The crucial component


16 June 2023
The crucial component

CROP protection manufacturer UPL has reminded potato growers of the importance of maleic hydrazide in sprout control and has issued best practice guidance to maximise its effect this season.

Maleic hydrazide is found in UPL's potato plant growth regulator, Fazor, as well as Certis's Crown MH, and is crucial in potato sprout control programmes. 

Jonathan Kemp of Mercian Ltd, the largest supplier of potatoes to the crisping industry in the UK, believes that a grower’s potato sprout control programme should begin with an in-crop application of Fazor. He said it is 'the most important application for potato storage" and, if unused, growers can find it difficult to manage their crop storage.

To help maximise the value of maleic hydrazide this season, UPL has issued guidance to potato growers. 

“90% of growers are using maleic hydrazide,” said Geoff Hailstone, UPL’s Potato Technical Expert. “It has become essential to start a sprout control programme, and because it is applied to the crop, it is the most cost-effective method. Typically, the first application of Argos (orange oil) will not be necessary until two to three months after storage if the crop has had an application of Fazor. 

"Without this, an application of Argos might be needed within two to six weeks, or even sooner following a hot growth season. In addition, crops treated with Fazor have a lower risk of secondary growth, reduced internal sprouting in store, and it significantly reduces volunteer potatoes in the following crops.”

Like all plant growth regulators, timing the application for the correct growth stage is crucial. It is important that maleic hydrazide is properly absorbed and translocated to the growth points of the tubers. 

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Geoff advises an application when the saleable tubers are larger than 25mm, at the first signs of the lowest leaves senescing, when some flowers are still present but most have fallen, and three to five weeks before haulm destruction. 

“Getting the correct timing can be tricky, especially when growers are juggling blight spray programmes and irrigation, but growers must prioritise because they only have one opportunity to get it right. In particular, the tuber size must be correct because if Fazor is applied too early, it may prevent tuber development and cause loss of yield,” he said. 

“This is because maleic hydrazide stops cell division but not cell expansion. Once tubers have reached 25mm in size, the cell division is complete, and there is no negative effect on the yield.”

“When it comes to application, Fazor should not be tank mixed with any other products. It should not be applied less than 24 hours before irrigation or rainfall, and only in the evening if the daytime temperatures exceed 25degC. I would recommend a water volume between 350 and 550 litres per hectare to get the optimum crop coverage.

“Where ideal application conditions are not possible, there is still very valuable sprout suppression from maleic hydrazide levels of three or four parts per million, but if growers are able to follow this guidance, then they will have achieved a significant milestone in ensuring their potato crop has the best possible marketable quality.”

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