Why growers should start using sprout suppressants now

Why growers should start using sprout suppressants now

This season's potatoes will be under more pressure to sprout due to a combination of the hot summer temperatures and growers' inability to use maleic hydrazide.

Because of this, growers are urged to take action quickly and treat crops with a brand-new sprout suppressor.

As 1,4SIGHT (1,4-Dimethylnaphthalene, or DMN) was just approved by the Chemicals Regulation Division of the Health and Safety Executive, they can now use it for the first time this season.

DMN is a tested product whose commercial use started in the US in 1996. A few European nations are now using it, and people there have praised its effectiveness.

High-stress period

The product is delivered during a season with high sprouting pressure, according to specialists, and early treatment may be crucial.

There have been instances of sprouting in the field, says Adrian Cunnington of Potato Storage Insight, an independent storage specialist. The buildup of heat is the cause of this early dormancy break.

Ajay Jina, technical manager at DormFresh, the company that created DMN, adds that this summer's harsh weather also prevented many sprays of maleic hydrazide from reaching crops.

Similar to CIPC, maleic hydrazide is a growth regulator that can provide background repression of sprouting.

The optimal time to apply MH is three to five weeks before the destruction of the haulm, however at that time, the temperatures were too high. Fazor or Crown MH, for instance, ought to have been used when the temperature was below 25C.

Also, it is used when 80% of the tubers are 20 mm or larger, however many crops weren't at that size and weren't eligible.

Hence, both experts concur that early treatment will be essential when employing DMN because this storage season's sprout management may be challenging due to reduced residual control.

Mr. Jina advises gardeners to administer DMN to active potatoes as soon as they have dried and cured.

For the substance to be absorbed via the skin, they must be dry, and adequate uptake is crucial for tubers to have a high enough concentration to function properly.

He notes that delaying it would require growers to apply more and more frequently to control sprouting, particularly under high-pressure circumstances.

He suggests:

  • Earlier than usual, even on crops that have already received maleic hydrazide
  • When fresh sprouting initially appears, use the second application.

If growers apply DMN early enough, says Mr. Cunnington, it should be effective.

Use of DMN: Key issues addressed

This season, growers have a choice between four post-harvest sprout suppressants thanks to the introduction of 1,4-Dimethylnaphthalene, or DMN.

Which are:

Orange Oil, Mint Oil, and Ethylene DMN

How does DMN operate and what is it?

Growers should first take into account the fact that DMN, like the others, is not CIPC, according to independent storage expert Adrian Cunnington.

With an unconventional method of operation, CIPC was exceptional. It was used as a real fog, stopping cell division (a suspension). The potato's surface particles served as a reservoir that volatilized over time, topping off levels in any sprouts and providing the crucial "residual control."

DMN, on the other hand, is a dormancy booster. It is a substance that occurs naturally in potatoes. It was initially developed by Harry Duncan of the University of Glasgow in the 1980s.

The substance DormFresh is marketing is a synthetic copy of the original substance.

How do you obtain it?

According to Ajay Jina of DormFresh, DMN is deployed as a hot fog into retailers this year and is accessible through contractors.

According to Mr. Jina, several significant growers are expressing interest in using the product, and it might become more readily accessible in the years to come.

What dosage is usual?

Although the label only allows for a maximum of six 20ml treatments, according to Mr. Jina's experience in Europe, producers rarely need that many.

DormFresh is discovering that producers normally need 60ml/t in three to four applications, though this might vary according on the season, whether it's for fresh or processing markets, the type of store, and other factors.

The company notes that users have been able to lower rates to as little as 30ml/t for long-term storage by optimizing storage procedures and matching application doses to crop requirements (more than seven months).

Exists a residue cap?

The maximum residual limit for DMN is 15 mg/kg (15ppm). Also, because there is a 30-day harvest period, growers have less latitude when unloading stocks.

According to Mr. Jina, DormFresh is seeking to get this stopped by giving the authorities further information.

Until then, Mr. Cunnington warns that growers may have to choose one of the alternatives with a shorter harvest period if things don't go according to plan, such as delays at the factory or excessive sprouting pressure near to unloading.

Orange oil and mint oil are also appropriate for this. For instance, orange oil only lasts for 48 hours.

How does air management work?

Stores must be closed for 24 to 48 hours after fogging to allow for the uptake by the potatoes, and some usage of fans is required to provide circulation of the substance.

Mr. Jina says that because DMN is so volatile, it distributes quite well throughout the store. Yet, having appropriate ventilation in the store contributes to maximizing effectiveness.

Since air must pass through potatoes in order to apply sprout suppressants, Mr. Cunnington claims that bulk stores make the process relatively simple, but condensation issues must be avoided. Growers would need to clear loose soil during a wet season.

Box stores are trickier since their air circulation systems are typically worse. According to Mr. Cunnington, they might need to be carefully regulated to prevent issues like short circuiting and cold spots, which result in ineffective chemical distribution.

What is the price?

Mr. Cunnington estimates that the price of DMN will fall somewhere between mint and orange oil, which are priced at roughly £4.50/t and £3/t, respectively.

How did DMN do in the crop storage research trials at Sutton Bridge?

The research's project manager, Mr. Cunnington, recalled tests comparing CIPC with substitutes such as ethylene, DMN, orange oil, mint oil, and (see graphs).

In tests at Sutton Bridge, including warmer temperature processing potato depots, where sprout suppressants are most frequently employed, it generally provided the best result.

What about Northern Ireland, then?

According to Mr. Jina, DMN is only authorized for use in Great Britain, hence Northern Ireland potato farmers cannot use it. A request for an emergency authorization is being made, and it might be approved later this year.

How breeding could be beneficial in the long run

The days of preserving potatoes above 10C, according to independent potato storage expert Adrian Cunnington, are over.

According to Mr. Cunnington, CIPC was successfully utilized to keep potatoes at 11 or 12C. Yet, at these higher temperatures, sprouting pressure is at its peak, necessitating a larger reliance on chemical control.

Other processing-types that can be kept at lower temperatures, in his opinion, are needed.

"You may acquire more sugars at cooler temperatures, which results in brown crisps." Certain kinds, however, are less prone to this browning.

For instance, taurus needs to be maintained heated to get the necessary quality, whereas the crisping variety Claire may be stored cool.

"For prolonged storage, we should aim for more moderate temperatures, such sixes and sevens.

At these lower temperatures, he claims, growers would still need to apply sprout suppressants, but fewer applications would be necessary.

Breeders must therefore work to release types that are suitable for consumption and can be preserved in cooler environments.

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