Favourable growing conditions so far this season have boosted prospects for the 2019 potato crop, as Farmers Guardian discovers in the second of our series following agronomist John Chamberlain from Farmacy through the season.
East Anglia: John Chamberlain, Farmacy
Principal crops: processing, some salads, soft/set skin, baking potatoes
After a dry spring, last month’s rain came just in time for potato growers in south east England, boosting yield prospects, John Chamberlain says.
“Most crops established nicely with even emergence and look healthy. Those planted early did sit in the [cooler] ground a bit longer so tuber numbers are not as high as later-planted crops that initiated nicely, producing good tuber numbers and even size.”
Aphids have been a concern, with populations in early June justifying treatment of a thiacloprid-based systemic insecticide, he adds. “We’ve seen more aphid activity since then, so we’re monitoring crops closely and will treat again if necessary. Only one neonicotinoid application is allowed on ware crops, so an alternative active is needed for any follow-up.”
Although early blight pressure was very low, it has increased over recent weeks, with confirmation of the Pink EU36 strain in Essex and Suffolk. After using stronger systemic fungicides such as oxathiapiprolin (Zorvec) during the rapid canopy expansion phase, a range of chemistry will be alternated through the stable canopy period, Mr Chamberlain says.
“Products need to be tailored to conditions and variety, but if weather is hot and dry, I generally recommend cymoxanil and mancozeb-based products. If blight risk is a bit higher fluopicolide + propamocarb may be an option.”
Cyazofamid is another choice in the mid-season slot, while maleic hydrazide (Fazor) can help control production of daughter tubers in certain varieties, such as King Edwards and Markies, he notes.
“Some farmers in the Fens growing sugar beet after potatoes prefer to use Fazor to reduce the vigour of daughter tubers as it makes volunteers easier to control in the following beet crop."
Using the chemistry in-field can also help manage sprouting during storage and remove the need for in-store sprout suppression before Christmas. However, he reminds growers of new label restrictions that mean potatoes treated with maleic hydrazide-based products cannot be fed to livestock.
While most growers are likely to have sufficient stocks of diquat on-farm this season, Mr Chamberlain says it is worth considering alternative desiccation options. “Many growers in Essex flail crops, but lighter Fenland soil can’t always carry large toppers and tractors.”
Alternative desiccation options are being trialled at the Hutchinsons Fenland demo in Suffolk, where an open day will be held on 17 July, followed by a separate desiccation event later in the season.
For more information on the discoveries made by Hutchinsons agronomists David Harris (Cornwall), Andy Goulding (Cheshire) and Keith Brand (Fife and Angus) click here.