging. It looks like you can get the same rapid defoliation as with diquat.”
Graham Tomalin of VCS Agronomy said AHDB SPot Farm Network trials this season had shown PPO inhibitors such as Gozai (pyraflufen) and Spotlight (carfentrazone) had worked ‘quite well, particularly on a fine day’. “If we had had the weather we had in October in September, activity of PPO inhibitors would have been much poorer.”
Mr Tomalin suggested further research was needed on Saltex in combination with approved desiccants, and investigation of methods to improve coverage and performance of remaining actives such as nozzle choice, forward speed, adjuvants and climatic conditions.