Thursday, 8 August 2019
Growers will have breathed a big sigh of relief following the recent lifting of Maleic Hydrazide (MH) label restrictions, which prevented them from feeding MH-treated potatoes to livestock. This decision brings a significant wave of optimism to the industry, following CIPC non-renewal. MH’s non-volatile nature mean that it has fairly long-lived effects after in-field application, unlike the other volatile sprout suppressants currently available. In addition, sprouting has been shown to be significantly reduced when MH is combined with other suppressants. Its effective use will therefore go a long way in making these alternative options more affordable. The contribution of MH as part of an affordable and integrated approach to sprout suppression post-CIPC will therefore be critical going forward.
An ongoing research project at Sutton Bridge Crop Storage Research is looking to explore how MH can be used more effectively as a sprout suppressant. Part of the work has involved scanning the scientific literature and gaining a better understanding of current practices in the UK via a survey, and in Europe through a recent visit of Dutch and German stores.
Factors affecting MH efficacy as a sprout suppressant
Unlike most sprout suppressants, MH is applied in the field and is therefore directly impacted by environmental and crop or canopy factors. The latest research suggests that timing of application, as well as crop condition have a significant effect on efficacy, due to sub-optimal intake in particular. Field trials in the US indicate that early application in June has a negative effect on yield and increases misshapes. A drought stressed crop e.g. in a warm, dry season like the summer of 2018 in the UK does not react well to MH application and uptake is inevitably affected.
Industry survey captures snapshot of current practices
The UK survey reached growers, agronomists and advisors, representing 51 responses in total. Questions specifically focused on usage, timing, application and usage characteristics. The majority of users interviewed (78%) applied MH for sprout suppression, closely followed by secondary growth (72%) and volunteer control (66%). Timing and application results were highly variable, with timing of application varying between 2 to 8 weeks prior to defoliation and application volumes varying between <300 L/ha and 500 L/ha. This significant variation in usage perhaps highlights the importance of external factors e.g. weather and crop conditions in optimising MH efficacy, and the overall challenges in practical use.
A sub-set of interviewees not currently using MH for sprout suppression were asked about its potential future use. Interestingly, the majority said they ‘felt they were likely to need to use it for that purpose in the future’.
MH central to sprout suppression strategy in Europe
In the German and Dutch stores visited by the Sutton Bridge Crop Storage Research team, MH formed an integral part of the sprout control strategy, which combined MH with DMN or spearmint oil. The efficacy of combination treatments has also been observed in the ongoing Sutton Bridge trials investigating the efficacy of alternative sprout suppressants.
The review has helped inform the team at Sutton Bridge, to identify gaps in current knowledge, particularly on the topics of application timings and impact of environmental factors. Research trials this year are looking at minimum effective dose.
For information on the full range of sprout suppressants currently available, visit the AHDB Storage Hub.