Potato Review

34 POTATO REVIEW MAY/JUNE 2020 MH: FOLIAR APPLICATION T he potato industry will soon be embarking on its rst storage season without CIPC, which has been the go-to means of sprout suppression in store for decades. One of CIPC’s advantages was its low volatility. Once applied as a hot fog, it settled on tubers and persisted for a considerable time before reapplication was required. is was the case even where stores were regularly ventilated with ambient air, either for cooling or ushing out CO2. Now it is no longer available, there are just two approved options for use in the UK: Spearmint oil product Biox-M and ethylene gas. ere is also hope that DormFresh’s dimethylnaphalene (DMN) product 1,4Sight will be authorised in time for the 2020 storage season. How to get the best from MH With chlorpropham (CIPC) no longer available for use in potato stores, foliar-applied maleic hydrazide can provide early insurance against sprouting. We received some expert advice on how to maximise its e cacy. AHDB’s Sutton Bridge Crop Storage Research sprout suppression expert Adrian Briddon says that while these substances undoubtably have a role to play in sprout control, they are all eminently volatile. “ at means whenever we ventilate with ambient air, we are extracting the chemical or storage treatment from the store and hastening the need for reapplication,” he said. “ is will have implications for storage costs and untended, could have implications for sprout control e cacy, too.” Key role Work carried out at Sutton Bridge suggests that MH has a key role to play in dealing with the potential issues of compromised e cacy and increased cost of these volatile compounds in the early stages of storage. But growers must get the application of MH just right if they are to reap the full range of bene ts it o ers, including more cost-e ective sprout suppression in store. e foliar applied plant growth regulator – which is applied to a growing crop ahead of desiccation – is absorbed by the crop canopy and moves into the tubers. Adrian has been conducting trials for the past two years looking at MH use followed by a range of in-store treatments – Biox-M, ethylene, DMN and CIPC as the benchmark – on ve varieties. “We’ve seen that maleic hydrazide is a reasonable sprout suppressant in its own right and it can certainly give sprout control for a matter of months, but more importantly than that, it delays or reduces the need for other treatments,” said Adrian. A dose of MH costs less than £2/t which is just 80 pence more than CIPC (see sprout control product costs). Any reduction in the use of the more costly alternatives will help to keep the cost of storage under control. A foliar treatment of maleic hydrazide can delay the need for more volatile and costly sprout suppressants in the early stages after store loading. Photo: Gary Naylor