The future of chemicals in arable farming has taken central focus at Potatoes in Practice – the UK’s largest field-based potato event – which takes place today.

Potatoes in Practice is organised and hosted by the James Hutton Institute at Balruddery Farm, Invergowrie, in partnership with AHDB Potatoes, SRUC and Agrii.

As the potato industry faces up to the loss of major chemicals – diquat for definite with CIPC (chlorpropham) likely to follow – this year’s Potatoes in Practice will focus on what growers will be using in the future.

The loss of diquat will be a major discussion point at the event; a number of plots will demonstrate alternative desiccation methods, and at a seminar devoted to chemical use Greg Dawson of Scottish Agronomy will discuss current trials looking at alternative haulm destruction methods for high-grade seed crops.

He said: “The loss of diquat is a real problem for the industry for all varieties, but particularly for those indeterminate varieties with vigorous canopies.

“We need new products or methods that promote rapid haulm kill to reduce the potential for the disease to develop in-store.

Currently, there are no chemical treatments which are as effective as diquat at killing off the mature leaf, potential alternatives such Gozai (Pyraflufen-ethyl) and Spotlight Plus (Carfentrazone-ethyl) are mainly used for stem destruction.

At the event, Dawson will discuss current trials looking at burndown alternatives, including those taking place on AHDB’s Strategic Farm network, and a separate site which Scottish Agronomy is overseeing focused on seed potatoes.

“We know that in future we will need a multi-pronged system for successful burndown,” he said.

“Our site is looking both at alternative chemical methods, as well as mechanical possibilities including flailing and root undercutting.

Root undercutting is interesting, but challenging. It involves literally cutting the roots below tuber level, which might prove difficult in Scotland; particularly where we have a lot of slopes and stony soils – not to mention the impact of wet weather.

Also covering desiccation will be Russell Whiteford of Belchim Crop Protection, who will run a workshop on the subject at a brand new early evening session.

Whiteford will review current practice and the likely options post-diquat focusing on flail and non-flail options and the difficulties growers may face if flail/spray is not an option.

He said: “I’ll be suggesting that a more holistic view of crop agronomy with regard to desiccation will be vital without diquat. This particularly relates to crop nutrition, field fertility, crop vigour and variety.”

Out in the field, the event also offered plenty of desiccation-related demos with many plots dedicated to how to destroy haulm without diquat, and two machinery demos showcasing kit currently available for mechanical desiccation.

David Young of the James Hutton Institute explained: “This year, both Grimme and Agricar are demonstrating their three-bed potato toppers.

Without diquat, there’s likely to be a growing demand for machinery able to flail the crop when it is still green, whether that is farmers investing in toppers, or contractors expanding their businesses.

Another challenge for growers, this time post-harvest, is the likely loss of CIPC, something that will be covered by AHDB’s Adrian Cunnington during the seminar sessions.

AHDB has been carrying out trials on potential replacements for CIPC, which have so far found that mixtures of products such as DNM and maleic hydrazide, are the most effective in suppressing sprouting in store. However, no combination is as effective as CIPC and at Potatoes in Practice Adrian is keen to focus on practical strategies that will help growers maintain quality.

He said: “Not only do we need effective replacements for CIPC, but we also need to get stores running more efficiently.

“To make sure these alternatives work, we will need much tighter control of conditions – potentially with changes to temperatures.”