Following the withdrawal of the substance from the market in 2019 and a final use up date of February 4, 2020, for stocks left in store, Leigh McClean Development Adviser at the College of Agriculture, Food and Rural Enterprise (CAFRE) advises Northern Ireland potato growers to consider alternative options for burn down this season. Una Culkin reports for Farming Life in this article.
Leigh McClean said: “A number of alternative desiccation methods exist. Some such as root cutting, haulm pulling, haulm electrocution and applying salt solution have been trialled and shown varying degrees of success at defoliating the potato crop but are either too costly, too slow or raise other issues which mean they are not currently viable methods for local growers.
“Chemical alternatives still exist in the form of a group of herbicides called PPO inhibitors of which there are two products, Spotlight Plus (Carfentrazone) and Gozai (Pyraflufen-ethyl) registered for use in potatoes.
“Mechanical flailing is one alternative commonly used in England and Scotland to replace the role of Diquat in removing foliage. Growers there have successfully been using this practice with a follow up application of a PPO inhibitor 24 to 48 hours later, once stems have started to wilt. This approach instantly stops passive bulking giving growers more control of tuber size important for higher value markets such as salads and seed.
“Flailing however poses a number of challenges. A single bed machine requires a pass over every bed. Triple bed machines reduce wheeling’s but need a larger, heavier tractor to drive them.
Leigh McClean added: “PPO inhibitors can take longer to give the same effect as diquat so plan to make the first application seven to ten days earlier than usual.
“Trials have shown both products work best in bright, sunny and warm conditions. Yes, these kind of days are at a premium but prioritise burndown sprays on bright days as close to the middle of the day when sunlight is strongest. Good application to maximise spray penetration into the canopy is key. Slow forward speeds, high water volumes, forward and backward facing nozzles applying a medium quality spray will all help maximise product efficacy.
Read the full article in Farming Life here
Photo: A demonstration of triple bed haulm flailers at Potatoes in Practice in 2019 prior to the introduction of social distancing guidance | Farming Life