Article taken from Agronomist & Arable Farmer
Tackling new challenges following losses and restrictions on a number of key potato herbicides is part and parcel of the industry for crop adviser and potato specialist Luke Hardy.
When dealing with the serious business of growing good quality potatoes - often on rented land with weed profiles that you are not always 100% sure of - he makes sure to advise growers and other advisers to try out new chemistry when it is available.
""Following the recent loss of linuron and with serious question marks over diquat, the logical step for me was to look at Gozai (pyraflufenethyl) last season and get a proper feel for it before any more key actives leave the armoury," Mr Hardy said.
""You simply cannot afford to sit back and wait for another withdrawal to force your hand.""
Mr Hardy, who has been with Agrovista for 10 years, advises potato producers in Shropshire, Staffordshire, South Derbyshire and North Warwickshire, so sees a wide range of soil types and weed spectrums.
He added: ""Before Gozai became available I built many programmes around carfentrazone and diquat for tackling nettles and volunteer oilseed rape but I was never entirely satisfied with the combination's performance on mayweed.
""In January last year I decided to begin using Gozai as my new contact herbicide in many early season programmes and was pleased with the first season's results.""
Initially using Gozai at 0.31/ha alongside diquat at LSI/ha, Mr Hardy also trialled it alongside favoured residuals such as Soleto (metobromuron) and prosulfocarb, depending on the soil types and varieties he encountered.
""The key to maximising Gozai's effectiveness is to keep water volumes up to ensure good coverage," he commented. ""One particular customer did try to apply it in a mix at 150 litres of water per ha but you really must look at 2001/ha as a minimum. Remember, you are not spraying flat fields of wheat, you are spraying ridges, often on sloping fields!""
According to Mr Hardy's field records, Gozai proved more effective on both mayweed and groundsel than carfentrazone. Resistant poppies are a particular problem in land around Lichfield, Staffs, but he found that Gozai's faster action enabled it to deal with them.
""Gozai is certainly a viable alternative to diquat as a tank mix or as an add-in," he said. ""If you can get it on with good residuals and there's plenty of moisture, I found it clears everything in nine out of 10 cases. The key is to invest in an effective early pre-emergence programme to avoid the need for a follow-up spray. I am not a great fan of Rimsulfuron as it often knocks the crop back by up to two weeks.""
Going into the 2018 season, Mr Hardy is keen to assess how the new herbicide performs in different situations, particularly away from its usual positioning in his residual stack.
""After applying the residuals 14 days after planting as I would normally do, I intend to use Gozai on its own at the full rate of 0.41/ ha around four to five days before the crop emerges just as the ridges are cracking," he added. ""In situations when weeds are larger than four true leaves, I will add methylated seed oil to the Gozai in order to tackle any larger weeds.""