Potato Review

www.potatoreview.com POTATO REVIEW JULY/AUGUST 2020 37 STORAGE “Wherever possible we continued direct comparison with the same lots of potatoes in CIPC-treated stores to best understand the e ects and di erences and thus learn how best to use ethylene.” the natural gas for sprout control and its e ect on fry colour. Ethylene’s impact on fry colour is something that has been a concern for growers of processing varieties in the past, as treatment does have the potential to increase reducing sugars and darken fry colour during cooking. CIPC comparison Varieties Maris Piper and Royal were used in the trial and tubers from the same crop were treated with ethylene in the 1,400t box store. ey were compared with tubers treated with CIPC in a similar adjacent store. “ e results of that rst commercial experience were good and gave us the con dence to store 10,000 tonnes with ethylene in 2017, doubling that the following season, and this season we have approximately 60,000 tonnes stored with ethylene,” said Je . “ is includes all McCain medium- and long- term stores and we’ve not used any CIPC this season whatsoever.” Di erent varieties are known to react di erently to treatment with ethylene, but ongoing trials and experience has seen its use increase in almost all McCain’s main storage varieties. “Wherever possible we continued direct comparison with the same lots of potatoes in CIPC-treated stores to best understand the e ects and di erences and thus learn how best to use ethylene.” Grower experience Having gained some assurance of ethylene’s e cacy and limited impact on fry colour in the rst year, McCain began talking to some of its processing growers and recommended they consider it as an alternative to CIPC. One of the growers became involved in McCain’s commercial trials in 2017 and a second in 2018, with the rst now using ethylene in all the farm’s ware potato stores. More than a dozen more growers are now gaining experience with ethylene during the 2019-20 storage season which, importantly, is the last that CIPC can be used. McCain has opted to use an ethylene delivery system from Peterborough-based Restrain, which uses a portable ethylene generator to turn liquid ethanol product Restrain Fuel into gas. It should be noted that users require a HMRC authorisation to receive, store and use the duty- free ethanol fuel used in the Restrain generator. e system is very easy to use, with storekeepers simply placing the generator and sensor in the appropriate place, plugging it into a 240v power supply and following a ve-minute setup protocol to get it up and running. It then manages the amount of ethylene in the store’s atmosphere, slowly increasing the concentration from the start date to the required level. “ is slow ramp-up avoids the shock that ethylene may place on tubers if introduced at the full level immediately and thus mitigates any signi cant e ect on fry colour,” said Je . e Restrain generator can also be connected to the store’s ventilation control system so it switches o when louvres are open to ventilate stores with ambient air, saving a small amount of ethanol fuel. Ethylene e cacy When judging the e cacy of ethylene for sprout control since McCain has been using the Restrain system. Je said in some varieties or seasons – particularly where dormancy breaks early – short sprouts may be seen. However, these tend to be more brittle than uncontrolled sprouts or any that may occur in CIPC-treated stores. As a result, they generally fall o easily when a crop is loaded for delivery. Key points • Ethylene can provide comparable sprout control results to CIPC without residue • It has a minimal and manageable impact on fry colour • Store CO 2 level must carefully manage with ventilation when using ethylene • Maleic hydrazide provides useful support against early dormancy break “The results of the first commercial experience were good ... this season we have approximately 60,000 tonnes stored with ethylene.” McCain has seen a slight shift in fry colour when compared to equivalent CIPC stores, but any shift tends to be slow or gradual ➜