Potato Review

32 POTATO REVIEW JULY/AUGUST 2022 SPROUT SUPPRESSION Potential savings The need for further treatment on top of MH will vary greatly, depending on storage duration, variety, storage temperature and quality of store. The 2020 season was a good one for MH uptake, with growers achieving very good results in store through to unloading in spring/summer 2021. Although conditions for uptake were not as ideal in 2021, Adrian says efficacy has still been positive as the current storage period draws to a close. In well managed and efficient ambient stores, he says this has allowed some growers to avoid follow-up treatment until February. In cold stores, there has been plenty of examples of growers getting through until March or April, then using a short period of ethylene treatment to see crops through to the end of storage. He says that in situations where essential oils are being used, on average growers can save one or two applications following well-timed application of MH. “You will inevitably hit a period where tubers naturally want to grow, sprout suppression becomes more difficult and other products need to be applied frequently. “That’s why it was important to have MH and its residual activity in the mix to delay sprout growth and the need for additional treatment,” said Adrian. Integrated control Independent potato specialist Simon Alexander, who advises on potato agronomy and manages seed and processing potato stores across East Anglia, has also achieved comparable savings in his stores in 2021-22. It has complimented ethylene very well where the gas has been introduced into stores and has reduced essential oil use by between one and two applications, dependant on store and product used saving £4-£8/t. Simon adds that as it is the first season using orange oil and its application interval differs to mint oil, it’s hard to tell how cost compares. “With ethylene, it is also hard to tell if there are savings, as you must start introducing the gas into store before eye movement. “However, using MH with ethylene does give you a more predictable crop to deal with, so there is less risk of losing control and it has an important role in integrated sprout suppression programmes without CIPC,” he said. Simon has carried out tuber residue testing for maleic hydrazide over the past two seasons and found that there is some variability across samples. The benchmark figure from historic data suggests that concentrations need to be a minimum of 12mg/kg, with anything lower resulting in poorer sprout control in store. Simon’s observations from his own work back this up, with smaller tubers less likely to absorb enough active substance typically being the first to break dormancy in store. Perfect conditions He sees this as a big reason to ensure the product is applied in good time and under perfect crop and environmental conditions. “As soon as your tuber size is right, you need to look at canopy development, harvest and burn-down dates to identify your ideal window. I lean towards going early, so Ordering non-foaming Crown MH in a 600-litre IBC with Fastran 850 closed transfer system can help reduce filling time and squeeze more sprayer loads into a shift when application conditions are just right, according to independent Storage Expert Adrian Cunningham.