Following the lifting of label restrictions on maleic hydrazide (MH), the active can be used for control of potato volunteers and sprout suppression during storage.
Mark Taylor of the Fresh Potatoes Suppliers Association (FPSA) says: “Since the announcement of the non-renewal of chlorpropham (CIPC), having a restriction on the use of maleic hydrazide-treated crops had an even greater impact for growers and packers.
“By working together, we have achieved an extremely positive outcome, for which many will breathe a sigh of relief.”
Stewardship group member and head of crop storage research at AHDB, Adrian Cunnington says: “MH is an important active for volunteer control and, particularly in the current environment, for sprout control as part of an integrated programme.
“We are pleased that the industry has been able to work with CRD, via stewardship, to reach this important and sensible decision.”
In a review of ‘Maleic hydrazide as a potato sprout suppressant’ written by Mr Cunnington, he says timing of application is important. “Applying too early reduces yield; too late reduces the efficacy of uptake and sprout control is compromised. Late July or early August application (around five weeks before defoliation) is favoured for best results.”
Mr Cunnington says reductions in the permitted treatment rates for CIPC have driven an increase in MH use in recent years. In 2016, 15 per cent - 8,000 hectares of the potato crop was treated with MH.
In a survey for the review, which yielded 51 responses, 78 per cent of users said they apply MH for sprout suppression compared with 66 per cent for volunteer control. Ninety-five per cent of respondents applied MH when the foliage was more than 75 per cent green and over half did so when the canopy was fully green.
Thirteen of 18 respondents not currently using MH for sprout control felt they were likely to need to apply it as a sprout suppressant in future. Overall, MH received a modest score of 6.1-6.5 out of 10 for volunteer control, sprout suppression, control of second growth and its consistency of response, reflecting some of the risks and challenges its use can pose, says Mr Cunnington.
“It is evident that the performance of future sprout control options in potato storage will be much less predictable than CIPC. MH, whilst inconsistent in its own level of control, does provide an element of stability to a sprout suppression strategy – especially over the loading, drying and pull-down periods, and it was therefore a ‘must-have’ component of control strategies in European processing stores visited by AHDB staff.”
Storage advice line on 0800 0282111