Potato growers could benefit from a new herbicide that promises to simplify pre-emergence weed control strategies this spring, according to crop protection specialist Syngenta.
The product - named Defy - is safe on all varieties, growing on all soil types, with a flexible application window, according to Jason Tatnell, Syngenta herbicide technical manager.
Treatment also controls key broad-leaved weeds and grass weeds in potatoes.
Tatnell said: “One of the key benefits of Defy is its simplicity at a busy time of year, for use on all varieties, all soil types and for all end-customer protocols. It’s very easy to use for the operator, with straightforward recommendations and excellent crop safety.”
More than 50 farmers undertook field-scale trials last year, which confirmed results of 30 replicated field trials, crop safety trials and variety screens in the UK.
Defy has been used commercially by potato growers across continental Europe for over 10 years.
The active ingredient, Prosulfocarb, is a fast-acting thiocarbamate selective herbicide but, unlike any other thiocarbamates, Defy does not need to be incorporated.
Rapid uptake through the roots and shoots ensures emerging weed seedlings quickly wither and die.
Tatnell advises a straight Defy application at 4 l/ha to control the core spectrum of key potato weeds, including Cleavers, Chickweed, Speedwells and Black Nightshade. The long-lasting residual activity, which provides control through to complete canopy coverage, will shade out further weed germination.
Tatnell says that, in cases where annual weeds have already emerged at the time of Defy application, the addition of the contact herbicide, PDQ, at up to 3 l/ha, depending on the number and size of the weeds, is recommended.
He said: “Conventional application timing for Defy is right up until crop emergence, although in field use and trials it has proven to be incredibly gentle on potatoes and causes no additional check to the PDQ effects, even up to 10 per cent crop emergence.
“Where growers also have infestations of polygnums, Fat hen, Mayweed or Poppy, they should include a partner such as linuron at 1 l/ha with Defy, plus PDQ if weeds are emerged. Metribuzin is also a potential partner on silts, heavy or high organic matter soils.
“But if growers do tank-mix with other residual herbicides, they must be aware of the varietal restrictions, timing limitations and the risk of crop damage these herbicides pose,” he warned.
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