Recent trials suggest the importance of nozzle choice in achieving the most from PPO-inhibiting desiccants in potato crops.
The work, undertaken by Certis Belchim, looks at the influence of nozzle choice and whether a pre-flail treatment of Gozai (pyraflufen-ethyl) could speed up skin set and stolon detachment ahead of harvest.
The trial tested two nozzle types – a standard flat fan and a Lechler IDTA nozzle. The Lechler is an air induction twin flat fan nozzle with forward and backward facing fans. The nozzle is said to improve coverage and offer 90-95% drift reduction over a standard flat fan.
Technical account manager Jeremy Booth says two applications of Gozai plus Toil (95% methylated rapeseed adjuvant oil) were made in 300 l/ha of water at T1 on 6 September and T2 on 13 September.
“One week after the first application, the plots treated with the Lechler nozzle improved the level of leaf desiccation by 45% and Gozai’s activity on the stems by 20%. Using the backward and forward twin fan nozzle will achieve the outcome you want much quicker than the standard,” he suggests.
Pre-flail treatment
On the benefit of a pre-flail treatment, Jeremy adds it increases the speed of skin set and stolon detachment, and could be a useful application in some seasons.
With desiccation programmes about to start in earnest, he says that aside from nozzle choice, crop and environmental conditions at application have a significant influence on speed of kill.
“High UV light intensity helps improve activity of PPO-inhibitors like Gozai, so spraying at the start of a sunny day is best and if flailing, 15-20cm of stem should be left above ground to aid kill.
“Previous work has also highlighted the importance of water rate and we see that 300 l/ha balances consistent results with sprayer efficiency,” comments Jeremy.
Late blight
With reports of foliar late blight infection in crops this season, he stresses the importance of maintaining disease protection until all foliage is dead. “We support the recommendation of Gozai plus Toil with our blight fungicide Ranman Top (cyazofamid). Ranman Top offers good protection of both foliar and tuber blight, which is crucial at the backend of the season.”
