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Additional flexibility to sprout suppression

Certis have announced the availability of a new formulation of GroStop, their CIPC based potato sprout suppressant.

Droplet distribution achieved using the spinning disc applicator.

Certis have announced the availability of a new formulation of GroStop, their CIPC based potato sprout suppressant.

“The new GroStop Ready formulation, containing 120g/l of chlorpropham, differs from hot fogging applications in that the product is applied as an atomised spray at store loading,” reviews Dr Tudor Dawkins, Technical Manager at Certis UK.

“Formulated as an oil in water emulsion the product is applied using a spinning disc applicator to the potatoes as they are loaded into boxes, with a drop between two conveyor belts facilitating full coverage of each tuber with CIPC,” he explains. It will be of particular use in boxed stores where sprout control can be difficult to achieve.

Good coverage of CIPC is one of the factors that will help to successfully effect good sprout suppression although it is known that some re-distribution occurs on tubers which can be a benefit if the tubers are contaminated with soil. Whilst soiled tubers are not ideal, CIPC moves under the soil cap as the soil dries.

The maximum individual application rate for potatoes is 150ml/t which applies a rate of 18g CIPC per tonne. Dr Dawkins notes that the application rate has been shown to give good suppression of sprouting in potatoes for up to six months.

“If potatoes are to be stored for longer, a low dose application of GroStop Ready can be followed up with a hot fogging treatment as required,” he says. “A repeat low dose programme has not only been shown to be effective but also helps with residue management,” he notes.

Varieties and GroStop Ready

Dr Dawkins explains that the GroStop Ready application technique is not suitable for use with all varieties. With thin skinned varieties at risk of skin burn, Certis have run a number of tests on a range of varieties. Varieties which are known to be ‘low risk’ of skin burn include King Edward, Lady Claire, Lady Rosetta, Markies, Pentland Dell and Russet Burbank. Growers are urged to take advice before considering this new formulation. Certis can be contacted for more extensive information.

With any CIPC containing products, a delay in the skin finish process can occur with application at harvest. Growers are urged to evaluate the risk of powdery scab and skin spot as two infections which – if the skin finish process is delayed – would make a fogged application the preferred option.

Dr Dawkins believes this new GroStop Ready application technique is definitely a step in the right direction, as far as CIPC usage is concerned. “We have seen very good results, to date, using less CIPC,” he says.

In trials, GroStop Ready has demonstrated strong levels of sprout control, even during last year’s challenging storage season.

Certis’ regulatory affairs officer, Dr Edward Smith, was there to witness the trials. He believes they illustrate the fit of this CIPC formulation and represent another tool available for the application of sprout suppressants in keeping with the tough regulatory requirements placed upon the active ingredient.

“GroStop Ready is a formulation of CIPC that is well placed to deliver sprout suppression results, whilst maintaining CIPC levels within the MRL of 10mg/kg,” he says.

And if situations dictate, there is the flexibility to ‘top-up’ with GroStop Fog or 100 using a follow-up, conventional fogging application. But with CIPC under continuing stewardship, it’s important that the rates applied remain within the current guideline limits of 36g CIPC/tonne for potatoes destined for the fresh market. If the total dose of CIPC from any combination of products is greater than 36 g/t then treated potatoes must only be used for commercial processing, and the total dose applied to a stored potato crop must not exceed 63.75g CIPC/t.

The application equipment

The new formulation requires dedicated application equipment. Made by Mafex, it consists of a spinning disc applicator and a peristaltic pump which can be calibrated to meter the required dose onto the potatoes. The control box can be adjusted to meter the product at the appropriate dose for the rate of flow of potatoes along the belt.