Potato Review

www.potatoreview.com POTATO REVIEW MARCH/APRIL 2021 21 WEED CONTROL varietal restrictions and is proven on dealing with a broad spectrum of weeds. Regular dialogue with Russell Whiteford, representing agrochemical manufacturer Belchim Crop Protection, into maximising results from use of Praxim alongside other actives has also been extremely valuable. “On a one-spray strategy in favourable weather conditions with a low-medium weed burden I would generally advise Praxim plus metribuzin with the contact herbicide Gozai (pyra ufen-ethyl) on metribuzin tolerant varieties. On messier elds however, I would start with 1.25L/ha of Stomp Aqua (pendimethalin) applied seven to 14 days post planting when ridges have settled, then follow up with the same Praxim + metribuzin + Gozai mix three or four weeks after planting. “ ere’s no doubt that Gozai o ers consistent broad spectrum weed control. e key is application timing - making sure you target the weeds in their early growth stage when they can be more easily dealt with.” “No second chances” Frontier colleague Steven Penrice, who has been with the company for eight years, covers a large territory made up of Aberdeenshire, Fife, Angus and Perthshire. He endorses Peter’s approach and also believes diquat’s former role in early season weed control was undervalued in comparison to its high pro le use in desiccation. “Peter’s point on the new issues with volunteer cereals is certainly valid and I’d add that diquat’s ability to deal with large emerged weeds was also signi cant. Although my general preference would be a two-spray weed control strategy in higher weed burden situations, in Aberdeenshire, where the growing season is even shorter, I often have to go with a single spray strategy so there are no second chances, particularly with seed crops. “On non-metribuzin tolerant varieties my preferred option is 2.5L/ha of Praxim + 3L/ha of prosulfocarb + 0.4L/ha of Gozai, particularly in sandy soils. In higher weed burden situations I would look to add pendimethalin, like Peter, once the beds have settled, to take pressure o the Gozai enabling it to deal with emerged weeds before the potato plants start to emerge,” said Steven. Despite last year’s dry spring and initial concerns around prosulfocarb’s low water solubility, Steven was able to report a number of successful outcomes on farm. “When I partnered prosulfocarb with Praxim, a moderately water-soluble herbicide, I noted that the Praxim was able to work synergistically with the prosulfocarb increasing the e ectiveness of the overall tank-mix. is was particularly useful last year during a very dry spring with little moisture in the soil,” he said. “On contact herbicides Gozai is still the best label in my opinion, o ering a wide spectrum of control on chickweed, larger volunteer oilseed rape and even on very stubborn weeds such as black bindweed. In elds with signi cant cleaver populations, I would also advise adding clomazone to the residual tank-mix.” “Although my general preference would be a two-spray weed control strategy in higher weed burden situations, in Aberdeenshire, where the growing season is even shorter, I often have to go with a single spray strategy.”