With many seed potato crops around Scotland coming up to size rapidly, potato growers are getting to grips with haulm destruction which will become part of the ‘new norm’ in the post-diquat era. So writes Dr Kyran Maloney, SRUC potato specialist, in this article published by The Scottish Farmer.
The good news is that there are still viable options to bring down even vigorous canopies, but a change of mindset is needed.
The industry standard is now to ‘flail-and-spray’. The canopy is destroyed with a pulveriser and one or more follow-up desiccant sprays are used to finish the job and to prevent regrowth.
Two products are approved for haulm destruction in potato crops – Gozai and Spotlight Plus. Both contain active ingredients from the protoporphyrinogen oxidase (PPO)-inhibitor class and as such are contact herbicides.
When using a flail, it’s important to pay attention to detail. Topping during wet and windy weather risks the spread of disease-causing organisms such as blackleg bacteria. It is also important to leave 15-20 cm of stem as a target for the follow up contact herbicide – shaving the top of the drills will make controlling regrowth difficult!
It is also worth waiting two to three days after flailing before the follow-up dessicant pass, as this gives time for trash to fall away from the remaining stem sections.
PPOs are slower acting that diquat and are at their best in combination with sunlight and warm temperatures, so if possible use them during the middle of the day. The wet conditions in autumn, 2019, also demonstrated that the use of a pulveriser isn’t always possible.
Source: Read the full article in The Scottish Farmer here
Photo: Standard fare these days on a potato farm is a haulm topper. This is a Baselier model from Standen | The Scottish Farmer